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bandicam 2020-02-11 09-45-16-567NASA-1

 

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RELATED POSTS ON ARCTIC SEA ICE: 

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THIS POST IS A CRITICAL REVIEW OF A DOCUMENT POSTED ONLINE BY NASA [LINK] CLAIMING THAT: 

(1) HUMANS CAUSE AGW CLIMATE CHANGE, (2) AGW CLIMATE CHANGE CAUSES ARCTIC SEA ICE TO MELT, (3) MELTING ARCTIC SEA ICE CAUSES THE BEAUFORT GYRE TO BECOME FASTER AND MORE TURBULENT, (4) THIS CAUSES THE BEAUFORT GYRE TO TRANSFER COLD FRESHWATER FROM ARCTIC SEA ICE MELT INTO THE ATLANTIC, (5) THIS IS HOW AGW CREATES A GREAT SALINITY ANOMALY, AND (6) THE AGW GREAT SALINITY ANOMALY SLOWS DOWN THE ATLANTIC MERIODONAL OVERTURNING CIRCULATION: {NOTE: THE BEAUFORT GYRE IS AN OCEAN AND ICE CIRCULATION PATTERN OBSERVED IN THE BEAUFORT SEA NORTH OF ALASKA [LINK] }

 

 

THE NASA STATEMENT 

  1. The 2011 NASA ICESCAPE mission was a study of “Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment”. It was a shipborne investigation to study how changing conditions in the Arctic affect the ocean’s chemistry and ecosystems. The bulk of the research took place in the Beaufort and Chukchi seas in summer 2010 and 2011. 
  2. A major ocean current in the Arctic (a reference to the Beaufort Gyre) is faster and more turbulent as a result of rapid sea ice melt, a new study from NASA shows. The current is part of a delicate Arctic environment that is now flooded with fresh water, an effect of human-caused climate change.
  3. Using 12 years of satellite data, scientists have measured how this circular current, called the Beaufort Gyre, has precariously balanced an influx of unprecedented amounts of cold, fresh water – a change that could alter the currents in the Atlantic Ocean and cool the climate of Western Europe. 
  4. The Beaufort Gyre keeps the polar environment in equilibrium by storing fresh water near the surface of the ocean. Wind blows the gyre in a clockwise direction around the western Arctic Ocean, north of Canada and Alaska, where it naturally collects fresh water from glacial melt, river runoff and precipitation. This fresh water is important in the Arctic in part because it floats above the warmer, salty water and helps to protect the sea ice from melting, which in turn helps regulate Earth’s climate. The gyre then slowly releases this fresh water into the Atlantic Ocean over a period of decades, allowing the Atlantic Ocean currents to carry it away in small amounts. 
  5. But the since the 1990s, the gyre has accumulated a large amount of fresh water — 1,920 cubic miles (8,000 cubic kilometers) — or almost twice the volume of Lake Michigan. The new study, published in Nature Communications, found that the cause of this gain in freshwater concentration is the loss of sea ice in summer and autumn. This decades-long decline of the Arctic’s summertime sea ice cover has left the Beaufort Gyre more exposed to the wind, which spins the gyre faster and traps the fresh water in its current.
  6. Persistent westerly winds have also dragged the current in one direction for over 20 years, increasing the speed and size of the clockwise current and preventing the fresh water from leaving the Arctic Ocean. This decades-long western wind is unusual for the region, where previously, the winds changed direction every five to seven years.
  7. Scientists have been keeping an eye on the Beaufort Gyre in case the wind changes direction again. If the direction were to change, the wind would reverse the current, pulling it counterclockwise and releasing the water it has accumulated all at once.
  8. If the Beaufort Gyre were to release the excess fresh water into the Atlantic Ocean, it could potentially slow down its circulation. And that would have hemisphere-wide implications for the climate, especially in Western Europe.
  9. Fresh water released from the Arctic Ocean to the North Atlantic can change the density of surface waters. Normally, water from the Arctic loses heat and moisture to the atmosphere and sinks to the bottom of the ocean, where it drives water from the North Atlantic Ocean down to the tropics like a conveyor belt.
  10. This important current is called the Atlantic Meridional Overturning Circulation and helps regulate the planet’s climate by carrying heat from the tropically-warmed water to northern latitudes like Europe and North America. If slowed enough, it could negatively impact marine life and the communities that depend it. We don’t expect a shutting down of the Gulf Stream, but we do expect impacts. That’s why we’re monitoring the Beaufort Gyre so closely.
  11. The study also found that, although the Beaufort Gyre is out of balance because of the added energy from the wind, the current expels that excess energy by forming small, circular eddies of water. While the increased turbulence has helped keep the system balanced, it has the potential to lead to further ice melt because it mixes layers of cold, fresh water with relatively warm, salt water below. The melting ice could, in turn, lead to changes in how nutrients and organic material in the ocean are mixed, significantly affecting the food chain and wildlife in the Arctic.
  12. The results reveal a delicate balance between wind and ocean as the sea ice pack recedes under climate change. What this study is showing is that the loss of sea ice has really important impacts on our climate system that we’re only just discovering. 

RESPONSE TO THE NASA STATEMENT

  1. The essential AGW/human cause case is that a causal link exists from AGW climate change to the great salinity anomaly of the 1990s. The causation sequence claimed  is as follows:  (1) AGW climate change caused Arctic sea ice to melt in summer and autumn. (2) The decline in Arctic sea ice cover rendered the Beaufort Gyre unstable and more susceptible to wind.
  2. The wind was then able to spin the Gyre around faster and faster creating turbulence and trapping more and more fresh water that had been made more abundant from the AGW driven sea ice melt.
  3. Unusually and unnaturally persistent westerly winds increased the speed and size of the Beaufort Gyre and also kept it moving in directions that would prevent all that fresh water from leaving the Arctic. The unusual persistence of the westerly winds for a decade may also be a creation of AGW climate change. (See also the assessment of the great salinity anomaly of the 1990s by Belkin (2004) in the “Great Salinity Anomalies” bibliography below.)
  4. Some conditional statements follow. IF the wind direction changes, the wind COULD reverse the Gyre’s flow to counterclockwise and that COULD release all that fresh water it had trapped and IF the fresh water were to be released into the Atlantic Ocean it COULD slow down the Atlantic Meridional Overturning Circulation and that COULD render the AMOC dysfunctional in the sense that it would be unable to regulate the planet’s climate by carrying heat from the Tropics to the Northern Latitudes. And that would surely create some CLIMATE IMPACTS. We don’t know what those impacts will be yet but it’s pretty  certain that there will be impacts.
  5. Postscript on the AMOC: As a footnote consider also the claim by Carl Wunsch that complex ocean circulation systems have been simplified to the point where the resulting analysis delivers more misinformation than information [LINK]
  6. Postscript on the “Great Salinity Anomalies” of the past:  A bibliography of salinity anomalies is provided below. An interesting note is the observation by many authors that Arctic salinity anomalies are controlled more by fresh water discharge than by ice melt.

 

 

AGW CLIMATE CHANGE & ARCTIC SEA ICE MELT IN SUMMER AND AUTUMN

  1. It is claimed in the NASA statement presented above that the salinity anomaly is a creation of AGW climate change because the process begins with sea ice melt in summer and autumn and because these melt events that create the fresh water causing the salinity anomaly are the creation of AGW climate change.
  2. That at a time of global warming subsequent years will be warmer than prior years and that warmer air temperatures would cause more sea ice melt appears to be logical. For example, this causation is seen in the seasonal cycle. A strong relationship between surface air temperature and sea ice volume in the seasonal cycle causes Arctic air temperature cycles of 40C or so from winter to summer to create the significant sea ice melt cycles in sea ice volume seen in the data.
  3. However, there is a significant difference between the seasonal cycle and long term AGW warming in terms of the range of temperatures seen in these two phenomena. The seasonal cycle range of approximately 40C from winter to summer is significantly larger than the range of deseasonalized temperatures ascribed to global warming.  For example, in the 41-year period 1979-2019, a period during which significant sea ice loss due to AGW climate change was claimed by climate science, the temperature range is closer to 4C. Therefore, seasonal cycle sea ice dynamics do not serve as a model for understanding the effect of global warming on sea ice volume. These are entirely different phenomena. A graphical display of the difference between the seasonal cycle and year to year changes in temperature  is provided below in Figure 3.
  4. Here, we use detrended correlation analysis to assess whether changes in year to year sea ice volume are related to the observed temperature rise over the Arctic that has been ascribed to AGW climate change. The results of this analysis is summarized in the correlation table presented below in Figure 6 below. If year to year temperature increases cause decreasing sea ice volume, we would expect to find a negative correlation between these two variables in the calendar months where AGW driven sea ice melt is claimed. And in fact, the second row of the correlation table labeled “CORR” does show strong statistically significant negative correlations for all calendar months.
  5. However, as described in related posts on this site, [LINK] , correlation between two time series derives not only from the responsiveness of one to the other but also from shared trends. For example if both time series are rising the shared trend will impose a positive correlation even when there is no responsiveness at the time scale of the proposed causation hypothesis. Therefore to test for responsiveness at a given time scale, the two time series must be detrended so that the trend effect is removed.
  6. Detrended correlations in the correlation table in Figure 6 are listed in the row labeled DETCOR. There we find that even at the high value of α=0.05, no detrended correlation at an annual time scale is found in the summer and fall months when AGW climate change is hypothesized to be melting sea ice and thereby creating a great salinity anomaly. The results summarized in the correlation table do not provide evidence that AGW climate change causes sea ice melt in summer and autumn. A GIF video image is provided in Figure 5 so that these correlations can be visualized.
  7. A further argument against the proposition that sea ice melt had caused a great salinity anomaly is found in many of the papers listed in the bibliography below where precipitation and fresh water runoff from rivers are proposed as the primary fresh water sources in such anomalies in the Arctic. We also find in these papers that “Great Salinity Anomalies” are not unique to AGW driven changes to the ocean described by NASA but that The Great Salinity Anomaly of the 1990s mentioned in the NASA article was just the latest such event that followed in the sequence that is traced to the Great Salinity Anomaly of the 1960s, The Great Salinity Anomaly of the 1970s,  and The Great Salinity Anomaly of the 1980s – non of which had an AGW climate change interpretation. The novelty of the current salinity anomaly as a peculiar climate change impact is less credible in this context.
  8. In summary, we find no evidence to support the claim that AGW climate change had caused a great salinity anomaly in the Arctic as described in the NASA article cited above.

 

Related post on the Ice Free Arctic Obsession of Climate Science [LINK]

 

 

FIGURE 1: Arctic Temperature Anomalies & Sea Ice Volume 1979-2019

 

FIGURE 2: The Seasonal Cycle in Arctic Sea Ice Volume 1979-2019

 

FIGURE 3: THE SEASONAL CYCLE AND LONG TERM MELT COMPARED

COMPARE-LOSSES

FIGURE 4: THE SEASONAL CYCLE IN TEMPERATURE AND ICE MELT: 1979-2019

 

FIGURE 5: VISUAL CORRELATION BETWEEN TEMPERATURE AND SEA ICE VOLUME

 

FIGURE 6: DETRENDED CORRELATION ANALYSIS: CORRELATION TABLE

CORRTABLE

 

 

 

 

 

 

 

 

 

BIBLIOGRAPHY

THE GREAT SALINITY ANOMALIES OF THE 1960S, 1970S, 1980S, & 1990S

  1. Dickson, Robert R., et al. “The “great salinity anomaly” in the northern North Atlantic 1968–1982.” Progress in Oceanography 20.2 (1988): 103-151The widespread freshening of the upper 500–800m layer of the northern North Atlantic, which this paper describes, represents one of the most persistent and extreme variations in global ocean climate yet observed in this century. Though a range of explanations have been advanced to explain this event, including in situ changes in the surface moisture flux, this paper describes the Great Salinity Anomaly as largely an advective event, traceable around the Atlantic subpolar gyre for over 14 years from its origins north of Iceland in the mid-to-late 1960s until its return to the Greenland Sea in 1981–1982. The overall propagation speed around this subpolar gyre is estimated at about 3cm s−1. Of the total salt deficit associated with the anomaly as it passed south along the Labrador Coast in 1971–1973 (about 72 × 109 tonnes), a deficit equivalent to about two thirds of this figure (47 × 109 tonnes) ultimately passed through the Faroe-Shetland Channel to the Barents Sea, Arctic Ocean and Greenland Sea during the mid-1970s.
  2. Häkkinen, Sirpa. “An Arctic source for the Great Salinity Anomaly: A simulation of the Arctic ice‐ocean system for 1955–1975.” Journal of Geophysical Research: Oceans 98.C9 (1993): 16397-16410.  A fully prognostic Arctic ice‐ocean model is used to study the interannual variability of the sea ice during the period 1955–1975 and to explain the large variability of the ice extent in the Greenland and Iceland seas during the late 1960’s. In particular, the model is used to test the conjecture of Aagaard and Carmack (1989) that the Great Salinity Anomaly (GSA) was a consequence of the anomalously large ice export in 1968. The objective here is to explore the high‐latitude ice‐ocean circulation changes due to wind field changes. In the simulations the ice extent in the Greenland Sea increased during the 1960’s, reaching a maximum in 1968, as observed, and maxima in ice extent were always preceded by large pulses of ice export through the Fram Strait. The ice export event of 1968 was the largest in the simulation, being about twice as large as the average and corresponding to 1600 km3 of excess fresh water. The simulated upper water column in the Greenland Sea has a salinity minimum in the fall of 1968, followed by very low winter salinities. The simulations suggest that, besides the above average ice export to the Greenland Sea, there was also fresh water export to support the larger than average ice cover. Three low‐salinity anomalies, which are created by the variability in ice production/melt, exited through the Fram Strait in 1963–1965, 1966, and 1967–1969, the later two events being associated with a net freshwater export of about 900 km3.The total simulated freshwater input of 2500 km3 to the Greenland Sea compares well with the estimated total freshwater excess of the GSA of about 2200 km3 as it passed through the Labrador Sea (Dickson et al., 1988). Considering the uncertainties in the model, it is possible that the ice export could account for even larger portion of the freshwater excess. However, the main conclusion is that these model results show the origin of the GSA to be in the Arctic, as suggested by Aagaard and Carmack (1989) and support the view that the Arctic may play an active role in climate change.
  3. Häkkinen, Sirpa. “A simulation of thermohaline effects of a great salinity anomaly.” Journal of Climate 12.6 (1999): 1781-1795.  Model simulations of an idealistic “Great Salinity Anomaly” (GSA) demonstrate that variability in the sea ice export from the Arctic when concentrated to short pulses can have a large influence on the meridional heat transport and can lead to an altered overturning state. One single freshwater disturbance resulting from excess ice export, as in 1968, can disrupt the deep mixing process. The critical condition for a large oceanic response is defined by the intensity, duration, and timing of the ice pulse, in particular, as it exits through the Denmark Strait. A recovery from this event takes several years for advection and diffusion to remove the salinity anomaly. Concurrently, the influence of the GSA propagates to the subtropics via the boundary currents and baroclinic adjustment. As a result of this adjustment, there are large (up to 20%) changes in the strength of the overturning cell and in the meridional heat transport in the subtropics and subpolar areas. Simulations show a temperature–salinity shift toward colder and fresher subpolar deep waters after the GSA, which is also found in hydrographic data.
  4. Belkin, Igor M. “Propagation of the “Great Salinity Anomaly” of the 1990s around the northern North Atlantic.” Geophysical Research Letters 31.8 (2004).   Time series of Temperature and Salinity extending through 2001 are used to describe propagation of the “Great Salinity Anomaly” of the 1990s (GSA’90s). Comparison of the distance‐time relations for the GSA’70s, ’80s, and ’90s reveals a substantial intensification of the large‐scale circulation in the northern North Atlantic, especially in the Subarctic Gyre between Newfoundland and the Faroes. The advection rate of the GSA’70s, ’80s, and ’90s between Newfoundland and the Faroe‐Shetland Channel is conservatively estimated to have been 3.5, 10, and 10 cm/s, respectively. The circulation intensification apparently occurred within a decade between the GSA’70s and ’80s. During the next decade the advection rate increased from 10 to 13 cm/s between Newfoundland and Iceland Basin. The GSA’90s was advected towards the Faroe‐Shetland Channel by the northern (Iceland Basin’s) branch of the North Atlantic Current, whereas the contribution of the southern branch via the Rockall Trough was minimal.

 

 

 

 

 

 

BIBLIOGRAPHY: ARCTIC SALINITY ANOMALIES

  1. Macdonald, R. W., et al. “Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre.” Geophysical Research Letters 26.15 (1999): 2223-2226.  During the SHEBA, thin ice and freshening of the Arctic Ocean surface in the Beaufort Sea led to speculation that perennial sea ice was disappearing [McPhee et al., 1998]. Since 1987, we have collected salinity, δ18O and Ba profiles near the initial SHEBA site and, in 1997, we ran a section out to SHEBA. Resolving fresh water into runoff and ice melt, we found a large background of Mackenzie River water with exceptional amounts in 1997 explaining much of the freshening at SHEBA. Ice melt went through a dramatic 4–6 m jump in the early 1990s coinciding with the atmospheric pressure field and sea‐ice circulation becoming more cyclonic. The increase in sea‐ice melt appears to be a thermal and mechanical response to a circulation regime shift. Should atmospheric circulation revert to the more anticyclonic mode, ice conditions can also be expected to revert although not necessarily to previous conditions. Note: SHEBA refers to a sea surface salinity anomaly study 1987-2004 possibly motivated by “The Great Salinity Anomaly of the 1970s” when reductions in salinity of 0.1 to 0.5 psu was observed along with water temperature anomalies of -1C to -2C. SHEBA is an acronym for “Heat Budget of the Arctic Ocean”, More information on the SHEBA study may be found here:  [LINK]. PSU , or “Practical Salinity Unit, is a measure of sea water salinity based on its conductivity. 
  2. Steele, M., et al. “Adrift in the Beaufort Gyre: A model intercomparison.” Geophysical Research Letters 28.15 (2001): 2935-2938.  Output from six regional sea ice‐ocean climate model simulations of the arctic seas is compared to investigate the models’ ability to accurately reproduce the observed late winter mean sea surface salinity. The results indicate general agreement within the Nordic seas, strong differences on the arctic continental shelves, and the presence of a climate drift that leads to a high salinity bias in most models within the Beaufort Gyre. The latter is highly sensitive to the wind forcing and to the simulation of freshwater sources on the shelves and elsewhere.
  3. Proshutinsky, Andrey, R. H. Bourke, and F. A. McLaughlin. “The role of the Beaufort Gyre in Arctic climate variability: Seasonal to decadal climate scales.” Geophysical Research Letters 29.23 (2002): 15-1[FULL TEXT]. This paper presents a new hypothesis along with supporting evidence that the Beaufort Gyre (BG) plays a significant role in regulating the arctic climate variability. We propose and demonstrate that the BG accumulates a significant amount of fresh water (FW) during one climate regime (anticyclonic) and releases this water to the North Atlantic (NA) during another climate regime (cyclonic). This hypothesis can explain the origin of the salinity anomaly (SA) periodically found in the NA as well as its role in the decadal variability in the Arctic region.
  4. Carmack, Eddy, et al. “Freshwater storage in the Northern Ocean and the special role of the Beaufort Gyre.” Arctic–subArctic ocean fluxes. Springer, Dordrecht, 2008. 145-169.  As part of the global hydrological cycle, freshwater in the form of water vapour moves from warm regions of evaporation to cold regions of precipitation and freshwater in the form of sea ice and dilute seawater inexorably moves from cold regions of freezing and net precipitation to warm regions of melting and net evaporation. The global plumbing that supports the ocean’s freshwater loop is complicated, and involves land–sea exchanges, geographical and dynamical constraints on flow pathways as well as forcing variability over time (cf. Lagerloef and Schmitt 2006). The Arctic Ocean is a central player in the global hydrological cycle in that it receives, transforms, stores, and exports freshwater, and each of these processes and their rates both affect and are affected by climate variability. And within the Arctic Ocean, the Canada Basin (see Fig. 7.1) is of special interest for three reasons: (1) it processes freshwater from the Pacific, from North American and Eurasian rivers and from ice distillation; (2) it is the largest freshwater storage reservoir in the northern oceans; and (3) it has exhibited changes in halocline structure and freshwater storage in recent years.

    In this chapter we examine the distribution of freshwater anomalies (relative to a defined reference salinity) in northern oceans by reviewing criteria that have been used to construct freshwater budgets and then by comparing freshwater disposition in the subarctic Pacific, subarctic Atlantic and Arctic oceans. This comparison provides a useful basis for the interpretation of Arctic Ocean flux measurements and affirms that the Canada Basin is a significant freshwater reservoir (Section 7.2). We next examine various hydrographic data sources within the Canada Basin (a geographical feature) to define the role of the Beaufort Gyre (a wind-forced dynamical feature) in freshwater storage and release (Section 7.3). Due to this latter feature, the upper layer circulation in the Beaufort Gyre is anticyclonic whereas circulation elsewhere in the Arctic Ocean is cyclonic. Then we examine the Canada Basin’s role as a reservoir with respect to sources of its freshwater components (e.g. meteoritic (runoff and precipitation), sea-ice melt and Pacific throughflow), and also to its water mass structure, within which freshwater components are stored (Section 7.4). This distinction among source components and among water mass affiliations is a prerequisite to interpreting downstream freshwater fluxes and to predicting the response of the Arctic system to climate variability. Finally, we combine geochemical data and recent freshwater budget estimates to calculate the relative contributions of freshwater components from the Canada Basin to other Arctic basins

  5. McPhee, M. G., et al. “Rapid change in freshwater content of the Arctic Ocean.” Geophysical Research Letters 36.10 (2009)[FULL TEXT] The dramatic reduction in minimum Arctic sea ice extent in recent years has been accompanied by surprising changes in the thermohaline structure of the Arctic Ocean, with potentially important impact on convection in the North Atlantic and the meridional overturning circulation of the world ocean. Extensive aerial hydrographic surveys carried out in March–April, 2008, indicate major shifts in the amount and distribution of fresh‐water content (FWC) when compared with winter climatological values, including substantial freshening on the Pacific side of the Lomonosov Ridge. Measurements in the Canada and Makarov Basins suggest that total FWC there has increased by as much as 8,500 cubic kilometers in the area surveyed, effecting significant changes in the sea‐surface dynamic topography, with an increase of about 75% in steric level difference from the Canada to Eurasian Basins, and a major shift in both surface geostrophic currents and freshwater transport in the Beaufort Gyre. Fresh water exiting the Arctic in both the upper ocean and the sea ice cover plays a major role in controlling convection in the North Atlantic, and consequently the global thermohaline circulation [Aagaard and Carmack, 1989Walsh and Chapman, 1990Serreze et al., 2006Peterson et al., 2006]. Changes in the distribution and discharge of Arctic fresh water may thus figure prominently in the response of the world ocean to climate change: e.g., Aagaard and Carmack [1989] pointed out that a 25% increase in the freshwater discharge through Fram Strait maintained for two years (equivalent to freshwater excess of about 2,000 km3) would account for the salinity deficit observed in the North Atlantic during the “Great Salinity Anomaly” (GSA) of the 1970s, considered by Dickson et al. [1988] to be one of the major ocean climate events observed in the 20th century. The single largest feature in freshwater storage in the Arctic is the Beaufort Gyre (BG), an extensive anticyclonic ocean circulation in the Canada Basin north of Alaska [Carmack et al., 2008]. Here we report evidence from an International Polar Year (IPY) airborne hydrographic survey executed in March–April, 2008, of both significant redistribution and net increase in volume of Arctic FWC compared with climatological values. The freshening is concentrated mainly in the BG, and appears to have accelerated in concert with recent dramatic reduction in minimum sea ice extent [Maslanik et al., 2007]. Associated changes in sea‐surface dynamic topography have modified Arctic ocean circulation, with a large increase in northward transport of freshened water in the Canada Basin, toward the Fram Strait and Canadian Archipelago passages to the North Atlantic.
  6. Proshutinsky, Andrey, et al. “Beaufort Gyre freshwater reservoir: State and variability from observations.” Journal of Geophysical Research: Oceans 114.C1 (2009)[FULL TEXT]  We investigate basin‐scale mechanisms regulating anomalies in freshwater content (FWC) in the Beaufort Gyre (BG) of the Arctic Ocean using historical observations and data collected in 2003–2007. Specifically, the mean annual cycle and interannual and decadal FWC variability are explored. The major cause of the large FWC in the BG is the process of Ekman pumping (EP) due to the Arctic High anticyclonic circulation centered in the BG. The mean seasonal cycle of liquid FWC is a result of interplay between the mechanical (EP) and thermal (ice transformations) factors and has two peaks. One peak occurs around June–July when the sea ice thickness reaches its minimum (maximum ice melt). The second maximum is observed in November–January when wind curl is strongest (maximum EP) and the salt input from the growing ice has not yet reached its maximum. Interannual changes in FWC during 2003–2007 are characterized by a strong positive trend in the region varying by location with a maximum of approximately 170 cm a−1 in the center of EP influenced region. Decadal FWC variability in the period 1950–2000 is dominated by a significant change in the 1990s forced by an atmospheric circulation regime change. The center of maximum FWC shifted to the southeast and appeared to contract in area relative to the pre‐1990s climatology. In spite of the areal reduction, the spatially integrated FWC increased by over 1000 km3 relative to climatology.
  7. Giles, Katharine A., et al. “Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre.” Nature Geoscience 5.3 (2012): 194-197.  The Arctic Ocean’s freshwater budget comprises contributions from river runoff, precipitation, evaporation, sea-ice and exchanges with the North Pacific and Atlantic1. More than 70,000 km3 of freshwater2 are stored in the upper layer of the Arctic Ocean, leading to low salinities in upper-layer Arctic sea water, separated by a strong halocline from warm, saline water beneath. Spatially and temporally limited observations show that the Arctic Ocean’s freshwater content has increased over the past few decades, predominantly in the west3,4,5. Models suggest that wind-driven convergence drives freshwater accumulation6. Here we use continuous satellite measurements between 1995 and 2010 to show that the dome in sea surface height associated with the western Arctic Beaufort Gyre has been steepening, indicating spin-up of the gyre. We find that the trend in wind field curl—a measure of spatial gradients in the wind that lead to water convergence or divergence—exhibits a corresponding spatial pattern, suggesting that wind-driven convergence controls freshwater variability. We estimate an increase in freshwater storage of 8,000±2,000 km3 in the western Arctic Ocean, in line with hydrographic observations4,5, and conclude that a reversal in the wind field could lead to a spin-down of the Beaufort Gyre, and release of this freshwater to the Arctic Ocean.
  8. Morison, James, et al. “Changing arctic ocean freshwater pathways.” Nature 481.7379 (2012): 66-70Freshening in the Canada basin of the Arctic Ocean began in the 1990s1,2 and continued3 to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly4,5of the 1970s, raising the spectre of slowing global ocean circulation6. Freshening has been attributed to increased sea ice melting1 and contributions from runoff7, but a leading explanation has been a strengthening of the Beaufort High—a characteristic peak in sea level atmospheric pressure2,8—which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors2 must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation9 index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation. (Note: This is a bold and anti “consensus” view. The consensus view is that AGW melts sea ice and sea ice melt causes salinity anomalies)
  9. Krishfield, Richard A., et al. “Deterioration of perennial sea ice in the Beaufort Gyre from 2003 to 2012 and its impact on the oceanic freshwater cycle.” Journal of Geophysical Research: Oceans 119.2 (2014): 1271-1305[FULL TEXT]   Time series of ice draft from 2003 to 2012 from moored sonar data are used to investigate variability and describe the reduction of the perennial sea ice cover in the Beaufort Gyre (BG), culminating in the extreme minimum in 2012. Negative trends in median ice drafts and most ice fractions are observed, while open water and thinnest ice fractions (<0.3 m) have increased, attesting to the ablation or removal of the older sea ice from the BG over the 9 year period. Monthly anomalies indicate a shift occurred toward thinner ice after 2007, in which the thicker ice evident at the northern stations was reduced. Differences in the ice characteristics between all of the stations also diminished, so that the ice cover throughout the region became statistically homogenous. The moored data are used in a relationship with satellite radiometer data to estimate ice volume changes throughout the BG. Summer solid fresh water content decreased drastically in consecutive years from 730 km3 in 2006 to 570 km3 in 2007, and to 240 km3 in 2008. After a short rebound, solid fresh water fell below 220 km3 in 2012. Meanwhile, hydrographic data indicate that liquid fresh water in the BG in summer increased 5410 km3 from 2003 to 2010 and decreased at least 210 km3 by 2012. The reduction of both solid and liquid fresh water components indicates a net export of approximately 320 km3 of fresh water from the region occurred between 2010 and 2012, suggesting that the anticyclonic atmosphere‐ocean circulation has weakened.
  10. Manucharyan, Georgy E., and Michael A. Spall. “Wind‐driven freshwater buildup and release in the Beaufort Gyre constrained by mesoscale eddies.” Geophysical Research Letters 43.1 (2016): 273-282[FULL TEXT] Recently, the Beaufort Gyre has accumulated over 20,000 km3 of freshwater in response to strong anticyclonic atmospheric winds that have prevailed over the gyre for almost two decades. Here we explore key physical processes affecting the accumulation and release of freshwater within an idealized eddy‐resolving model of the Beaufort Gyre. We demonstrate that a realistic halocline can be achieved when its deepening tendency due to Ekman pumping is counteracted by the cumulative action of mesoscale eddies. Based on this balance, we derive analytical scalings for the depth of the halocline and its spin‐up time scale and emphasize their explicit dependence on eddy dynamics. Our study further suggests that the Beaufort Gyre is currently in a state of high sensitivity to atmospheric winds. However, an intensification of surface stress would inevitably lead to a saturation of the freshwater content—a constraint inherently set by the intricacies of the mesoscale eddy dynamics.

 

 

 

 

 

 

 

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THIS POST IS A CRITICAL REVIEW OF A YOUTUBE LECTURE ABOUT THE POTENTIAL AGW SEA LEVEL RISE CATASTROPHE OF THE THWAITES GLACIER IN WEST ANTARCTICA  [LINK TO YOUTUBE VIDEO] . IT IS PRESENTED IN THREE PARTS. PART-1 IS A TRANSCRIPT OF THE VIDEO. PART-2 IS A CRITICAL EVALUATION OF THE CLAIMS MADE IN THE VIDEO. PART-3 IS A RELEVANT BIBLIOGRAPHY ON THE SUBJECT.

 

PART-1: TRANSCRIPT OF THE YOUTUBE LECTURE

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  1. Kiya Riverman, University of Oregon glaciologist: If we’re thinking about what sea level is going to look like in 10 years, whether you’re building a dyke around your town or anticipating how far inland to move coastal cities in Florida, this glacier is a big piece of that question (The Thwaites Glacier in West Antarctica).  bandicam 2020-02-09 18-11-08-742
  2. Justin Rowlatt, BBC Environment Correspondent: This is a historic moment. The first  time anyone has tried to drill down through this glacier. Beneath the 600 meters of ice below me is the most important point of all – the point at which the ice meets the ocean water. bandicam 2020-02-09 18-29-59-895
  3. This is ICE-FIN, a NASA funded robot submarine. This is the first time any measurement has been taken beneath what they call the doomsday glacier. Its the first time anyone has seen this – this is the point where the ice meets the warmer ocean water. It’s a place where this huge glacier is rapidly melting. bandicam 2020-02-09 18-42-35-267
  4. Kiya Riverman, University of Oregon glaciologist: So this is very significant because it is huge. And it’s deep! It’s thick. There’s a giant volume of ice here. The bottom of the ice is below sea level. And so that means that it’s very sensitive to change, so the ocean can very easily melt and thin this glacier. bandicam 2020-02-09 18-52-59-600
  5. Justin Rowlatt, BBC Environment Correspondent: So Thwaites Glacier is really remote. It’s right at the heart of the vast basin of ice that’s West Antarctica. The glacier is the size of the UK, it’s the stormiest part of the stormiest continent in the world – and more than a thousand miles from the nearest research station. bandicam 2020-02-09 19-53-19-379
  6. Justin Rowlatt, BBC Environment Correspondent: All this broken ice is more than a hundred miles long. The ice rises almost a mile from the seabed and it’s collapsing into the sea at 2 miles a year. If Thwaites melts it will increase sea levels worldwide by half a meter. But it sits in the middle of the West Antarctic ice sheet and there’s 3 meters more of sea level rise locked up in that. bandicam 2020-02-09 19-59-14-300
  7. Kiya Riverman, University of Oregon glaciologist:  We have just detonated a shot and recorded the energy, the echo from the explosion in order to map the grounding zone to the point where the glacier goes afloat on the ocean. It is changing. It is migrating inland. So this huge reservoir of ice behind us is becoming vulnerable to the ocean melting. What’s happening out there. bandicam 2020-02-09 20-05-16-036
  8. Justin Rowlatt, BBC Environment Correspondent: Let’s be clear. The ice here isn’t going to vanish overnight. It’ll take decades, maybe even centuries for the Thwaites to go, but as the work here has confirmed it is melting increasingly rapidly and that will mean huge changes for us all.

 

 

PART-2: CRITICAL COMMENTARY ON THE YOUTUBE LECTURE

  1. The assessment of the Thwaites Glacier, and the West Antarctic Ice Sheet in general, presented above is the usual AGW climate change interpretation of the observed conditions as described for example in Scambos etal (2017) in the bibliography below. It derives from the observation that the bottom of the Thwaites Glacier is below sea level.
  2. The climate science assessment is that an ongoing rapid loss of ice is observed in this region. This ice loss is a response to changing atmospheric and oceanic conditions brought about by AGW climate change where AGW driven increase in ocean heat content is responsible for the warm water beneath the glacier that’s melting the ice. Models of the ice sheet’s dynamic indicate a potential for accelerated ice loss as ocean-driven melting at the Thwaites Glacier grounding zone leads to thinning, faster flow, and retreat. A complete retreat of the Thwaites Glacier basin would raise global sea level by more than three meters by entraining ice from adjacent catchments“.
  3. The time scale for these events is estimated to be “a few centuries” with a more alarming possibility that faster ice loss could occur through hydrofracture and ice cliff failure, in which case a cataclysmic collapse and sea level rise could happen in a few decades.
  4. This assessment of the observed ice loss from the Thwaites does not take into account known geological features of West Antarctica with significant geothermal heat potential described in a related post [LINK].
  5. The principal geological feature of West Antarctica is the West Antarctic Rift (WAR) and its major fault lines shown in the graphic below. The rift is 700 miles wide and 4,000 miles long with 149 known active volcanoes. A rift is an area where the lithosphere is being pulled apart by plate tectonics. In the diagram below, the black cross hatched area shows the location of the West Antarctic Rift. Red outlines identify regions of volcanic activity with red dots within them showing locations of the volcanoes. Two such red circles that are particularly significant in terms of geological activity and geothermal heat are Deception Island and the Marie Byrd Mantle Plume area. bandicam 2020-02-10 11-51-04-994
  6. As the lithosphere is pulled apart, its middle thins and brings hot mantle rocks closer to the ocean waters and aids in heat transfer from the mantle to the ocean. See graphic below provided by the University of Sydney [LINK]. Here, the color red indicates intensity of geothermal heat. The WAR contains 149 active volcanoes.bandicam 2020-02-10 12-03-35-146
  7. Within this giant rift structure are specific regions of intense geological activity and geothermal heat. The Northwest extension of the WAR, with a string of active volcanoes, goes into the Antarctic Peninsula and out into the ocean. The West Antarctic Rift (WAR) consists of a number of rift valleys between East and West Antarctica. A rift valley is a lowland region that forms in the middle where a rift occurs. They tend to be long, narrow, and deep. The WAR includes the Byrd area of West Antarctica. The Byrd area is the main portion of the WAR.
  8. The Marie Byrd Mantle Plume Hotspot is shown below. It includes the Thwaites Glacier and the Pine Island Glacier. A mantle plume hotspot is a large area where magma comes up from the mantle of the inner earth, goes up through layers of rock until obstructed when it spreads out into a mushroom shape over a widespread area. If it is under a sufficient pressure, the magma can break through to the atmosphere as a volcanic eruption. The shaded red areas on the map are graphical representations of NASA ice melt data from 1992-2019. Red shaded areas identify locations of melting and the darker the red color, the more intense the melting. These red areas are found close to the edge of the Marie Byrd Mantle Plume. These data suggest that the mantle plume is the cause of the observed ice melt. marie-byrd-mantle-plume
  9. A rise in elevation has been observed in the Marie Byrd Mantle Plume area It could be that the bedrock is being pushed up by the underlying magma although some of the elevation rise is likely due to “glacial rebound” –  (when ice melts and meltwater runs off it reduces the pressure on the underlying structure and causes it to rise). We note here that the Thwaites Glacier is located within Marie Byrd Mantle Plume Hotspot area in a region of extensive ice melt during 1992-2019.
  10. The image below shows the the Pine Island Glacier and the much larger Thwaites Glacier areas cross hatched in blue lines. Red circles show locations of known active volcanoes underneath the glacier. It is claimed in this video – and in the media in general, that they have discovered a huge air cavity beneath the ice and above the bedrock surface in the Thwaites Glacier that is evidence of the impact of AGW on the Thwaites Glacier. However, the more likely creator of that cavity is an eruption of any of the 40 active volcanoes known to exist underneath the Thwaites Glacier.

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THE RELEVANT BIBLIOGRAPHY

A bibliography of research papers 1993-2019 on the subject of the Thwaites Glacier is included below. Many of the papers support the climate change theory of mass loss from the Thwaites glacier by way of a warm ocean (warmed by AGW) eating away at the bottom of the volcano that dips into the ocean. Scambos (2017) is an example. There are a few others. However, the ability of the atmosphere through AGW to warm the deep ocean contains inconsistencies noted by several authors in the bibliography and also in a related post [LINK] . In the bibliography we find many of the authors have acknowledged these difficulties and have presented evidence of geothermal heat as the source of energy that warms the water that melts the glacier. (dVries 2018), (Fisher 2015), (Damiani 2014), (Schroeder 2014), (Maule 2005), and (Corr 2008) are examples.

 

CONCLUSION: We find that the presentation of the geological features of West Antarctica in terms of the West Antarctic Rift, the Marie Byrd Mantle Plume, and evidence of active volcanism underneath the Thwaites Glacier provide evidence that the role of geothermal heat in the evaluation of the ice melt dynamics of the Thwaites Glacier cannot be ignored. The geothermal heat flux data and their analysis in terms of the Thwaites glacier dynamics in the literature is generally supportive of that view. In consideration of the above we find it unlikely that ice melt at the bottom of the Thwaites Glacier can be understood in terms of AGW climate change as claimed in the video lecture presented above.

 

 

 

THWAITES GLACIER BIBLIOGRAPHY 1993-2018

  1. Blankenship, Donald et al. “Active volcanism beneath the West Antarctic ice sheet & implications for ice-sheet stability.” Nature 361.6412 (1993): It is widely understood that the collapse of the West Antarctic ice sheet (WAIS) would cause a global sea level rise of 6 m, yet there continues to be considerable debate about the detailed response of this ice sheet to climate change. Because its bed is grounded well below sea level, the stability of the WAIS may depend on geologically controlled conditions at the base which are independent of climate. In particular, heat supplied to the base of the ice sheet could increase basal melting and thereby trigger ice streaming, by providing the water for a lubricating basal layer of till on which ice streams are thought to slide4,5. Ice streams act to protect the reservoir of slowly moving inland ice from exposure to oceanic degradation, thus enhancing ice-sheet stability. Here we present aerogeophysical evidence for active volcanism and associated elevated heat flow beneath the WAIS near the critical region where ice streaming begins. If this heat flow is indeed controlling ice-stream formation, then penetration of ocean waters inland of the thin hot crust of the active portion of the West Antarctic rift system could lead to the disappearance of ice streams, and possibly trigger a collapse of the inland ice reservoir.
  2. Behrendt, John C., et al. “Aeromagnetic evidence for a volcanic caldera (?) complex beneath the divide of the West Antarctic Ice Sheet.” Geophysical Research Letters 25.23 (1998): 4385-4388.  A 1995–96 aeromagnetic survey over part of the Sinuous Ridge (SR) beneath the West Antarctic Ice Sheet (WAIS) divide shows a 70‐km diameter circular pattern of 400–1200‐nT anomalies suggesting one of the largest volcanic caldera(?) complexes on earth. Radar‐ice‐sounding (RIS) shows the northern part of this pattern overlies the SR, and extends south over the Bentley Subglacial Trench (BST). Modeled sources of all but one the caldera(?) anomalies are at the base of <1–2‐km thick ice and their volcanic edifices have been glacially removed. The exception is a 700‐m high, 15‐km wide “volcano” producing an 800‐nT anomaly over the BST. “Intrusion” of this “volcano” beneath 3 km of ice probably resulted in pillow basalt rather than easily removed hyaloclastite erupted beneath thinner ice. The background area (−300 to −500‐nT) surrounding the caldera(?) is possibly caused by a shallow Curie isotherm. We suggest uplift of the SR forced the advance of the WAIS.
  3. Dalziel, I. W. D., and L. A. Lawver. “The lithospheric setting of the West Antarctic ice sheet.” The West Antarctic Ice Sheet: Behavior and Environment, Antarct. Res. Ser 77 (2001): 29-44[FULL TEXT PDF]bandicam 2020-02-10 11-08-44-341
  4. Rignot, Eric, et al. “Acceleration of Pine island and Thwaites glaciers, west Antarctica.” Annals of Glaciology 34 (2002): 189-194.  Recent satellite investigations revealed that in the 1990s the grounding line of Pine Island and Thwaites Glaciers, West Antarctica, retreated several km, the ice surface on the interior of the basins lowered 10 cm a–1, and Pine Island Glacier thinned 1.6 ma–1. These observations, however, were not sufficient to determine the cause of the changes. Here, we present satellite radar interferometry data that show the thinning and retreat of Pine Island Glacier are caused by an acceleration of ice flow of about 18 ± 2% in 8 years. Thwaites Glacier maintained a nearly constant flow regime at its center, but widened along the sides, and increased its 30 ± 15% mass deficit by another 4% in 4 years. The combined mass loss from both glaciers, if correct, contributes an estimated 0.08 ± 0.03 mma–1 global sea-level rise in 2000.
  5. Engelhardt, Hermann. “Ice temperature and high geothermal flux at Siple Dome, West Antarctica, from borehole measurements.” Journal of Glaciology 50.169 (2004): 251-256A vertical temperature profile through the West Antarctic ice sheet (WAIS) at the summit of Siple Dome reveals an elevated geothermal flux. This could be the root cause for the existence of a dynamic ice-stream system in the WAIS. Siple Dome is still frozen on its bed, but adjacent ice streams have bed temperatures at the pressure-melting point of ice. Although present-day temperature increases due to climatic change do not have an immediate effect on the basal conditions that control the velocity of the ice, indirect effects like a rapid disintegration of the floating ice shelves or additional melt-water input at the surface could give rise to speed-up of the ice streams with an ensuing rise in sea level. Ongoing melt at the base of the ice and changes at the margins will allow continued rapid flow of the ice streams with a possibility of disintegration, within a relatively short period of time, of at least part of the WAIS.
  6. Maule, Cathrine Fox, et al. “Heat flux anomalies in Antarctica revealed by satellite magnetic data.” Science 309.5733 (2005): 464-467The geothermal heat flux is an important factor in the dynamics of ice sheets; it affects the occurrence of subglacial lakes, the onset of ice streams, and mass losses from the ice sheet base. Because direct heat flux measurements in ice-covered regions are difficult to obtain, we developed a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have ice streams.
  7. Vaughan, David G., et al. “New boundary conditions for the West Antarctic ice sheet: Subglacial topography beneath Pine Island Glacier.” Geophysical Research Letters 33.9 (2006).  Predictions about future changes in the Amundsen Sea sector of the West Antarctic ice sheet (WAIS) have been hampered by poorly known subglacial topography. Extensive airborne survey has allowed us to derive improved subglacial topography for the Pine Island Glacier basin. The trunk of this glacier lies in a narrow, 250‐km long, 500‐m deep sub‐glacial trough, suggesting a long‐lived and constrained ice stream. Two tributaries lie in similar troughs, others lie in less defined, shallower troughs. The lower basin of the glacier is surrounded by bedrock, which, after deglaciation and isostatic rebound, could rise above sea level. This feature would impede ice‐sheet collapse initiated near the grounding line of this glacier, and prevent its progress into the deepest portions of WAIS. The inland‐slope of the bed beneath the trunk of the glacier, however, confirms potential instability of the lower basin, containing sufficient ice to raise global sea by ∼24 cm.
  8. Holt, John W., et al. “New boundary conditions for the West Antarctic Ice Sheet: Subglacial topography of the Thwaites and Smith glacier catchments.” Geophysical Research Letters 33.9 (2006)Airborne radar sounding over the Thwaites Glacier (TG) catchment and its surroundings provides the first comprehensive view of subglacial topography in this dynamic part of the West Antarctic Ice Sheet (WAIS) and reveals that TG is underlain by a single, broad basin fed by a dendritic pattern of valleys, while Smith Glacier lies within an extremely deep, narrow trench. Subglacial topography in the TG catchment slopes inland from a broad, low‐relief coastal sill to the thickest ice of the WAIS and makes deep connections to both Pine Island Glacier and the Ross Sea Embayment enabling dynamic interactions across the WAIS during deglaciation. Simple isostatic rebound modeling shows that most of this landscape would be submarine after deglaciation, aside from an island chain near the present‐day Ross‐Amundsen ice divide. The lack of topographic confinement along TG’s eastern margin implies that it may continue to widen in response to grounding line retreat.
  9. Vogel, Stefan W., and Slawek Tulaczyk. “Ice‐dynamical constraints on the existence and impact of subglacial volcanism on West Antarctic Ice Sheet stability.” Geophysical Research Letters 33.23 (2006)Subglacial volcanism in West Antarctica may play a crucial role in the dynamics and stability of the West Antarctic Ice Sheet (WAIS). Evidence supporting the existence of an individual subglacial volcanic center (Mt. Casertz) in the upper catchments of Whillans and Kamb Ice Stream (WIS and KIS), comes from a comparison of ice sheet modeling results with measured ice velocities. Lubrication of an area, which otherwise should be frozen to its bed, is best explained by basal melt water generated in the vicinity of Mt. Casertz. The estimated melt water production of Mt. Casertz corresponds to ∼8 % of the total melt water production in the two catchments. This would be sufficient to offset basal freezing in the dormant KIS, relubricating its bed and potentially causing a restart. Near future volcanic activity changes are speculative, but would have far reaching implications on the dynamics and stability of the WAIS requiring further investigation.
  10. Banta, J. Ryan, et al. “Spatial and temporal variability in snow accumulation at the West Antarctic Ice Sheet Divide over recent centuries.” Journal of Geophysical Research: Atmospheres 113.D23 (2008).  Ice cores collected in 2000 (ITASE 00‐1) and 2005 (WDC05A, WDC05Q) from the West Antarctic Ice Sheet Divide (WAIS Divide) project site were used to investigate the spatial and temporal variability in accumulation. The ice cores were dated based on annual layer counting of multiple glaciochemical measurements resulting in bottom depth ages for WDC05A, WDC05Q, and ITASE 00‐1 of 1775, 1521, and 1653 A.D., with mean annual accumulation rates of 0.200, 0.204, and 0.221 mweq a−1, respectively. Small‐scale spatial variability (SSV) was determined using an analysis of variance of accumulation in the ice core array, thereby quantifying the uncertainty in individual accumulation records. Results indicate that the spatial variability was 0.030 mweq a−1, or approximately 15% of the average annual accumulation. An accumulation record representative of the WAIS Divide local area over recent centuries was developed using a principal component analysis to identify the coherent accumulation signal. The WAIS Divide local record exhibited 14% interannual variability (1 standard deviation of the mean) with the SSV reduced to 0.017 mweq a−1. Correlations of the WAIS Divide local accumulation record with atmospheric indices (e.g., Antarctic Oscillation) exhibited periods when the records oscillate in and out of phase. Thus, reconstructing local and global atmospheric indices from WAIS Divide accumulation records over recent centuries may prove problematic.
  11. Corr, Hugh FJ, and David G. Vaughan. “A recent volcanic eruption beneath the West Antarctic ice sheet.” Nature Geoscience 1.2 (2008): 122-125.  Indirect evidence suggests that volcanic activity occurring beneath the West Antarctic ice sheet influences ice flow and sheet stability1,2,3. However, only volcanoes that protrude through the ice sheet4 and those inferred from geophysical techniques1,2 have been mapped so far. Here we analyse radar data from the Hudson Mountains, West Antarctica5, that contain reflections from within the ice that had previously been interpreted erroneously as the ice-sheet bed. We show that the reflections are present within an elliptical area of about 23,000 km2 that contains tephra (solid rock pieces in volcanic ejections) from an explosive volcanic eruption. The tephra layer is thickest at a subglacial topographic high, which we term the Hudson Mountains Subglacial Volcano. The layer depth dates the eruption at 207 BC±240 years, which matches exceptionally strong but previously unattributed conductivity signals in nearby ice cores. The layer contains 0.019–0.31 km3 of tephra, which implies a volcanic explosive index of 3–4. Production and episodic release of water from the volcano probably affected ice flow at the time of the eruption. Ongoing volcanic heat production may have implications for contemporary ice dynamics in this glacial system.
  12. Joughin, Ian, et al. “Basal conditions for Pine Island and Thwaites Glaciers, West Antarctica, determined using satellite and airborne data.” Journal of Glaciology 55.190 (2009): 245-257. We use models constrained by remotely sensed data from Pine Island and Thwaites Glaciers, West Antarctica, to infer basal properties that are difficult to observe directly. The results indicate strong basal melting in areas upstream of the grounding lines of both glaciers, where the ice flow is fast and the basal shear stress is large. Farther inland, we find that both glaciers have ‘mixed’ bed conditions, with extensive areas of both bedrock and weak till. In particular, there are weak areas along much of Pine Island Glacier’s main trunk that could prove unstable if it retreats past the band of strong bed just above its current grounding line. In agreement with earlier studies, our forward ice-stream model shows a strong sensitivity to small perturbations in the grounding line position. These results also reveal a large sensitivity to the assumed bed (sliding or deforming) model, with non-linear sliding laws producing substantially greater dynamic response than earlier simulations that assume a linear-viscous till rheology. Finally, comparison indicates that our results using a plastic bed are compatible with the limited observational constraints and theoretical work that suggests an upper bound exists on maximum basal shear stress.
  13. Tinto, K. J., and Robin E. Bell. “Progressive unpinning of Thwaites Glacier from newly identified offshore ridge: Constraints from aerogravity.” Geophysical Research Letters 38.20 (2011) A new bathymetric model from the Thwaites Glacier region based on IceBridge airborne gravity data defines morphologic features that exert key controls on the evolution of the ice flow. A prominent ridge with two distinct peaks has been identified 40 km in front of the present‐day grounding line, undulating between 300–700 m below sea level with an average relief of 700 m. Presently, the Thwaites ice shelf is pinned on the eastern peak. More extensive pinning in the past would have restricted flow of floating ice across the full width of the Thwaites Glacier system. At present thinning rates, ice would have lost contact with the western part of the ridge between 55–150 years ago, allowing unconfined flow of floating ice and contributing to the present‐day mass imbalance of Thwaites Glacier. The bathymetric model also reveals a 1200 m deep trough beneath a bight in the grounding line where the glacier is moving the fastest. This newly defined trough marks the lowest topographic pathway to the Byrd Subglacial Basin, and the most likely path for future grounding line retreat.
  14. Larour, E., et al. “Ice flow sensitivity to geothermal heat flux of Pine Island Glacier, Antarctica.” Journal of Geophysical Research: Earth Surface 117.F4 (2012)Model projections of ice flow in a changing climate are dependent on model inputs such as surface elevation, bedrock position or surface temperatures, among others. Of all these inputs, geothermal heat flux is the one for which uncertainty is greatest. In the area of Pine Island Glacier, Antarctica, available data sets differ by up to a factor of 2.5. Here, we evaluate the impact of such uncertainty on ice flow, using sampling analyses based on the Latin‐Hypercube method. First, we quantify the impact of geothermal heat flux errors on ice hardness, a thermal parameter that critically controls the magnitude of ice flow. Second, we quantify the impact of the same errors on mass balance, specifically on the mass flux advecting through thirteen fluxgates distributed across Pine Island Glacier. We contrast our results with similar uncertainties generated by errors in the specification of ice thickness. Model outputs indicate that geothermal heat flux errors yield uncertainties on ice hardness on the order of 5–7%, with maximum uncertainty reaching 15%. Resulting uncertainties in mass balance remain however below 1%. We discuss the uncertainty distribution and its relationship to the amount of heat available at the base of the ice sheet from friction, viscous and geothermal heating. We also show that comparatively, errors in ice thickness contribute more to model uncertainty than errors in geothermal heat flux for fast‐flowing ice streams. [FULL TEXT]
  15. Schroeder, Dustin M., et al. “Estimating subglacial water geometry using radar bed echo specularity: application to Thwaites Glacier, West Antarctica.” IEEE Geoscience and Remote Sensing Letters 12.3 (2014A): 443-447.  Airborne radar sounding is an established tool for observing the bed conditions and subglacial hydrology of ice sheets and glaciers. The specularity content of radar bed echoes has also been used to detect the hydrologic transition of a subglacial water system from a network of distributed canals to a network of concentrated channels beneath the Thwaites Glacier. However, the physical dimensions of the distributed water bodies in these networks have not been constrained by observations. In this letter, we use a variety of simple radar scattering, attenuation, and cross-sectional models to provide a first estimate of the subglacial water body geometries capable of producing the observed anisotropic specularity of the Thwaites Glacier catchment. This approach leads to estimates of ice/water interface root mean square roughnesses less than about 15 cm, thicknesses of more than about 5 cm, lengths of more than about 15 m, and widths between about 0.5 and 5 m.
  16. Schroeder, Dustin M., et al. “Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet.” Proceedings of the National Academy of Sciences 111.25 (2014B): 9070-9072.  Heterogeneous hydrologic, lithologic, and geologic basal boundary conditions can exert strong control on the evolution, stability, and sea level contribution of marine ice sheets. Geothermal flux is one of the most dynamically critical ice sheet boundary conditions but is extremely difficult to constrain at the scale required to understand and predict the behavior of rapidly changing glaciers. This lack of observational constraint on geothermal flux is particularly problematic for the glacier catchments of the West Antarctic Ice Sheet within the low topography of the West Antarctic Rift System where geothermal fluxes are expected to be high, heterogeneous, and possibly transient. We use airborne radar sounding data with a subglacial water routing model to estimate the distribution of basal melting and geothermal flux beneath Thwaites Glacier, West Antarctica. We show that the Thwaites Glacier catchment has a minimum average geothermal flux of ∼114 ± 10 mW/m2 with areas of high flux exceeding 200 mW/m2 consistent with hypothesized rift-associated magmatic migration and volcanism. These areas of highest geothermal flux include the westernmost tributary of Thwaites Glacier adjacent to the subaerial Mount Takahe volcano and the upper reaches of the central tributary near the West Antarctic Ice Sheet Divide ice core drilling site.
  17. Damiani, Theresa M., et al. “Variable crustal thickness beneath Thwaites Glacier revealed from airborne gravimetry, possible implications for geothermal heat flux in West Antarctica.” Earth and Planetary Science Letters 407 (2014): 109-122Thwaites Glacier has one of the largest glacial catchments in West Antarctica. The future stability of Thwaites Glacier’s catchment is of great concern, as this part of the West Antarctic Ice Sheet has recently been hypothesized to already be en route towards collapse. Although an oceanic trigger is thought to be responsible for current change at the grounding line of Thwaites Glacier, in order to determine the effects of this coastal change further in the interior of the West Antarctic Ice Sheet it is essential to also better constrain basal conditions that control the dynamics of fast glacial flow within the catchment itself. One major contributor to fast glacial flow is the presence of subglacial water, the production of which is a result of both glaciological shear heating and geothermal heat flux. The primary goal of our study is to investigate the crustal thickness beneath Thwaites Glacier, which is an important contributor to regional-scale geothermal heat flux patterns. Crustal structure is an indicator of past tectonic events and hence provides a geophysical proxy for the thermal status of the crust and mantle. Terrain-corrected Bouguer gravity disturbances are used here to estimate depths to the Moho and mid-crustal boundary. The thin continental crust we reveal beneath Thwaites Glacier supports the hypothesis that the West Antarctic Rift System underlies the region and is expressed topographically as the Byrd Subglacial Basin. This rifted crust is of similar thickness to that calculated from airborne gravity data beneath neighboring Pine Island Glacier, and is more extended than crust in the adjacent Siple Coast sector of the Ross Sea Embayment. A zone of thinner crust is also identified near the area’s subaerial volcanoes lending support to a recent interpretation predicting that this part of Marie Byrd Land is a major volcanic dome, likely within the West Antarctic Rift System itself. Near-zero Bouguer gravity disturbances for the subglacial highlands and subaerial volcanoes indicate the absence of supporting crustal roots, suggesting either (1) thermal support from a warm lithosphere or alternatively, and arguably less likely; (2) flexural support of the topography by a cool and rigid lithosphere, or (3) Pratt-like compensation. Although forward modeling of gravity data is non-unique in respect to these alternative possibilities, we prefer the hypothesis that Marie Byrd Land volcanoes are thermally-supported by warmer upper mantle. The presence of such inferred warm upper mantle also suggests regionally elevated geothermal heat flux in this sector of the West Antarctic Rift System and consequently the potential for enhanced meltwater production beneath parts of Thwaites Glacier itself. Our new crustal thickness estimates and geothermal heat flux inferences in the Thwaites Glacier region are significant both for studies of the structure of the broader West Antarctic Rift System and for assessments of geological influences on West Antarctic Ice Sheet dynamics and glacial isostatic adjustment models.
  18. Fisher, Andrew T., et al. “High geothermal heat flux measured below the West Antarctic Ice Sheet.” Science advances 1.6 (2015): e1500093.  The geothermal heat flux is a critical thermal boundary condition that influences the melting, flow, and mass balance of ice sheets, but measurements of this parameter are difficult to make in ice-covered regions. We report the first direct measurement of geothermal heat flux into the base of the West Antarctic Ice Sheet (WAIS), below Subglacial Lake Whillans, determined from the thermal gradient and the thermal conductivity of sediment under the lake. The heat flux at this site is 285 ± 80 mW/m2, significantly higher than the continental and regional averages estimated for this site using regional geophysical and glaciological models. Independent temperature measurements in the ice indicate an upward heat flux through the WAIS of 105 ± 13 mW/m2. The difference between these heat flux values could contribute to basal melting and/or be advected from Subglacial Lake Whillans by flowing water. The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region.
  19. Scambos, Ted A., et al. “How much, how fast?: A science review and outlook for research on the instability of Antarctica’s Thwaites Glacier in the 21st century.” Global and Planetary Change 153 (2017): 16-34.  Constraining how much and how fast the West Antarctic Ice Sheet (WAIS) will change in the coming decades has recently been identified as the highest priority in Antarctic research (National Academies, 2015). Here we review recent research on WAIS and outline further scientific objectives for the area now identified as the most likely to undergo near-term significant change: Thwaites Glacier and the adjacent Amundsen Sea. Multiple lines of evidence point to an ongoing rapid loss of ice in this region in response to changing atmospheric and oceanic conditions. Models of the ice sheet’s dynamic behavior indicate a potential for greatly accelerated ice loss as ocean-driven melting at the Thwaites Glacier grounding zone and nearby areas leads to thinning, faster flow, and retreat. A complete retreat of the Thwaites Glacier basin would raise global sea level by more than three meters by entraining ice from adjacent catchments. This scenario could occur over the next few centuries, and faster ice loss could occur through processes omitted from most ice flow models such as hydrofracture and ice cliff failure, which have been observed in recent rapid ice retreats elsewhere. Increased basal melt at the grounding zone and increased potential for hydrofracture due to enhanced surface melt could initiate a more rapid collapse of Thwaites Glacier within the next few decades. 
  20. de Vries, Maximillian van Wyk, Robert G. Bingham, and Andrew S. Hein. “A new volcanic province: an inventory of subglacial volcanoes in West Antarctica.” Geological Society, London, Special Publications 461.1 (2018): 231-248[FULL TEXT]  The West Antarctic Ice Sheet overlies the West Antarctic Rift System about which, due to the comprehensive ice cover, we have only limited and sporadic knowledge of volcanic activity and its extent. Improving our understanding of subglacial volcanic activity across the province is important both for helping to constrain how volcanism and rifting may have influenced ice-sheet growth and decay over previous glacial cycles, and in light of concerns over whether enhanced geothermal heat fluxes and subglacial melting may contribute to instability of the West Antarctic Ice Sheet. Here, we use ice-sheet bed-elevation data to locate individual conical edifices protruding upwards into the ice across West Antarctica, and we propose that these edifices represent subglacial volcanoes. We used aeromagnetic, aerogravity, satellite imagery and databases of confirmed volcanoes to support this interpretation. The overall result presented here constitutes a first inventory of West Antarctica’s subglacial volcanism. We identified 138 volcanoes, 91 of which have not previously been identified, and which are widely distributed throughout the deep basins of West Antarctica, but are especially concentrated and orientated along the >3000 km central axis of the West Antarctic Rift System.

 

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THIS POST IS A CRITICAL REVIEW OF A FEB 7 2020 CNBC REPORT ON ANTARCICA : “Antarctica registers hottest temperature ever at nearly 65 degrees Fahrenheit” [LINK]

A VIDEO VERSION OF THIS ALARMING TEMPERATURE MEASUREMENT IS AVAILABLE ON YOUTUBE [LINK]

THE REPORT INCLUDES THE FOLLOWING INFORMATION.

  1. “Antarctica just set its hottest temperature ever recorded at 64.9 degrees Fahrenheit as climate change continues to accelerate across the world. The reading beats the continent’s previous record of 63.5 degrees tallied in March 2015 and comes shortly after the Earth saw its hottest January on record and hottest decade on record in the 2010s. The reading was taken at the Esperanza Base along Antarctica’s Trinity Peninsula on Thursday”.
  2. “Scientists say that they see no end to the way climate change continues to shatter temperature records across the world, including in Antarctica, which is one of the fastest-warming regions in the world. Research shows that Antarctica’s glaciers are rapidly melting as the planet warms, releasing enough water to significantly raise global sea levels. The amount of ice lost each year from the Antarctic ice sheet increased at least sixfold between 1979 and 2017, according to the WMO. Roughly 87% of glaciers along the west coast of the Antarctic Peninsula have retreated over the last half-century, with most showing an accelerated retreat in the last 12 years. The peninsula is expected to see additional extreme warmth in the upcoming days”.

 

CRITICAL COMMENTARY ON THIS REPORT IS OFFERED BELOW.

The message appears to be that Antarctica has been hit hard by AGW climate change and that is causing the icy continent to melt and raise sea levels. Here we provide some details about Antarctica that are inconsistent with this assessment. Firstly, it is noted that the high temperature of 65F (18.3C) was measured not as the mean surface temperature for the continent of Antarctica but at the Esperanza Base located in a tiny corner of the continent. In the map of Antarctica at the top of this post, Esperanza Base is located in the uppermost and leftmost corner at the tip of the Antarctic Peninsula. This specific location cannot be considered to be representative of Antarctica as a whole in any way whatsoever particularly so because this region is geologically active. Isolated heat events of this kind are also known to be created in the Antarctic Peninsula region by the effects Foehn and Chinook winds known to occur in this region [LINK] [LINK]

In terms of mean surface temperature for the continent we present below two GIF animation charts in Figure 1 that compare the lower troposphere temperatures 1979-2019 above Antarctica (on the left) with with those above the Arctic (on the right). These temperatures represent the mean temperature across the two regions rather than an arbitrary location such as the Esperanza Base at the tip of the geologically active Antarctic Peninsula. The GIF animations cycle through the twelve calendar months showing one calendar month at a time. It is noted in these charts that the warming trends vary a great deal among the calendar months and that the warming is much stronger in the Arctic than on Antarctica.

This comparison is made clearer in Figure 2 where the OLS linear regression trends and the R-squared value for those trends are tabulated and averaged for the twelve calendar months. The annual averages for all twelve calendar  months show a high warming rate and a high R-squared value for the Arctic indicating strong statistically significant warming in that region. However, no significant warming is seen in Antarctica where the annual average values show very low annual average warming rate and also very low annual average R-squared value.

The mean annual warming rate in the Arctic is found to be 7.5 times the mean annual warming rate in Antarctica; and the statistical significance of the warming rate, as measured by R-Squared, is found to be 10.4 times higher in the Arctic than in Antarctica. These results indicate very little if any evidence of AGW climate change in Antarctica and demonstrate a generally accepted climate state of Antarctica in which AGW global warming is not a significant factor that should guide the interpretation of temperature and ice melt in Antarctica. It is also noted that temperature data from weather stations in Antarctica are available from the British Antarctic Survey 1957-2008. The Antarctic Peninsula stations (eg. Faraday and Esperanza) do show a warming trend in these data but the eastern and central weather stations (eg. Amundsen-Scott, Halley, Mirny, and Dumont) show either no temperature trend at all or a slight cooling trend [LINK] .

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FIGURE 1: TEMPERATURE 1979-2019: ANTARCTICA & THE ARCTIC COMPARED

 

FIGURE 2: WARMING RATE: ANTARCTIC VS ARCTIC

ZZZTABLE

 

 

GEOLOGICAL FEATURES OF THE ANTARCTIC PENINSULA

In a related post on this site [LINK]  is shown an almost comical history of desperate but failed attempts to describe temperature and ice melt events in Antarctica as dramatic and alarming impacts of AGW (anthropogenic global warming) and climate change. The reason for the failure of this line of reasoning in climate science is found in another related post [LINK]  where the relevant geological features of Antarctica are described and shown to provide a more rational explanation of the localized and isolated but dramatic temperature and ice melt events that have been and continue to be arbitrarily attributed to AGW climate change. It is noteworthy that these attributions are made not only by the media but also by the climate scientists themselves although many published papers in this area point out the anomalies in this assumed attribution, as seen in the bibliography provided at the end of this post. For example, in Ludescher (2016) the author points out gross anomalies in the attribution of Antarctic temperatures trends to AGW climate change; and in Hansen (2005), the venerable father of the modern form of fear based climate alarmism struggles to find a way to relate Antarctica ice melt events to AGW climate change but acknowledges the difficulties in that interpretation. On the other side we see papers like Hanna (1996) and Vaughan(2003), where researchers identify the difficulties in the attribution of Antarctica temperatures and ice melt to AGW climate change but struggle to find a way to make that attribution anyway; while Overland 2008 provides a similar comparison of the Arctic with Antarctica described above in this post.

With respect to the specific issue of the temperature measurement at Esperanza Base in January of 2020 of 65 Fahrenheit that is claimed to be evidence of the impact of AGW climate change on Antarctica, we describe here some details of the geology and prior geological history of this specific region of Antarctica. The image in Figure 3 below shows a NASA graph that reflects ice melt data for the entire continent from 2003-2008. It shows that Antarctica as a whole gained ice at the rate of 82 gigatonnes/year (GTY). However, East Antarctica, which composes 80% of the continent, gained 136 GTY. This means that West Antarctica, 20% of the continent, lost 54 GTY. Of that 29 GTY of the melt, more than half, occurred in the Antarctic Peninsula where Esperanza Base is located. It is not possible for a uniform atmospheric cause such as AGW climate change to create such vastly different localized ice melt events.

FIGURE 3: ANTARCTICA ICE MELT DATA 2003-2008zwally2

 

As described in greater detail in a related post [LINK] , West Antarctica, particularly so the Antarctic Peninsula, is geologically very active with extensive regions of extreme volcanic activity that provide more convincing  explanations of isolated high temperature and ice melt events than the “slippery slope” of the AGW explanation as described by James Hansen (Hansen 2005). Some of these geological features are displayed in Figure 4 where the region marked with black hatched lines is the 700 miles wide by 4,000 miles long West Antarctic Rift (WAR). A rift is a region where the lithosphere is being pulled apart by plate tectonics. The lithosphere is the solid outermost layer of the upper mantle (along with the crust). These are regions of extreme geological activity and geothermal heat such that the WAR, home to about 200 land and submarine volcanoes, has created a hotspot that is 620,000 square miles in area. If  we zoom into the South Shetland Island portion of the rift, we find ourselves in the tip of the Antarctic Peninsula where Esperanza Base is located (Figure 5). This region includes the geological hot-spot of the Deception Island Collapse Caldera, a huge volcanic eruption so violent that the middle of the volcano collapses into a hollow region such that geologically heated warm water can create a giant hot tub where tourists to Antarctica can explore in swimsuits as seen in Figure 6.

 

CONCLUSION: We conclude from the above analysis, the data presented, and the relevant bibliography shown below, that an extreme temperature event of 18C observed at a single point in time in a specific location on the tip of the Antarctic Peninsula, a region known to be highly geologically active, does not serve as evidence of AGW climate change or its impacts on Antarctica. Arbitrary attributions of this kind to AGW are likely driven by activism needs and confirmation bias [LINK] . They have no interpretation in terms of AGW climate change and they do not conform to the requirements of objective scientific inquiry. An added consideration in the interpretation of isolated and short term temperature events is that the Antarctic Peninsula is known to experience Foehn and Chinook winds that can create exactly the kind of temperature event described. 

 

FIGURE 4: GEOLOGICAL FEATURES OF ANTARCTICA

bandicam 2020-02-09 11-41-59-086

 

 

FIGURE 5: THE ANTARCTIC PENINSULA

bandicam 2020-02-09 11-59-48-710

 

FIGURE 6: ANTARCTICA TOURISM 

bandicam 2020-02-09 12-19-23-705

 

 

THE RELEVANT BIBLIOGRAPHY
  1. Hanna, Edward. “The role of Antarctic sea ice in global climate change.” Progress in physical geography 20.4 (1996): 371-401.  Taking a distinct interdisciplinary focus, a critical view is presented of the current state of research concerning Antarctic sea-ice / atmosphere / ocean interaction and its effect on climate on the interannual timescale, with particular regard to anthropogenic global warming. Sea-ice formation, morphology, thickness, extent, seasonality and distribution are introduced as vital factors in climatic feedbacks. Sea-ice / atmosphere interaction is next discussed, emphasizing its meteorological and topographical influences and the effects of and on polar cyclonic activity. This leads on to the central theme of sea ice in global climate change, which contains critiques of sea-ice climatic feedbacks, current findings on the representation of these feedbacks in global climatic models, and to what extent they are corroborated by observational evidence. Sea-ice / ocean interaction is particularly important. This is discussed with special reference to polynyas and leads, and the use of suitably coupled sea-ice / ocean models. A brief review of several possible climatic forcing factors is presented, which most highly rates a postulated ENSO-Antarctic sea-ice link. Sea-ice / atmosphere / ocean models need to be validated by adequate observations, both from satellites and ground based. In particular, models developed in the Arctic, where the observational network allows more reasonable validation, can be applied to the Antarctic in suitably modified form so as to account for unique features of the Antarctic cryosphere. Benefits in climatic modelling will be gained by treating Antarctic sea ice as a fully coupled component of global climate.
  2. Vaughan, David G., et al. “Recent rapid regional climate warming on the Antarctic Peninsula.” Climatic change 60.3 (2003): 243-274.  The IPCC) confirmed that mean global warming was 0.6 ± 0.2 °C during the 20th century and cited anthropogenic increases in greenhouse gases as the likely cause of temperature rise in the last 50 years. But this mean value conceals the substantial complexity of observed climate change, which is seasonally- and diurnally-biased, decadally-variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming, which was substantially more rapid than the global mean. However, each RRR warming occupies a different climatic regime and may have an entirely different underlying cause. We discuss the significance of RRR warming in one area, the Antarctic Peninsula. Here warming was much more rapid than in the rest of Antarctica where it was not significantly different to the global mean. We highlight climate proxies that appear to show that RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia, and so unlikely to be a natural mode of variability. So while the station records do not indicate a ubiquitous polar amplification of global warming, the RRR warming on the Antarctic Peninsula might be a regional amplification of such warming. This, however, remains unproven since we cannot yet be sure what mechanism leads to such an amplification. We discuss several possible candidate mechanisms: changing oceanographic or changing atmospheric circulation, or a regional air-sea-ice feedback amplifying greenhouse warming. We can show that atmospheric warming and reduction in sea-ice duration coincide in a small area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process is the probable cause of RRR warming on the Antarctic Peninsula and until the mechanism initiating and sustaining the RRR warming is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.
  3. Hansen, James E. “A slippery slope: How much global warming constitutes “dangerous anthropogenic interference”?.” Climatic Change 68.3 (2005): 269-279. In a recent article (Hansen, 2004) I included a photograph taken by Roger Braithwaite with a rushing stream pouring into a hole in the Greenland ice sheet. The photo relates to my contention that disintegration of ice sheets is a wet, potentially rapid, process, and consequent sea level rise sets a low limit on the global warming that can be tolerated without risking dangerous anthropogenic interference with climate. I asked glaciologist Jay Zwally if I would be crucified for a caption such as: “On a slippery slope to Hell, a stream of snowmelt cascades down a moulin on the Greenland ice sheet. The moulin, a near-vertical shaft worn in the ice by surface water, carries water to the base of the ice sheet. There the water is a lubricating fluid that speeds motion and disintegration of the ice sheet. Ice sheet growth is a mslow dry process, inherently limited by the snowfall rate, but disintegration is a wet process, spurred by positive feedbacks, and once well underway it can be explosively rapid.” Zwally replied “Well, you have been crucified before, and March is the right time of year for that, but I would delete ‘to Hell’ and ‘explosively”’. I thought immediately of the fellow who went over Niagara Falls without a barrel. Would not he consider that a joy ride, compared to slipping on the banks of the rushing melt-water stream, clawing desperately in the freezing water before being hurtled down the moulin more than a kilometer, and eventually being crushed by the giant grinding glacier? “A slippery slope to Hell” did not seem like an exaggeration. On the other hand, I was using “slippery slope” mainly as a metaphor for the danger posed by global warming. So I changed “Hell” to “disaster.” What about “explosively”? Consider the situation during past ice sheet disintegrations. In melt-water pulse 1A, about 14,000 years ago, sea level rose about 20 m in approximately 400 years (Kienast et al., 2003). That is an average of 1 m of sea level rise every 20 years. The nature of glacier disintegration required for delivery of that much water from the ice sheets to the ocean would be spectacular (5 cm of sea level, the mean annual change, is about 15,000 cubic kilometers of water). “Explosively” would be an apt description, if future ice sheet disintegration were to occur at a substantial fraction of the melt-water pulse 1A rate. Are we on a slippery slope now? Can human-made global warming cause ice sheet melting measured in meters of sea level rise, not centimeters, and can this occur in centuries, not millennia? Can the very inertia of the ice sheets, which protects us from rapid sea level change now, become our bete noire?
  4. Overland, James, et al. “The Arctic and Antarctic: Two faces of climate change.” Eos, Transactions American Geophysical Union 89.19 (2008): 177-178.  Although both the Arctic and Antarctic are subject to a similar annual cycle of solar radiation and the same increasing greenhouse gas concentrations, over the previous two decades the two regions have experienced dramatically different changes in sea ice extent, temperature, and other climatic indicators. While these differing responses suggest a paradox, they are largely consistent with known climate dynamics. This conclusion was drawn by scientists participating in the Second Workshop on Recent High Latitude Climate Change, in Seattle, Wash., in October 2007, against the dramatic backdrop of major Arctic sea ice reductions 1 month earlier [World Climate Research Programme, 2007].
  5. Aronson, Richard B. etal. “Anthropogenic impacts on marine ecosystems in Antarctica.” Annals of the New York Academy of Sciences 1223.1 (2011): 82-107. Antarctica is the most isolated continent on Earth, but it has not escaped the negative impacts of human activity. The unique marine ecosystems of Antarctica and their endemic faunas are affected on local and regional scales by overharvesting, pollution, and the introduction of alien species. Global climate change is also having deleterious impacts: rising sea temperatures and ocean acidification already threaten benthic and pelagic food webs. The Antarctic Treaty System can address local‐ to regional‐scale impacts, but it does not have purview over the global problems that impinge on Antarctica, such as emissions of greenhouse gases. Failure to address human impacts simultaneously at all scales will lead to the degradation of Antarctic marine ecosystems and the homogenization of their composition, structure, and processes with marine ecosystems elsewhere.
  6. Agee, Ernest, Andrea Orton, and John Rogers. “CO2 snow deposition in Antarctica to curtail anthropogenic global warming.” Journal of applied meteorology and climatology 52.2 (2013): 281-288.  A scientific plan is presented that proposes the construction of carbon dioxide (CO2) deposition plants in the Antarctic for removing CO2 gas from Earth’s atmosphere. The Antarctic continent offers the best environment on Earth for CO2 deposition at 1 bar of pressure and temperatures closest to that required for terrestrial air CO2 “snow” deposition—133 K. This plan consists of several components, including 1) air chemistry and CO2 snow deposition, 2) the deposition plant and a closed-loop liquid nitrogen refrigeration cycle, 3) the mass storage landfill, 4) power plant requirements, 5) prevention of dry ice sublimation, and 6) disposal (or use) of thermal waste. Calculations demonstrate that this project is worthy of consideration, whereby 446 deposition plants supported by sixteen 1200-MW wind farms can remove 1 billion tons (1012 kg) of carbon (1 GtC) annually (a reduction of 0.5 ppmv), which can be stored in an equivalent “landfill” volume of 2 km × 2 km × 160 m (insulated to prevent dry ice sublimation). The individual deposition plant, with a 100 m × 100 m × 100 m refrigeration chamber, would produce approximately 0.4 m of CO2 snow per day. The solid CO2 would be excavated into a 380 m × 380 m × 10 m insulated landfill, which would allow 1 yr of storage amounting to 2.24 × 10−3 GtC. Demonstrated success of a prototype system in the Antarctic would be followed by a complete installation of all 446 plants for CO2 snow deposition and storage (amounting to 1 billion tons annually), with wind farms positioned in favorable coastal regions with katabatic wind currents.
  7. Ludescher, Josef, et al. “Long-term persistence enhances uncertainty about anthropogenic warming of Antarctica.” Climate dynamics 46.1-2 (2016): 263-271.  Previous estimates of the strength and the uncertainty of the observed Antarctic temperature trends assumed that the natural annual temperature fluctuations can be represented by an auto-regressive process of first order [AR(1)]. Here we find that this hypothesis is inadequate. We consider the longest observational temperature records in Antarctica and show that their variability is better represented by a long-term persistent process that has a propensity of large and enduring natural excursions from the mean. As a consequence, the statistical significance of the recent (presumably anthropogenic) Antarctic warming trend is lower than hitherto reported, while the uncertainty about its magnitude is enhanced. Indeed, all records except for one (Faraday/Vernadsky) fail to show a significant trend. When increasing the signal-to-noise ratio by considering appropriate averages of the local temperature series, we find that the warming trend is still not significant in East Antarctica and the Antarctic Peninsula. In West Antarctica, however, the significance of the trend is above 97.4%97.4%, and its magnitude is between 0.08 and 0.96 °C per decade. We argue that the persistent temperature fluctuations not only have a larger impact on regional warming uncertainties than previously thought but also may provide a potential mechanism for understanding the transient weakening (“hiatus”) of the regional and global temperature trends.
  8. Previdi, Michael, and Lorenzo M. Polvani. “Anthropogenic impact on Antarctic surface mass balance, currently masked by natural variability, to emerge by mid-century.” Environmental Research Letters 11.9 (2016): 094001Global and regional climate models robustly simulate increases in Antarctic surface mass balance (SMB) during the twentieth and twenty-first centuries in response to anthropogenic global warming. Despite these robust model projections, however, observations indicate that there has been no significant change in Antarctic SMB in recent decades. We show that this apparent discrepancy between models and observations can be explained by the fact that the anthropogenic climate change signal during the second half of the twentieth century is small compared to the noise associated with natural climate variability. Using an ensemble of 35 global coupled climate models to separate signal and noise, we find that the forced SMB increase due to global warming in recent decades is unlikely to be detectable as a result of large natural SMB variability. However, our analysis reveals that the anthropogenic impact on Antarctic SMB is very likely to emerge from natural variability by the middle of the current century, thus mitigating future increases in global sea level.

 

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THIS POST IS A CRITICAL EVALUATION OF AN IRISH PUBLIC BROADCAST SERVICE VIDEO ABOUT THE IMPACT OF AGW ON THE ARCTIC [LINK] . IT IS PRESENTED IN TWO PARTS. PART-1 IS A TRANSCRIPT OF THE YOUTUBE VIDEO LECTURE. PART-2 IS A CRITICAL EVALUATION OF THE CLAIMS MADE IN THE LECTURE. 

 

 

PART-1: TRANSCRIPT OF THE YOUTUBE VIDEO  LECTURE

  1. The Arctic is warming twice as fast as the rest of the world. So Greenland is on the front line when it comes to observing climate change. Thirteen years ago we traveled here to Disko Bay, home to the tallest icebergs in the world. Now we have returned to find out what’s happened to this incredible landscape. The first impression is still one of wonder. This UNESCO World Heritage site is home to the Yakob Sound Glacier. As it melts, it releases more fresh water into the sea, more than any glacier in the Northern Hemisphere. bandicam 2020-02-07 08-30-44-545
  2. The first thing we noticed is how the town of Ilulissat, Greenland has experienced a tourist boom. The attraction is clear but the underlying reason was unnerving. The tourists are here to see the ice before it all melts away. Back in 2006 it was already clear that dramatic change had happened within people’s lifetimes. Native speaks: “Old people always talks about when they were kids, the ice was much bigger and more dangerous, dangerous in this way that they are ready to break off or break in two. But now they are smaller and more smooth on the surface”.bandicam 2020-02-07 08-53-26-619
  3. Back then most of the icebergs were pristine, but in 2019 a startling change as the glacier retreated further inland. Iceberg after iceberg was now covered in dirt. All around Disko Bay we saw icebergs studded in grit, stones, and sand. Native: “We see more dirty icebergs because they are touching the ?clumbear? in the mountains. That’s why we see a lot of dirty icebergs”. bandicam 2020-02-07 09-18-02-417
  4. We know that where the system is chaotic rather than linear and glacial retreat isn’t straightforward either. Sometimes Yakob Sound retreats rapidly by as much as 17 km in a single year. And sometimes it stalls for a decade or more; but the trajectory over the century and a half is clear. In the past 3 years Yakob Sound has not just stalled but even gained some mass. bandicam 2020-02-07 09-26-23-094
  5. However, scientists can explain this and it is not good news. Scientists explain the science of  anomalous Yakob Sound melt/gain events: Scientist#1: “Ten years ago the glacier was influenced a lot more by the warming water in the fjord than it is today. And now the water is not interacting with the glacier as much as it was before and that’s why it can build up more ice“. Scientist#2: The rate of melting of these icebergs and the glacier will vary. However, the overall trend is absolutely clear. So too are the consequences. bandicam 2020-02-07 09-35-48-039
  6. We know that Yakob Sound is already contributing to the rise of sea levels. We know that climate change is triggering more frequent storm surges. Increased flooding is inevitable. What begins here in an isolated Arctic wilderness, a place that seems like a world away, is closer to home than we think. bandicam 2020-02-07 10-48-35-247

 

 

 

PART-2: CRITICAL COMMENTARY ON THE  LECTURE

  1. CLAIM: The Arctic is warming twice as fast as the rest of the world. So Greenland is on the front line when it comes to observing climate change. RESPONSE: When dramatic glacial melt events occur and when September minimum sea ice appears to be ready for that coveted ice free Arctic condition, the Arctic is on the front line when it comes observing climate change. When there is more than one Indian Ocean cyclone in any given year ravaging poor African countries, then the Indian Ocean is on the front line when it comes to observing climate change. When there are particularly destructive wildfires in California with loss of life and property, then California is on the front line when it comes to observing climate change. When there are particularly dramatic bushfires in Australia then Australia is on the front line when it comes to observing climate change. When there is a particularly strong Hurricane in the USA or the Caribbean, then the North Atlantic tropical cyclone basin is on the front line when it comes to observing climate change. When there is a dramatic ice melt event in Antarctica then Antarctica is on the front line when it comes to observing climate change even if it turns out that the ice melt event was triggered by volcanic activity under the ice. All such attributions and their use in pushing for climate action are attributions of convenience driven by confirmation bias and the activism needs of the climate action agenda against fossil fuels.   
  2. CLAIM: As the Yakob Sound Glacier melts, it releases more fresh water into the sea, more than any glacier in the Northern Hemisphere. RESPONSE: So what? When glaciers melt they release freshwater into the sea, some glaciers more than others and these things tend to happen in interglacials particularly so during warming cycles of interglacials that are known to undergo warming and cooling cycles at millennial and centennial time scales [LINK]
  3. CLAIM: the town of Ilulissat, Greenland has experienced a tourist boom. The attraction is clear but the underlying reason was unnerving. The tourists are here to see the ice before it all melts away.  RESPONSE: Tourism to Ilulissat is promoted in this way. The tourists are there not because their scientific investigation of the melt data convinced them that they better see the ice before it’s all gone. They are there because that is how the tourism business in Ilulissat is advertised – come and see the ice before it is all gone. That a tourism business is promoted in this way is neither science nor any kind of empirical evidence that the ice in Ilulissat will soon be completely gone and that this is your last chance to see it. It’s business.
  4. CLAIM: Back in 2006 it was already clear that dramatic change had happened within people’s lifetimes. Native speaks: “Old people always talks about when they were kids, the ice was much bigger and more dangerous, dangerous in this way that they are ready to break off or break in two. But now they are smaller and more smooth on the surface”.  RESPONSE: It is true that there was a singular and dramatic melt event in 2006  when it seemed that Greenland was melting at a rate of 20 cubic kilometers per month. However, forecasts based on that isolated and singular event turned out to be wrong. In any case, if when the old people were kids they saw that the ice was dangerous and ready to break off, why is it so surprising to their children that the ice did break off?
  5. CLAIM: Back when the old timers were kids, most of the icebergs were pristine, but in 2019 there was a startling change as the glacier retreated further inland. Iceberg after iceberg was now covered in dirt. All around Disko Bay we saw icebergs studded in grit, stones, and sand. Native: “We see more dirty icebergs because they are touching the ?clumbear? in the mountains. That’s why we see a lot of dirty icebergs”. RESPONSE: Yes, this is what happens when glaciers retreat and what had happened when the glacier had retreated in prior melt events but it seems unlikely that rational people would give up fossil fuels in a climate action plan just to clean up the dirty icebergs especially since these are historical events in a glacier that has been advancing in recent years.
  6. CLAIM: We know that where the system is chaotic rather than linear and glacial retreat isn’t straightforward. Sometimes Yakob Sound retreats rapidly by as much as 17 km in a single year. And sometimes it stalls for a decade or more; but the trajectory over the century and a half is clear. In the past 3 years Yakob Sound has not just stalled but even gained some mass. RESPONSE:  If the system is chaotic the trajectory can’t be clear. If we hunt and choose we can surely find periods of recession just as we can find periods of advance – as for example in recent years –  but a rational and unbiased evaluation free from confirmation bias would not find a “clear trajectory” of a receding Yakob Sound glacier caused by fossil fuel driven AGW climate change.
  7. CLAIM: Scientists can explain why the proposed AGW driven melt of the Yakob Sound glacier is so complicated with periods when it recedes, periods when it advances and periods when it does neither. Scientist#1: “Ten years ago the glacier was influenced a lot more by the warming water in the fjord than it is today. And now the water is not interacting with the glacier as much as it was before and that’s why it can build up more ice“. RESPONSE: The data used to construct a theory can’t be used to test that theory. This kind of thing is called “circular reasoning” and down in Texas it’s called the “Texas Sharpshooter Fallacy” – that is shoot first and draw the target circle later around the holes where your bullets had hit. texas-1
  8. CLAIM: Scientists can explain why the proposed AGW driven melt of the Yakob Sound glacier is so complicated with periods when it recedes, periods when it advances and periods when it does neither. Scientist#2: The rate of melting of these icebergs and the glacier will vary. However, the overall trend is absolutely clear. So too are the consequences. RESPONSE:  It’s not just that the rate of melt varies but what we also see are alternating periods of melt and gain and it is not clear how that process is driven by AGW climate change and its steady long term upward trend in surface air temperature. There are probably other variables to be considered that have not been presented in this video. In related posts it is shown that the Arctic is geologically active and it may be necessary to include known ocean floor geological activity to gain a better understanding of ice melt phenomena in the Arctic region. [LINK] [LINK] [LINK] .
  9. CLAIM: We know that Yakob Sound is already contributing to the rise of sea levels. We know that climate change is triggering more frequent storm surges. Increased flooding is inevitable. What begins here in an isolated Arctic wilderness, a place that seems like a world away, is closer to home than we think. RESPONSE: Maybe it is inevitable but the repeated and comical failure of forecasts of such events and their dire consequences does not imply that the science of sea level rise is well understood by climate science [LINK] . Of late the sea level rise horror has been re-invented in terms of larger uncertainties in the elevation of “low lying areas”. At current sea level rise forecasts, it was projected that 110 million people will be affected by coastal high tide flooding events by the year 2100 but new improved DEM data for coastal land elevation shows that they are not as high as we had thought and so the number of people affected by high tide flood events at the same rate of sea level rise will be higher, maybe 190 million or somewhere between 140 and 240 million. A problem with that assessment is that the large uncertainty in coastal land elevation data may mean that we don’t really know what the coastal land elevation is exactly. [LINK]

 

Background: The 2019–20 Australian bushfire season began with uncontrolled fires in June 2019. As of January 15 2020, hundreds of fires are burning, mainly in the southeast of the continent with 18.6 million hectares consumed and 6,000 homes and structures destroyed. One billion animals have been killed and some endangered species may be driven to extinction. The cost of these fires is expected to exceed that of the 2009 fires. NASA estimates that 306 million tonnes of CO2 was emitted. The role of ENSO, IOD, and SAM (Southern Annular Mode] in these fires is acknowledged but AGW is claimed as the cause because it is thought that AGW climate change has intensified these climatology cycles and made their impact more severe. It is therefore claimed that the fires are ultimately attributable to fossil fuel emissions of the industrial economy. 

[LINK TO POST ON THE BUSHFIRES]

 

THIS POST PROVIDES A RELEVANT BIBLIOGRAPHY FOR RESEARCHERS ON THIS TOPIC. SOME VERY RECENT PAPERS ARE MISSING AND WILL BE ADDED ASAP. 

 

[HOME PAGE OF THIS SITE]

 

 

AUSTRALIA: ENSO, IOD, SAM BIBLIOGRAPHY

  1. Ashok, Karumuri, Zhaoyong Guan, and Toshio Yamagata. “Influence of the Indian Ocean Dipole on the Australian winter rainfall.” Geophysical Research Letters 30.15 (2003).  [FULL TEXT]  Using an atmospheric general circulation model and observed datasets of sea surface temperature and rainfall, we studied the influence of the Indian Ocean Dipole (IOD) on the Australian winter rainfall. The IOD has significant negative partial correlations with rainfall over the western and southern regions of Australia. These negative partial correlations extend south‐eastward from Indonesia all the way to south east Australia. Our atmospheric general circulation model sensitivity experiments indicate that cold sea surface temperature anomalies prevailing west of the Indonesian archipelago during the positive IOD events introduce an anomalous anticyclonic circulation at lower levels over the eastern tropical and subtropical Indian Ocean, and over much of the Australian continent. It is also apparent that the response of the atmosphere to the IOD in this region is baroclinic, causing anomalous subsidence and anomalous reduction in the rainfall over the affected regions of Australia.
  2. England, Matthew H., Caroline C. Ummenhofer, and Agus Santoso. “Interannual rainfall extremes over southwest Western Australia linked to Indian Ocean climate variability.” Journal of Climate 19.10 (2006): 1948-1969[FULL TEXT] Interannual rainfall extremes over southwest Western Australia (SWWA) are examined using observations, reanalysis data, and a long-term natural integration of the global coupled climate system. The authors reveal a characteristic dipole pattern of Indian Ocean sea surface temperature (SST) anomalies during extreme rainfall years, remarkably consistent between the reanalysis fields and the coupled climate model but different from most previous definitions of SST dipoles in the region. In particular, the dipole exhibits peak amplitudes in the eastern Indian Ocean adjacent to the west coast of Australia. During dry years, anomalously cool waters appear in the tropical/subtropical eastern Indian Ocean, adjacent to a region of unusually warm water in the subtropics off SWWA. This dipole of anomalous SST seesaws in sign between dry and wet years and appears to occur in phase with a large-scale reorganization of winds over the tropical/subtropical Indian Ocean. The wind field alters SST via anomalous Ekman transport in the tropical Indian Ocean and via anomalous air–sea heat fluxes in the subtropics. The winds also change the large-scale advection of moisture onto the SWWA coast. At the basin scale, the anomalous wind field can be interpreted as an acceleration (deceleration) of the Indian Ocean climatological mean anticyclone during dry (wet) years. In addition, dry (wet) years see a strengthening (weakening) and coinciding southward (northward) shift of the subpolar westerlies, which results in a similar southward (northward) shift of the rain-bearing fronts associated with the subpolar front. A link is also noted between extreme rainfall years and the Indian Ocean Dipole (IOD). Namely, in some years the IOD acts to reinforce the eastern tropical pole of SST described above, and to strengthen wind anomalies along the northern flank of the Indian Ocean anticyclone. In this manner, both tropical and extratropical processes in the Indian Ocean generate SST and wind anomalies off SWWA, which lead to moisture transport and rainfall extremes in the region. An analysis of the seasonal evolution of the climate extremes reveals a progressive amplification of anomalies in SST and atmospheric circulation toward a wintertime maximum, coinciding with the season of highest SWWA rainfall. The anomalies in SST can appear as early as the summertime months, however, which may have important implications for predictability of SWWA rainfall extremes.
  3. Gillett, N. Pꎬ, T. Dꎬ Kell, and P. D. Jones. “Regional climate impacts of the Southern Annular Mode.” Geophysical Research Letters 33.23 (2006)[FULL TEXT]  Previous work on the influence of the Southern Annular Mode (SAM) on surface climate has focused mainly on individual countries. In this study we use station observations of temperature and rainfall to identify the influence of the SAM on land regions over the whole of the Southern Hemisphere. We demonstrate that the positive phase of the SAM is associated with a significant cooling over Antarctica and much of Australia, and a significant warming over the Antarctic Peninsula, Argentina, Tasmania and the south of New Zealand. The positive phase of the SAM is also associated with anomalously dry conditions over southern South America, New Zealand and Tasmania, due to the southward shift of the stormtrack; and to anomalously wet conditions over much of Australia and South Africa. These influences on populated regions of the Southern Hemisphere may have implications for weather and seasonal forecasting, and for future climate change.
  4. A review of recent climate variability and climate change in southeastern Australia, Bradley F. Murphy Bertrand Timbal, First published:15 October 2007 https://doi.org/10.1002/joc.1627 Southeastern Australia (SEA) has suffered from 10 years of low rainfall from 1997 to 2006. A protracted dry spell of this severity has been recorded once before during the 20th century, but current drought conditions are exacerbated by increasing temperatures. Impacts of this dry decade are wide‐ranging, so a major research effort is being directed to better understand the region’s recent climate, its variability and climate change. This review summarizes the conditions of these 10 years and the main mechanisms that affect the climate.Most of the rainfall decline (61%) has occurred in autumn (March–May). Daily maximum temperatures are rising, as are minimum temperatures, except for cooler nights in autumn in the southwest of SEA closely related to lower rainfall. A similar rainfall decline occurred in the southwest of western Australia around 1970 that has many common features with the SEA decline. SEA rainfall is produced by mid‐latitude storms and fronts, interactions with the tropics through continental‐scale cloudbands and cut‐off lows. El Niño‐Southern Oscillation impacts on SEA rainfall, as does the Indian Ocean, but neither has a direct influence in autumn. Trends have been found in both hemispheric (the southern annular mode) and local (sub‐tropical ridge) circulation features that may have played a role in reducing the number and impact of mid‐latitude systems around SEA, and thus reducing rainfall. The role of many of these mechanisms needs to be clarified, but there is likely to be an influence of enhanced greenhouse gas concentrations on SEA climate, at least on temperature. Copyright © 2007 Royal Meteorological Society
  5. Abram, Nerilie J., et al. “Seasonal characteristics of the Indian Ocean Dipole during the Holocene epoch.” Nature 445.7125 (2007): 299-302. The Indian Ocean Dipole1,2 (IOD)—an oscillatory mode of coupled ocean–atmosphere variability—causes climatic extremes and socio-economic hardship throughout the tropical Indian Ocean region1,2,3,4,5. There is much debate about how the IOD interacts with the El Niño/Southern Oscillation (ENSO) and the Asian monsoon, and recent changes in the historic ENSO–monsoon relationship6 raise the possibility that the properties of the IOD may also be evolving. Improving our understanding of IOD events and their climatic impacts thus requires the development of records defining IOD activity in different climatic settings, including prehistoric times when ENSO and the Asian monsoon behaved differently from the present day. Here we use coral geochemical records from the equatorial eastern Indian Ocean to reconstruct surface-ocean cooling and drought during individual IOD events over the past 6,500 years. We find that IOD events during the middle Holocene were characterized by a longer duration of strong surface ocean cooling, together with droughts that peaked later than those expected by El Niño forcing alone. Climate model simulations suggest that this enhanced cooling and drying was the result of strong cross-equatorial winds driven by the strengthened Asian monsoon of the middle Holocene. These IOD–monsoon connections imply that the socioeconomic impacts of projected future changes in Asian monsoon strength may extend throughout Australasia.
  6. Cai, W., T. Cowan, and M. Raupach. “Positive Indian Ocean dipole events precondition southeast Australia bushfires.” Geophysical Research Letters 36.19 (2009). [FULL TEXT] The devastating “Black Saturday” bushfire inferno in the southeast Australian state of Victoria in early February 2009 and the “Ash Wednesday” bushfires in February 1983 were both preceded by a positive Indian Ocean Dipole (pIOD) event. Is there a systematic pIOD linkage beyond these two natural disasters? We show that out of 21 significant bushfires seasons since 1950, 11 were preceded by a pIOD. During Victoria’s wet season, particularly spring, a pIOD contributes to lower rainfall and higher temperatures exacerbating the dry conditions and increasing the fuel load leading into summer. Consequently, pIODs are effective in preconditioning Victoria for bushfires, more so than El Niño events, as seen in the impact on soil moisture on interannual time scales and in multi‐decadal changes since the 1950s. Given that the recent increase in pIOD occurrences is consistent with what is expected from global warming, an increased bushfire risk in the future is likely across southeast Australia.
  7. Cai, W., T. Cowan, and A. Sullivan. “Recent unprecedented skewness towards positive Indian Ocean Dipole occurrences and its impact on Australian rainfall.” Geophysical Research Letters 36.11 (2009)[FULL TEXT]  Is the recent high frequency of positive Indian Ocean Dipole (pIOD) events a consequence of global warming? Using available observations and reanalyses, we show that the pIOD occurrences increase from about four per 30 years early in the 20th century to about 10 over the last 30 years; by contrast, the number of negative Indian Ocean Dipole (nIOD) events decreases from about 10 to two over the same periods, respectively. A skewness measure, defined as the difference in occurrences of pIODs and nIODs, illustrates a systematic trend in this parameter commencing early in the 20th century. After 1950, there are more pIODs than nIODs, with consistent mean circulation changes in the pIOD‐prevalent seasons. Over southeastern Australia (SEA), these changes potentially account for much of the observed austral winter and spring rainfall reduction since 1950. These features are consistent with projected future climate change and hence with what is expected from global warming.
  8. Taschetto, Andrea S., et al. “The contribution of Indian Ocean sea surface temperature anomalies on Australian summer rainfall during El Niño events.” Journal of Climate 24.14 (2011): 3734-3747. [FULL TEXT] This study investigates the impact of Indian Ocean sea surface temperature (SST) anomalies on the atmospheric circulation of the Southern Hemisphere during El Niño events, with a focus on Australian climate. During El Niño episodes, the tropical Indian Ocean exhibits two types of SST response: a uniform “basinwide warming” and a dipole mode—the Indian Ocean dipole (IOD). While the impacts of the IOD on climate have been extensively studied, the effects of the basinwide warming, particularly in the Southern Hemisphere, have received less attention. The interannual basinwide warming response has important implications for Southern Hemisphere atmospheric circulation because 1) it accounts for a greater portion of the Indian Ocean monthly SST variance than the IOD pattern and 2) its maximum amplitude occurs during austral summer to early autumn, when large parts of Australia, South America, and Africa experience their monsoon. Using observations and numerical experiments with an atmospheric general circulation model forced with historical SST from 1949 to 2005 over different tropical domains, the authors show that the basinwide warming leads to a Gill–Matsuno-type response that reinforces the anomalies caused by changes in the Pacific as part of El Niño. In particular, the basinwide warming drives strong subsidence over Australia, prolonging the dry conditions during January–March, when El Niño–related SST starts to decay. In addition to the anomalous circulation in the tropics, the basinwide warming excites a pair of barotropic anomalies in the Indian Ocean extratropics that induces an anomalous anticyclone in the Great Australian Bight.
  9. Werner, Angelika, Angela M. Maharaj, and Neil J. Holbrook. “A new method for extracting the ENSO-independent Indian Ocean Dipole: application to Australian region tropical cyclone counts.” Climate dynamics 38.11-12 (2012): 2503-2511.  We introduce a simple but effective means of removing ENSO-related variations from the Indian Ocean Dipole (IOD) in order to better evaluate the ENSO-independent IOD contribution to Australian climate—specifically here interannual variations in Australian region tropical cyclogensis (TCG) counts. The ENSO time contribution is removed from the Indian Ocean Dipole Mode index (DMI) by first calculating the lagged regression of the DMI on the sea surface temperature anomaly (SSTA) index NINO3.4 to maximum lags of 8 months, and then removing this ENSO portion. The new ENSO-independent time series, DMINOENSO, correlates strongly with the original DMI at r = 0.87 (significant at >99% level). Despite the strength of the correlation between these series, the IOD events classified based on DMINOENSO provide important differences from previously identified IOD events, which are more closely aligned with ENSO phases. IOD event composite maps of SSTAs regressed on DMINOENSO reveal a much greater ENSO-independence than the original DMI-related SSTA pattern. This approach is used to explore relationships between Australian region TCG and IOD from 1968 to 2007. While we show that both the DMI and DMINOENSO have significant hindcast skill (on the 95% level) when used as predictors in a multiple linear regression model for Australian region annual TCG counts, the IOD does not add any significant hindcast skill over an ENSO-only predictor model, based on NINO4. Correlations between the time series of annual TCG count observations and ENSO + IOD model cross-validated hindcasts achieve r = 0.68 (significant at the 99% level).
  10. Pui, Alexander, et al. “Impact of the El Niño–Southern Oscillation, Indian Ocean dipole, and southern annular mode on daily to subdaily rainfall characteristics in east Australia.” Monthly weather review 140.5 (2012): 1665-1682 [FULL TEXT] The relationship between seasonal aggregate rainfall and large-scale climate modes, particularly the El Niño–Southern Oscillation (ENSO), has been the subject of a significant and ongoing research effort. However, relatively little is known about how the character of individual rainfall events varies as a function of each of these climate modes. This study investigates the change in rainfall occurrence, intensity, and storm interevent time at both daily and subdaily time scales in east Australia, as a function of indices for ENSO, the Indian Ocean dipole (IOD), and the southern annular mode (SAM), with a focus on the cool season months. Long-record datasets have been used to sample a large variety of climate events for better statistical significance. Results using both the daily and subdaily rainfall datasets consistently show that it is the occurrence of rainfall events, rather than the average intensity of rainfall during the events, which is most strongly influenced by each of the climate modes. This is shown to be most likely associated with changes to the time between wet spells. Furthermore, it is found that despite the recent attention in the research literature on other climate modes, ENSO remains the leading driver of rainfall variability over east Australia, particularly farther inland during the winter and spring seasons. These results have important implications for how water resources are managed, as well as how the implications of large-scale climate modes are included in rainfall models to best capture interannual and longer-scale variability.
  11. Cai, Wenju, et al. “Projected response of the Indian Ocean Dipole to greenhouse warming.” Nature geoscience 6.12 (2013): 999-1007.  Natural modes of variability centred in the tropics, such as the El Niño/Southern Oscillation and the Indian Ocean Dipole, are a significant source of interannual climate variability across the globe. Future climate warming could alter these modes of variability. For example, with the warming projected for the end of the twenty-first century, the mean climate of the tropical Indian Ocean is expected to change considerably. These changes have the potential to affect the Indian Ocean Dipole, currently characterized by an alternation of anomalous cooling in the eastern tropical Indian Ocean and warming in the west in a positive dipole event, and the reverse pattern for negative events. The amplitude of positive events is generally greater than that of negative events. Mean climate warming in austral spring is expected to lead to stronger easterly winds just south of the Equator, faster warming of sea surface temperatures in the western Indian Ocean compared with the eastern basin, and a shoaling equatorial thermocline. The mean climate conditions that result from these changes more closely resemble a positive dipole state. However, defined relative to the mean state at any given time, the overall frequency of events is not projected to change — but we expect a reduction in the difference in amplitude between positive and negative dipole events.
  12. Abram, Nerilie J., et al. “Evolution of the Southern Annular Mode during the past millennium.” Nature Climate Change 4.7 (2014): 564-569.  The Southern Annular Mode (SAM) is the primary pattern of climate variability in the Southern Hemisphere1,2, influencing latitudinal rainfall distribution and temperatures from the subtropics to Antarctica. The positive summer trend in the SAM over recent decades is widely attributed to stratospheric ozone depletion2; however, the brevity of observational records from Antarctica1—one of the core zones that defines SAM variability—limits our understanding of long-term SAM behaviour. Reconstructed SAM trends before the twentieth century are more prominent than those in radiative-forcing climate experiments and may be associated with a teleconnected response to tropical Pacific climate. Our findings imply that predictions of further greenhouse-driven increases in the SAM over the coming century3 also need to account for the possibility of opposing effects from tropical Pacific climate changes.
  13. Pepler, A., et al. “Indian Ocean Dipole overrides ENSO’s influence on cool season rainfall across the Eastern Seaboard of Australia.” Journal of Climate 27.10 (2014): 3816-3826. [FULL TEXT]  The strong relationship between Eastern Australian winter–spring rainfall and tropical modes of variability such as the El Niño–Southern Oscillation (ENSO) does not extend to the heavily populated coastal strip east of the Great Dividing Range in southeast Australia, where correlations between rainfall and Niño-3.4 are insignificant during June–October. The Indian Ocean dipole (IOD) is found to have a strong influence on zonal wind flow during the winter and spring months, with positive IOD increasing both onshore winds and rainfall over the coastal strip, while decreasing rainfall elsewhere in southeast Australia. The IOD thus opposes the influence of ENSO over the coastal strip, and this is shown to be the primary cause of the breakdown of the ENSO–rainfall relationship in this region.
  14. Sharples, Jason J., et al. “Natural hazards in Australia: extreme bushfire.” Climatic Change 139.1 (2016): 85-99.  Bushfires are one of the most frequent natural hazards experienced in Australia. Fires play an important role in shaping the landscape and its ecological dynamics, but may also have devastating effects that cause human injuries and fatalities, as well as broad-scale environmental damage. While there has been considerable effort to quantify changes in the occurrence of bushfire in Australia, a comprehensive assessment of the most extreme bushfire cases, which exact the greatest economic and environmental impacts, is lacking. In this paper we reflect upon recently developed understanding of bushfire dynamics to consider (i) historical changes in the occurrence of extreme bushfires, and (ii) the potential for increasing frequency in the future under climate change projections. The science of extreme bushfires is still a developing area, thus our conclusions about emerging patterns in their occurrence should be considered tentative. Nonetheless, historical information on noteworthy bushfire events suggests an increased occurrence in recent decades. Based on our best current understanding of how extreme bushfires develop, there is strong potential for them to increase in frequency in the future. As such there is a pressing need for a greater understanding of these powerful and often destructive phenomena.
  15. Mariani, Michela, and Michael‐Shawn Fletcher. “The Southern Annular Mode determines interannual and centennial‐scale fire activity in temperate southwest Tasmania, Australia.” Geophysical Research Letters 43.4 (2016): 1702-1709.  [FULL TEXT] Southern Annular Mode (SAM) is the primary mode of atmospheric variability in the Southern Hemisphere. While it is well established that the current anthropogenic‐driven trend in SAM is responsible for decreased rainfall in southern Australia, its role in driving fire regimes in this region has not been explored. We examined the connection between fire activity and SAM in southwest Tasmania, which lies in the latitudinal band of strongest correlation between SAM and rainfall in the Southern Hemisphere. We reveal that fire activity during a fire season is significantly correlated with the phase of SAM in the preceding year using superposed epoch analysis. We then synthesized new 14 charcoal records from southwest Tasmania spanning the last 1000 years, revealing a tight coupling between fire activity and SAM at centennial timescales, observing a multicentury increase in fire activity over the last 500 years and a spike in fire activity in the 21st century in response to natural and anthropogenic SAM trends.
  16. Dowdy, Andrew J., Michael D. Fromm, and Nicholas McCarthy. “Pyrocumulonimbus lightning and fire ignition on Black Saturday in southeast Australia.” Journal of Geophysical Research: Atmospheres 122.14 (2017): 7342-7354A number of devastating wildfires occurred in southeast Australia on 7 February 2009, colloquially known as Black Saturday. Atmospheric responses to this extreme fire event are investigated here with a focus on convective processes associated with fire activity (i.e., pyroconvection). We examine six different fire complexes on Black Saturday, finding three clearly distinct pyrocumulonimbus storms, the largest of which reached heights of 15 km on that day and generated hundreds of lightning strokes. The first lightning stroke was recorded near the largest fire complex 5 h after fire ignition. One of the pyrocumulonimbus storms was initiated close to midnight due to mesoscale influences, consistent with extreme fire behavior observed at that time for that particular fire. As another example of fire‐atmosphere interactions, a fire that started late on Black Saturday is examined in relation to ignition caused by pyrogenic lightning, with implications for understanding the maximum rate of spread of a wildfire. Results are discussed in relation to another pyrocumulonimbus event associated with the 2003 Canberra fires. Our findings are intended to provide a greater understanding of pyroconvection and fire‐atmosphere feedback processes, as well as help enhance wildfire response capabilities. We also demonstrate the potential for using lightning, radar, and satellite remote sensing in combination with thermodynamic analyses as well as synoptic and mesoscale dynamics to provide enhanced real‐time guidance for dangerous fire conditions associated with pyroconvection, as well as for the risk of new fire ignitions from pyrogenic lightning.

 

 

 

AUSTRALIA PALEOCLIMATE BIBLIOGRAPHY

  1. Heusser, Linda E., and Guus Van de Geer. “Direct correlation of terrestrial and marine paleoclimatic records from four glacial-interglacial cycles—DSDP Site 594 Southwest Pacific.” Quaternary Science Reviews 13.3 (1994): 273-282.  Over the last ∼350 ka, changes in the composition of vegetation on New Zealand (inferred from pollen analysis of the upper 40 m of DSDP Site 594 at ∼2.4 ka sample intervals) reflect regional climatic variations which appear synchronous with implied variations in glacier fluctuation and in global climatostratigraphy described from sedimentary and oxygen isotope records from the same samples (Nelson et al., 1985). Pollen assemblages from Isotope Stages 1, 5e, 7a, 7b and 9 are distinguished by conifer and broadleaf forest taxa which vary in composition between the last four interglacials, suggesting significant differences in precipitation, temperature, and/or migration rates. Glacial pollen assemblages, which imply the expansion of herbland and decline in forest components, show less variation and generally indicate comparatively cool conditions on the east coast of South Island. Interstadial vegetation is composed of a mosaic of shrubland/herbland vegetation. The close correspondence between variations in the amplitude and timing of these continuous records of forest development in the changing vegetation of South Island, New Zealand, and oxygen isotope climatostratigraphy supports previous suggestions that Late Quaternary southern and northern hemisphere climatic fluctuations were essentially synchronous.
  2. Joussaume, S., and K. E. Taylor. “Status of the paleoclimate modeling intercomparison project (PMIP).” World Meteorological Organization-Publications-WMO TD (1995): 425-430[FULL TEXT] Partly inspired by AMIP, the Paleoclimate Modeling Intercomparison Project (PMIP) was initiated in order to coordinate and encourage the systematic study of atmospheric general circulation models (AGCMs) and to assess their ability to simulate large changes of climate such as those that occurred in the distant past. Project goals include identifying common responses of AGCMs to imposed paleoclimate “boundary conditions,” understanding the differences in model responses, comparing model results with paleoclimate data, and providing AGCM results for use in helping in the analysis and interpretation of paleoclimate data. PMIP is initially focussing on the mid-Holocene (6,000 years Before Present) and the last glacial maximum (21,000 yr BP) because climatic conditions were remarkably different at those times and because relatively large amounts of paleoclimate data exist for these periods. The major “forcing” factors are also relatively well known at these times. Some of the paleoclimate features simulated by models in previous studies seem consistent with paleoclimatic data, but others do not. One of the goals of PMIP is to determine which results are model-dependent. The PMIP experiments are limited to studying the equilibrium response of the atmosphere (and such surface characteristics as snow cover) to changes in boundary conditions (e.g., insolation, ice-sheet distribution, CO2 concentration, etc.) PMIP has been endorsed by both IGBP/PAGES and WCRP/WGNE, and more than fifteen modeling groups are participating. Several of these groups have completed one or more of the PMIP simulations. Model output will be archived at the Program for Climate Model Diagnosis and Intercomparison (PCMDI) in a structure similar to the AMIP standard output. A workshop involving a representative of each of the PMIP modeling groups is planned for the Fall of 1995 in which results from the PMIP simulations will be shared and subprojects focussing on specific issues will be formed.
  3. Baldini, J. U. L., F. McDermott, and I. J. Fairchild. “Spatial variability in cave drip water hydrochemistry: Implications for stalagmite paleoclimate records.” Chemical Geology 235.3-4 (2006): 390-404.  The identification of vadose zone hydrological pathways that most accurately transmit climate signals through karst aquifers to stalagmites is critical for accurately interpreting climate proxies contained within individual stalagmites. A three-year cave drip hydrochemical study across a spectrum of drip types in Crag Cave, SW Ireland, reveals substantial variability in drip hydrochemical behaviour. Stalagmites fed by very slow drips (< 0.1 ml/min) may best retain information regarding decadal- through millennial-scale climate because the drip sites’ diffuse recharge minimizes interferences to the long-term pattern produced by isolated meteorological events. Additionally, hydrological routing shifts did not influence these very slow drips. Intermediate flow regimes (0.1–2 ml/min) are apparently most sensitive to water excess, and may best preserve a paleoseasonality signal because of a combination of rapid stalagmite growth, seasonally responsive drip rates, and minimal interferences from stochastic processes within the aquifer. Stochastic drip-rate variability existed at several high-discharge (> 2 ml/min) sites, apparently unconnected with local meteorological events. Water from these drips was typically undersaturated with respect to calcite, and thus did not result in calcite deposition. Data presented here suggest that drips in this flow regime also experience flow re-routing and blocking, and that any stalagmites developed under such drips are unsuitable as mid- to high-resolution paleoclimate proxies. Most drip sites demonstrated seasonal [Ca2+] and [Mg2+] variability that was probably linked to water excess. Prior calcite precipitation along the flowpath affected the chemistry of slowly dripping sites, while dilution predominantly controlled the water chemistry of the more rapidly dripping sites. This research underscores the importance of understanding drip hydrology prior to selecting stalagmites for paleoclimate analysis and before interpreting any subsequent proxy data.
  4. Verdon, Danielle C., and Stewart W. Franks. “Long‐term behaviour of ENSO: Interactions with the PDO over the past 400 years inferred from paleoclimate records.” Geophysical Research Letters 33.6 (2006).  This study uses proxy climate records derived from paleoclimate data to investigate the long‐term behaviour of the Pacific Decadal Oscillation (PDO) and the El Niño Southern Oscillation (ENSO). During the past 400 years, climate shifts associated with changes in the PDO are shown to have occurred with a similar frequency to those documented in the 20th Century. Importantly, phase changes in the PDO have a propensity to coincide with changes in the relative frequency of ENSO events, where the positive phase of the PDO is associated with an enhanced frequency of El Niño events, while the negative phase is shown to be more favourable for the development of La Niña events.
  5. Verdon**, D., and S. W. Franks. “Long-term drought risk assessment in the Lachlan River Valley–A paleoclimate perspective.” Australasian Journal of Water Resources 11.2 (2007): 145-152.  The frequency and severity of droughts during the past two decades in eastern Australia have caused water resource managers to question the suitability of current drought management practices. For example, water accounting schemes in NSW (and elsewhere) use an estimate of the “worst drought in 100 years” for resource assessment, which is based solely on the instrumental record. However, inflows during the most recent drought (2002–2007) were lower than those recorded in the last 100 years for some of the catchments in NSW. This resulted in an overestimate of expected inflows and critically low storage volumes (ie. failure of the system). It is clear that hydrological drought risk would be better assessed by extending the records beyond the single 100 year instrumental record, so as to capture a larger spectrum of climatic variability. Incorporating paleoclimate information on the major climate drivers for the region may provide the critical insight required to achieve this goal. In this paper, proxy climate records derived from paleoclimate data are used to investigate the long-term behaviour of the Interdecadal Pacific Oscillation (IPO) and the El Niño/Southern Oscillation (ENSO). This information is then used to develop a stochastic framework for generating rainfall replicates to be used in assessing long-term hydrologic drought risk for water resource management in NSW. Importantly, the rainfall replicates demonstrate that this region may have experienced meteorological droughts of longer duration than has been recorded by the instrumental record. This result highlights the possibility that current management practices may fail to meet needs in the future, if history were to be repeated.
  6. Woodhead, Jon, et al. “Speleothem climate records from deep time? Exploring the potential with an example from the Permian.” Geology 38.5 (2010): 455-458.  Speleothems are well-proven archives of terrestrial climate variation, recording mean temperature, rainfall, and surface vegetation data at subannual to millennial resolution. They also form within the generally stable environment of caves, and thus may remain remarkably well preserved for many millions of years and, most important, can be dated radiometrically to provide robust chronologies that do not rely on orbital tuning, ice-flow modeling, or estimates of sediment deposition rates. The recent adaptation of the U-Pb dating technique to speleothems has greatly extended their potential as paleoclimate recorders back into the more distant geological past, well beyond the ∼500 k.y. limit previously imposed by U-series techniques, but the opportunities presented by these new methods have yet to be fully explored. As an extreme example, here we report on samples recovered from Permian cave fills, the oldest radiometrically dated speleothems so far documented. Using state of the art analytical techniques it is possible to determine not only their age and state of preservation, but also to extract apparently nearly pristine climate proxy data. Armed with these methods, it now seems reasonable to apply the lessons learned from more recent speleothems to ancient materials, wherever they can be found, and of whatever age, to generate snapshots of paleoclimate that can be used to greatly refine the records preserved within the sediments and fossils of the time.
  7. Lough, Janice M. “Climate records from corals.” Wiley interdisciplinary reviews: climate change 1.3 (2010): 318-331.  Understanding the nature and causes of climate variability and change in the tropical oceans—the heat engine of the global climate system—is limited by the relatively short length of instrumental records. Certain massive reef‐building corals contain a wealth of historical proxy climate and environmental information locked in their calcium carbonate skeletons. This information is available from living corals that can be up to several hundred years old and from fossil corals, often well preserved after death, for well‐dated windows of the more distant past. Continuous, high‐resolution (annual to seasonal) information from such corals is provided by a range of measures that include growth characteristics which can document coral responses to unusual environmental conditions and various geochemical tracers whose incorporation into the skeleton is mediated by ambient seawater characteristics. The stable oxygen isotope ratio, δ18O, has been the most commonly measured coral environmental tracer and, although reflecting both sea surface temperature and seawater salinity, long records of this variable are providing new insights into interannual (e.g., El Niño‐Southern Oscillation), decadal, and longer time‐scale variability in the tropical oceans—information not accessible from the instrumental records—which complements other sources of high‐resolution proxy climate information (e.g., tree rings, ice cores, documentary records). The contribution of proxy climate records in corals to the global picture of past climates is being enhanced through efforts to reduce the various sources of uncertainty that can confound the interpretation of any source of proxy climate information. Copyright © 2010 John Wiley & Sons, Ltd.
  8. Phipps, Steven J., et al. “Paleoclimate data–model comparison and the role of climate forcings over the past 1500 years.” Journal of Climate 26.18 (2013): 6915-6936[FULL TEXT] The past 1500 years provide a valuable opportunity to study the response of the climate system to external forcings. However, the integration of paleoclimate proxies with climate modeling is critical to improving the understanding of climate dynamics. In this paper, a climate system model and proxy records are therefore used to study the role of natural and anthropogenic forcings in driving the global climate. The inverse and forward approaches to paleoclimate data–model comparison are applied, and sources of uncertainty are identified and discussed. In the first of two case studies, the climate model simulations are compared with multiproxy temperature reconstructions. Robust solar and volcanic signals are detected in Southern Hemisphere temperatures, with a possible volcanic signal detected in the Northern Hemisphere. The anthropogenic signal dominates during the industrial period. It is also found that seasonal and geographical biases may cause multiproxy reconstructions to overestimate the magnitude of the long-term preindustrial cooling trend. In the second case study, the model simulations are compared with a coral δ18O record from the central Pacific Ocean. It is found that greenhouse gases, solar irradiance, and volcanic eruptions all influence the mean state of the central Pacific, but there is no evidence that natural or anthropogenic forcings have any systematic impact on El Niño–Southern Oscillation. The proxy climate relationship is found to change over time, challenging the assumption of stationarity that underlies the interpretation of paleoclimate proxies. These case studies demonstrate the value of paleoclimate data–model comparison but also highlight the limitations of current techniques and demonstrate the need to develop alternative approaches.
  9. Ho, Michelle, Anthony S. Kiem, and Danielle C. Verdon‐Kidd. “A paleoclimate rainfall reconstruction in the Murray‐Darling Basin (MDB), Australia: 2. Assessing hydroclimatic risk using paleoclimate records of wet and dry epochs.” Water Resources Research 51.10 (2015): 8380-8396.  [FULL TEXT] .  Estimates of hydrological risk are crucial to enable adequate planning and preparation for extreme events. However, the accurate estimation of hydrological risk is hampered by relatively short instrumental records in many parts of the world. Information derived from climate‐sensitive paleoclimate proxies provide an opportunity to resolve hydroclimatic variability, but many regions, such as Australia’s Murray‐Darling Basin (MDB), currently lack the suitable in situ proxies necessary to do this. Here new MDB rainfall reconstructions are presented based on a novel method using paleoclimate rainfall proxies in the Australasian region spanning from 749 B.C.E. to 1980 C.E. Our results emphasize the need to develop additional reconstructions and, with the companion paper, demonstrate how this information can be used to benefit water resource management. This study shows that prior to the twentieth century, both dry and wet epochs have persisted for longer periods than observed in the instrumental record—with the probability of both dry and wet periods exceeding a decade at least 10 times more likely prior to 1883 than suggested by the instrumental records. Some reconstructed rainfalls exceeded the instrumental range (i.e., drier dry epochs and wetter wet spells) despite a systematic underestimation of extremes due to a combination of proxy quality and model bias. Importantly, the results demonstrate that the instrumental record does not cover the full range of hydroclimatic variability possible in the MDB. Therefore, hydroclimatic risk assessments based on the instrumental record likely underestimate, or at least misinterpret, the frequency, duration, and magnitude of wet and dry epochs.

 

 

AGW AND WILDFIRES BIBLIOGRAPHY

  1. Goldammer, Johann Georg, and Colin Price. “Potential impacts of climate change on fire regimes in the tropics based on MAGICC and a GISS GCM-derived lightning model.” Climatic Change 39.2-3 (1998): 273-296.  Investigations of the ecological, atmospheric chemical, and climatic impacts of contemporary fires in tropical vegetation have received increasing attention during the last 10 years. Little is known, however, about the impacts of climate changes on tropical vegetation and wildland fires. This paper summarizes the main known interactions of fire, vegetation, and atmosphere. Examples of predictive models on the impacts of climate change on the boreal and temperate zones are given in order to highlight the possible impacts on the tropical forest and savanna biomes and to demonstrate parameters that need to be involved in this process. Response of tropical vegetation to fire is characterized by degradation towards xerophytic and pyrophytic plant communities dominated by grasses and fire-tolerant tree and bush invaders. The potential impacts of climate change on tropical fire regimes are investigated using a GISS GCM-based lightning and fire model and the Model for the Assessment of Greenhouse Gas-Induced Climate Change (MAGICC).
  2. Bond, W. J., G. F. Midgley, and F. I. Woodward. “The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas.” Global Change Biology 9.7 (2003): 973-982.  The distribution and abundance of trees can be strongly affected by disturbance such as fire. In mixed tree/grass ecosystems, recurrent grass‐fuelled fires can strongly suppress tree saplings and therefore control tree dominance. We propose that changes in atmospheric [CO2] could influence tree cover in such metastable ecosystems by altering their postburn recovery rates relative to flammable herbaceous growth forms such as grasses. Slow sapling recovery rates at low [CO2] would favour the spread of grasses and a reduction of tree cover. To test the possible importance of [CO2]/fire interactions, we first used a Dynamic Global Vegetation Model (DGVM) to simulate biomass in grassy ecosystems in South Africa with and without fire. The results indicate that fire has a major effect under higher rainfall conditions suggesting an important role for fire/[CO2] interactions. We then used a demographic model of the effects of fire on mesic savanna trees to test the importance of grass/tree differences in postburn recovery rates. We adjusted grass and tree growth in the model according to the DGVM output of net primary production at different [CO2] relative to current conditions. The simulations predicted elimination of trees at [CO2] typical of the last glacial period (180 ppm) because tree growth rate is too slow (15 years) to grow to a fire‐proof size of ca. 3 m. Simulated grass growth would produce an adequate fuel load for a burn in only 2 years. Simulations of preindustrial [CO2] (270 ppm) predict occurrence of trees but at low densities. The greatest increase in trees occurs from preindustrial to current [CO2] (360 ppm). The simulations are consistent with palaeo‐records which indicate that trees disappeared from sites that are currently savannas in South Africa in the last glacial. Savanna trees reappeared in the Holocene. There has also been a large increase in trees over the last 50–100 years. We suggest that slow tree recovery after fire, rather than differential photosynthetic efficiencies in C3 and C4 plants, might have been the significant factor in the Late Tertiary spread of flammable grasslands under low [CO2] because open, high light environments would have been a prerequisite for the spread of C4 grasses. Our simulations suggest further that low [CO2] could have been a significant factor in the reduction of trees during glacial times, because of their slower regrowth after disturbance, with fire favouring the spread of grasses.
  3. Van Wilgen, B. W., et al. “Response of savanna fire regimes to changing fire‐management policies in a large African national park.” Conservation Biology 18.6 (2004): 1533-1540.  Approaches to fire management in the savanna ecosystems of the 2‐million ha Kruger National Park, South Africa, have changed several times over the past six decades. These approaches have included regular and flexible prescribed burning on fixed areas and a policy that sought to establish a lightning‐dominated fire regime. We sought to establish whether changes in management induced the desired variability in fire regimes over a large area. We used a spatial database of information on all fires in the park between 1957 and 2002 to determine elements of the fire regime associated with each management policy. The area that burned in any given year was independent of the management approach and was strongly related to rainfall (and therefore grass fuels) in the preceding 2 years. On the other hand, management did affect the spatial heterogeneity of fires and their seasonal distribution. Heterogeneity was higher at all scales during the era of prescribed burning, compared with the lightning‐fire interval. The lightning‐fire interval also resulted in a greater proportion (72% vs. 38%) of the area burning in the dry season. Mean fire‐return intervals varied between 5.6 and 7.3 years, and variability in fire‐return intervals was strongly influenced by the sequencing of annual rainfall rather than by management. The attempt at creating a lightning‐dominated fire regime failed because most fires were ignited by humans, and the policy has been replaced by a more pragmatic approach that combines flexible prescribed burning with lightning‐ignited fires.
  4. Beckage, Brian, Louis J. Gross, and William J. Platt. “Modelling responses of pine savannas to climate change and large‐scale disturbance.” Applied Vegetation Science 9.1 (2006): 75-82.  Global warming can potentially influence ecological communities through altered disturbance regimes in addition to increased temperatures. We investigate the response of pine savannas in the southeastern United States to global warming using a simple Lotka‐Volterra competition model together with predicted changes to fire and hurricane disturbance regimes with global climate change. In the southeastern United States, decreased frequency of both fires and hurricanes with global warming will shift pine savannas toward a forested state. A CO2 fertilization effect that increases the growth rate of tree populations will also push southeastern landscapes from open savannas towards closed forests. Transient dynamics associated with climate driven changes in vegetation will last on the order of decades to a century. In our model, the sensitivity of savannas to relative changes in the frequency of fire versus hurricanes is linearly dependent on the growth rate and mortality of trees in fire and hurricane disturbances.
  5. Govender, Navashni, Winston SW Trollope, and Brian W. Van Wilgen. “The effect of fire season, fire frequency, rainfall and management on fire intensity in savanna vegetation in South Africa.” Journal of Applied Ecology 43.4 (2006): 748-758.  Fire is important for the maintenance and conservation of African savanna ecosystems. Despite the importance of fire intensity as a key element of the fire regime, it is seldom measured or included in fire records. We estimated fire intensity in the Kruger National Park, South Africa, by documenting fuel loads, fuel moisture contents, rates of fire spread and the heat yields of fuel in 956 experimental plot burns over 21 years. Individual fires were conducted in five different months (February, April, August, October and December) and at five different return intervals (1, 2, 3, 4 and 6 years). Estimated fire intensities ranged from 28 to 17 905 kW m−1. Fire season had a significant effect on fire intensity. Mean fire intensities were lowest in summer fires (1225 kW m−1), increased in autumn fires (1724 kW m−1) and highest in winter fires (2314 kW m−1); they were associated with a threefold difference between the mean moisture content of grass fuels in winter (28%) and summer (88%). Mean fuel loads increased with post‐fire age, from 2964 kg ha−1 on annually burnt plots to 3972 kg ha−1 on biennial, triennial and quadrennial burnt plots (which did not differ significantly), but decreased to 2881 kg ha−1 on sexennial burnt plots. Fuel loads also increased with increasing rainfall over the previous 2 years. Mean fire intensities showed no significant differences between annual burns and burns in the biennial, triennial and quadrennial categories, despite lower fuel loads in annual burns, suggesting that seasonal fuel moisture effects overrode those of fuel load. Mean fire intensity in sexennial burns was less than half that of other burns (638 vs. 1969 kW m−1). We used relationships between season of fire, fuel loads and fire intensity in conjunction with the park’s fire records to reconstruct broad fire intensity regimes. Changes in management from regular prescribed burning to ‘natural’ fires over the past four decades have resulted in a decrease in moderate‐intensity fires and an increase in high‐intensity fires. The highest fire intensities measured in our study (11 000 – > 17 500 kW m−1) were significantly higher than those previously reported for African savannas, but were similar to those in South American cerrado vegetation. The mean fire intensity for late dry season (winter) fires in our study was less than half that reported for late dry season fires in savannas in northern AustraliaSynthesis and applications. Fire intensity has important effects on savanna vegetation, especially on the dynamics of the tree layer. Fire intensity varies with season (because of differences in fuel moisture) as well as with fuel load. Managers of African savannas can manipulate fire intensity by choosing the season of fire, and further by burning in years with higher or lower fuel loads. The basic relationships described here can also be used to enhance fire records, with a view to building a long‐term data set for the ongoing assessment of the effectiveness of fire management.
  6. Lucas, Chris, et al. “Bushfire weather in southeast Australia: recent trends and projected climate change impacts.” (2007).   [ [FULL TEXT PDF] Bushfires are an inevitable occurrence in Australia. With more than 800 endemic species, Australian vegetation is dominated by fire-adapted eucalypts. Fire is most common over the tropical savannas of the north, where some parts of the land burn on an annual basis. However, the southeast, where the majority of the population resides, is susceptible to large wildfires that threaten life and property. A unique factor in these fires of the southeast is the climate of the region. The southeast experiences a so-called Mediterranean climate, with hot, dry summers and mild, wet winters. The winter and spring rains allow fuel growth, while the dry summers allow fire danger to build. This normal risk is exacerbated by periodic droughts that occur as a part of natural interannual climate variability. Climate change projections indicate that southeastern Australia is likely to become hotter and drier in future. A study conducted in 2005 examined the potential impacts of climate change on fire- eather at 17 sites in southeast Australia. It found that the number of ‘very high’ and ‘extreme’ fire danger days could increase by 4-25% by 2020 and 15-70% by 2050. Tasmania was an exception, showing little increase. This report updates the findings of the 2005 study. A wider range of observations is analysed, with additional sites in New South Wales, South Australia and southeast Queensland included. The baseline dates of the study, commencing in 1973, are extended to include the 2006-07 fire season. The estimated effects of climate change by 2020 and 2050 are recalculated using updated global warming projections from the Intergovernmental Panel on Climate Change (IPCC). Two new fire danger categories are considered: ‘very extreme’ and ‘catastrophic’. This study also differs from the 2005 study in that different analysis methods are used. In addition to the annual changes in fire danger estimated before, changes to individual seasons and season lengths are explicitly examined. There is also a focus on the changes to the upper extremes of fire danger. These projected changes are compared with trends over the past few decades. Climate change projections: The primary source of data for this study is the standard observations made by the Bureau of Meteorology. The locations of the 26 selected observing stations are shown in Figure E1. At these stations, the historical record of Forest Fire Danger index (FFDI) and the likely impacts of future climate change are calculated. There are homogenization issues with the data that could affect the interpretation of the results, particularly the analysis of the current trends. However, estimates of the errors suggest that these are small enough that we can have confidence in the results. Climate change projections over southeastern Australia were generated from two CSIRO climate simulations named CCAM (Mark2) and CCAM (Mark3). Projected changes in daily temperature, humidity, wind and rainfall were generated for the years 2020 and 2050, relative to 1990 (the reference year used by the IPCC). These projections include changes in daily variability. They are expressed as a pattern of change per degree of global warming.
  7. Whitehead, Peter J., et al. “The management of climate change through prescribed savanna burning: emerging contributions of indigenous people in northern Australia.” Public Administration and Development: The International Journal of Management Research and Practice 28.5 (2008): 374-385.  Australia has committed to substantial cuts in greenhouse gas emissions (GHGE) achieved through a national emissions trading system, raising important issues for relatively undeveloped regions of Northern Australia and, in particular, Indigenous lands. Can mostly Indigenous and socio‐economically disadvantaged people living in such regions develop institutions to contribute significantly to the mitigation of GHGE, yet pursue regional development? Will national policies adequately recognise the special needs and potential contributions of such communities? These questions and the challenges inherent in them are addressed in this article with reference to a significant initiative involving the community management of landscape fire to reduce annual GHGE from savanna burning. This initiative appears to offer potential for engagement with global carbon markets, but it will need local, national and international support, along with appropriate changes in attitudes and legal arrangements, to ensure an equitable distribution of tangible rewards, while protecting the cultural and related benefits of customary fire use. Copyright © 2008 John Wiley & Sons, Ltd.
  8. Van Der Werf, Guido R., et al. “Climate controls on the variability of fires in the tropics and subtropics.” Global Biogeochemical Cycles 22.3 (2008).  In the tropics and subtropics, most fires are set by humans for a wide range of purposes. The total amount of burned area and fire emissions reflects a complex interaction between climate, human activities, and ecosystem processes. Here we used satellite‐derived data sets of active fire detections, burned area, precipitation, and the fraction of absorbed photosynthetically active radiation (fAPAR) during 1998–2006 to investigate this interaction. The total number of active fire detections and burned area was highest in areas that had intermediate levels of both net primary production (NPP; 500–1000 g C m−2 year−1) and precipitation (1000–2000 mm year−1), with limits imposed by the length of the fire season in wetter ecosystems and by fuel availability in drier ecosystems. For wet tropical forest ecosystems we developed a metric called the fire‐driven deforestation potential (FDP) that integrated information about the length and intensity of the dry season. FDP partly explained the spatial and interannual pattern of fire‐driven deforestation across tropical forest regions. This climate‐fire link in combination with higher precipitation rates in the interior of the Amazon suggests that a negative feedback on fire‐driven deforestation may exist as the deforestation front moves inward. In Africa, compared to the Amazon, a smaller fraction of the tropical forest area had FDP values sufficiently low to prevent fire use. Tropical forests in mainland Asia were highly vulnerable to fire, whereas forest areas in equatorial Asia had, on average, the lowest FDP values. FDP and active fire detections substantially increased in forests of equatorial Asia, however, during El Niño periods. In contrast to these wet ecosystems we found a positive relationship between precipitation, fAPAR, NPP, and active fire detections in arid ecosystems. This relationship was strongest in northern Australia and arid regions in Africa. Highest levels of fire activity were observed in savanna ecosystems that were limited neither by fuel nor by the length of the fire season. However, relations between annual precipitation or drought extent and active fire detections were often poor here, hinting at the important role of other factors, including land managers, in controlling spatial and temporal variability of fire.
  9. Roy, David P., et al. “The collection 5 MODIS burned area product—Global evaluation by comparison with the MODIS active fire product.” Remote sensing of Environment 112.9 (2008): 3690-3707.  The results of the first consecutive 12 months of the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) global burned area product are presented. Total annual and monthly area burned statistics and missing data statistics are reported at global and continental scale and with respect to different land cover classes. Globally the total area burned labeled by the MODIS burned area product is 3.66 × 106 km2 for July 2001 to June 2002 while the MODIS active fire product detected for the same period a total of 2.78 × 106 km2, i.e., 24% less than the area labeled by the burned area product. A spatio-temporal correlation analysis of the two MODIS fire products stratified globally for pre-fire leaf area index (LAI) and percent tree cover ranges indicate that for low percent tree cover and LAI, the MODIS burned area product defines a greater proportion of the landscape as burned than the active fire product; and with increasing tree cover (> 60%) and LAI (> 5) the MODIS active fire product defines a relatively greater proportion. This pattern is generally observed in product comparisons stratified with respect to land cover. Globally, the burned area product reports a smaller amount of area burned than the active fire product in croplands and evergreen forest and deciduous needleleaf forest classes, comparable areas for mixed and deciduous broadleaf forest classes, and a greater amount of area burned for the non-forest classes. The reasons for these product differences are discussed in terms of environmental spatio-temporal fire characteristics and remote sensing factors, and highlight the planning needs for MODIS burned area product validation.
  10. Archibald, Sally, et al. “What limits fire? An examination of drivers of burnt area in Southern Africa.” Global Change Biology 15.3 (2009): 613-630.  The factors controlling the extent of fire in Africa south of the equator were investigated using moderate resolution (500 m) satellite‐derived burned area maps and spatial data on the environmental factors thought to affect burnt area. A random forest regression tree procedure was used to determine the relative importance of each factor in explaining the burned area fraction and to address hypotheses concerned with human and climatic influences on the drivers of burnt area. The model explained 68% of the variance in burnt area. Tree cover, rainfall in the previous 2 years, and rainfall seasonality were the most important predictors. Human activities – represented by grazing, roads per unit area, population density, and cultivation fraction – were also shown to affect burnt area, but only in parts of the continent with specific climatic conditions, and often in ways counter to the prevailing wisdom that more human activity leads to more fire. The analysis found no indication that ignitions were limiting total burnt area on the continent, and most of the spatial variation was due to variation in fuel load and moisture. Split conditions from the regression tree identified (i) low rainfall regions, where fire is rare; (ii) regions where fire is under human control; and (iii) higher rainfall regions where burnt area is determined by rainfall seasonality. This study provides insights into the physical, climatic, and human drivers of fire and their relative importance across southern Africa, and represents the beginnings of a predictive framework for burnt area.
  11. Archibald, Sally, et al. “Climate and the inter‐annual variability of fire in southern Africa: a meta‐analysis using long‐term field data and satellite‐derived burnt area data.” Global Ecology and Biogeography 19.6 (2010): 794-809.  This study investigates inter‐annual variability in burnt area in southern Africa and the extent to which climate is responsible for this variation. We compare data from long‐term field sites across the region with remotely sensed burnt area data to test whether it is possible to develop a general model. Location Africa south of the equator. Methods Linear mixed effects models were used to determine the effect of rainfall, seasonality and fire weather in driving variation in fire extent between years, and to test whether the effect of these variables changes across the subcontinent and in areas more and less impacted by human activities. Results A simple model including rainfall and seasonality explained 40% of the variance in burnt area between years across 10 different protected areas on the subcontinent, but this model, when applied regionally, indicated that climate had less impact on year‐to‐year variation in burnt area than would be expected. It was possible to demonstrate that the relative importance of rainfall and seasonality changed as one moved from dry to wetter systems, but most noticeable was the reduction in climatically driven variability of fire outside protected areas. Inter‐annual variability is associated with the occurrence of large fires, and large fires are only found in areas with low human impact. Main conclusions This research gives the first data‐driven analysis of fire–climate interactions in southern Africa. The regional analysis shows that human impact on fire regimes is substantial and acts to limit the effect of climate in driving variation between years. This is in contrast to patterns in protected areas, where variation in accumulated rainfall and the length of the dry season influence the annual area burnt. Global models which assume strong links between fire and climate need to be re‐assessed in systems with high human impact.
  12. Archibald, Sally, et al. “Southern African fire regimes as revealed by remote sensing.” International Journal of Wildland Fire 19.7 (2010): 861-878.  Here we integrate spatial information on annual burnt area, fire frequency, fire seasonality, fire radiative power and fire size distributions to produce an integrated picture of fire regimes in southern Africa. The regional patterns are related to gradients of environmental and human controls of fire, and compared with findings from other grass-fuelled fire systems on the globe. The fire regime differs across a gradient of human land use intensity, and can be explained by the differential effect of humans on ignition frequencies and fire spread. Contrary to findings in the savannas of Australia, there is no obvious increase in fire size or fire intensity from the early to the late fire season in southern Africa, presumably because patterns of fire ignition are very different. Similarly, the importance of very large fires in driving the total annual area burnt is not obvious in southern Africa. These results point to the substantial effect that human activities can have on fire in a system with high rural population densities and active fire management. Not all aspects of a fire regime are equally impacted by people: fire-return time and fire radiative power show less response to human activities than fire size and annual burned area.
  13. Heckbert, Scott, et al. “Indigenous Australians fight climate change with fire.” Solutions: For A Sustainable & Desirable Future (2011).  The article focuses on the move of Indigenous people in Australia to implement fire management in an effort to improve landscape condition and reduce greenhouse gas emissions. It highlights the launch of the West Arnhem Land Fire Abatement (WALFA) project, a prime example of scientists, governments, Indigenous land managers, and carbon markets connecting to offer innovative solutions to resource management and economic development. It also highlights ecosystem services in the region.
  14. Bachelet, Dominique, et al. “Climate change impacts on western Pacific Northwest prairies and savannas.” Northwest Science 85.2 (2011): 411-429.  This paper represents a collaboration by conservation practitioners, ecologists, and climate change scientists to provide specific guidance on local and regional adaptation strategies to climate change for conservation planning and restoration activities. Our geographic focus is the Willamette Valley-Puget Trough-Georgia Basin (WPG) ecoregion, comprised of valley lowlands formerly dominated by now-threatened prairies and oak savannas. We review climate model strengths and limitations, and summarize climate change projections and potential impacts on WPG prairies and oak savannas. We identify a set of six climate-smart strategies that do not require abandoning past management approaches but rather reorienting them towards a dynamic and uncertain future. These strategies focus on linking local and regional landscape characteristics to the emerging needs of species, including potentially novel species assemblages, so that prairies and savannas are maintained in locations and conditions that remain well-suited to their persistence. At the regional scale, planning should use the full range of biological and environmental variability. At the local scale, habitat heterogeneity can be used to support species persistence by identifying key refugia. Climate change may marginalize sites currently used for agriculture and forestry, which may become good candidates for restoration. Native grasslands may increasingly provide ecosystem services that may support broader societal needs exacerbated by climate change. Judicious monitoring can help identify biological thresholds and restoration opportunities. To prepare for both future challenges and opportunities brought about by climate change, land managers must incorporate climate change projections and uncertainties into their long-term planning.
  15. Staver, A. Carla, Sally Archibald, and Simon Levin. “Tree cover in sub‐Saharan Africa: rainfall and fire constrain forest and savanna as alternative stable states.” Ecology 92.5 (2011): 1063-1072.  Savannas are known as ecosystems with tree cover below climate‐defined equilibrium values. However, a predictive framework for understanding constraints on tree cover is lacking. We present (a) a spatially extensive analysis of tree cover and fire distribution in sub‐Saharan Africa, and (b) a model, based on empirical results, demonstrating that savanna and forest may be alternative stable states in parts of Africa, with implications for understanding savanna distributions. Tree cover does not increase continuously with rainfall, but rather is constrained to low (<50%, “savanna”) or high tree cover (>75%, “forest”). Intermediate tree cover rarely occurs. Fire, which prevents trees from establishing, differentiates high and low tree cover, especially in areas with rainfall between 1000 mm and 2000 mm. Fire is less important at low rainfall (<1000 mm), where rainfall limits tree cover, and at high rainfall (>2000 mm), where fire is rare. This pattern suggests that complex interactions between climate and disturbance produce emergent alternative states in tree cover. The relationship between tree cover and fire was incorporated into a dynamic model including grass, savanna tree saplings, and savanna trees. Only recruitment from sapling to adult tree varied depending on the amount of grass in the system. Based on our empirical analysis and previous work, fires spread only at tree cover of 40% or less, producing a sigmoidal fire probability distribution as a function of grass cover and therefore a sigmoidal sapling to tree recruitment function. This model demonstrates that, given relatively conservative and empirically supported assumptions about the establishment of trees in savannas, alternative stable states for the same set of environmental conditions (i.e., model parameters) are possible via a fire feedback mechanism. Integrating alternative stable state dynamics into models of biome distributions could improve our ability to predict changes in biome distributions and in carbon storage under climate and global change scenarios.
  16. Price, Owen F., Jeremy Russell-Smith, and Felicity Watt. “The influence of prescribed fire on the extent of wildfire in savanna landscapes of western Arnhem Land, Australia.” International Journal of Wildland Fire 21.3 (2012): 297-305.  Fire regimes in many north Australian savanna regions are today characterised by frequent wildfires occurring in the latter part of the 7-month dry season. A fire management program instigated from 2005 over 24 000 km2 of biodiversity-rich Western Arnhem Land aims to reduce the area and severity of late dry-season fires, and associated greenhouse gas emissions, through targeted early dry-season prescribed burning. This study used fire history mapping derived mostly from Landsat imagery over the period 1990–2009 and statistical modelling to quantify the mitigation of late dry-season wildfire through prescribed burning. From 2005, there has been a reduction in mean annual total proportion burnt (from 38 to 30%), and particularly of late dry-season fires (from 29 to 12.5%). The slope of the relationship between the proportion of early-season prescribed fire and subsequent late dry-season wildfire was ~–1. This means that imposing prescribed early dry-season burning can substantially reduce late dry-season fire area, by direct one-to-one replacement. There is some evidence that the spatially strategic program has achieved even better mitigation than this. The observed reduction in late dry-season fire without concomitant increase in overall area burnt has important ecological and greenhouse gas emissions implications. This efficient mitigation of wildfire contrasts markedly with observations reported from temperate fire-prone forested systems.
  17. Archibald, Sally, A. Carla Staver, and Simon A. Levin. “Evolution of human-driven fire regimes in Africa.” Proceedings of the National Academy of Sciences 109.3 (2012): 847-852.  Human ability to manipulate fire and the landscape has increased over evolutionary time, but the impact of this on fire regimes and consequences for biodiversity and biogeochemistry are hotly debated. Reconstructing historical changes in human-derived fire regimes empirically is challenging, but information is available on the timing of key human innovations and on current human impacts on fire; here we incorporate this knowledge into a spatially explicit fire propagation model. We explore how changes in population density, the ability to create fire, and the expansion of agropastoralism altered the extent and seasonal distribution of fire as modern humans arose and spread through Africa. Much emphasis has been placed on the positive effect of population density on ignition frequency, but our model suggests this is less important than changes in fire spread and connectivity that would have occurred as humans learned to light fires in the dry season and to transform the landscape through grazing and cultivation. Different landscapes show different limitations; we show that substantial human impacts on burned area would only have started ∼4,000 B.P. in open landscapes, whereas they could have altered fire regimes in closed/dissected landscapes by ∼40,000 B.P. Dry season fires have been the norm for the past 200–300 ky across all landscapes. The annual area burned in Africa probably peaked between 4 and 40 kya. These results agree with recent paleocarbon studies that suggest that the biomass burned today is less than in the recent past in subtropical countries.
  18. Russell-Smith, Jeremy, et al. “Managing fire regimes in north Australian savannas: applying Aboriginal approaches to contemporary global problems.” Frontiers in Ecology and the Environment 11.s1 (2013): e55-e63. Savannas constitute the most fire‐prone biome on Earth and annual emissions from savanna‐burning activities are a globally important source of greenhouse‐gas (GHG) emissions. Here, we describe the application of a commercial fire‐management program being implemented over 28 000 km2 of savanna on Aboriginal lands in northern Australia. The project combines the reinstatement of Aboriginal traditional approaches to savanna fire management – in particular a strategic, early dry‐season burning program – with a recently developed emissions accounting methodology for savanna burning. Over the first 7 years of implementation, the project has reduced emissions of accountable GHGs (methane, nitrous oxide) by 37.7%, relative to the pre‐project 10‐year emissions baseline. In addition, the project is delivering social, biodiversity, and long‐term biomass sequestration benefits. This methodological approach may have considerable potential for application in other fire‐prone savanna settings. Savannas – defined broadly as tropical and subtropical grasslands (characterized by grasses with C4 photosynthetic pathway) with varying densities of tree cover – constitute the most fire‐prone ecosystems on Earth. They occupy one‐sixth of the planet’s land surface and support a tenth of the human population, and while rates of land‐use change are uncertain, these systems are likely to experience twice the rate of conversion as compared to tropical forests (White et al. 2000Grace et al. 2006). Almost 60% of savannas, and two‐thirds of the human populations that live in these areas, are located in sub‐Saharan Africa, with other major occurrences (in order of geographic extent) in Australia, South America, and Asia (White et al. 2000Lehmann et al. 2011). The deliberate burning of savannas, for a variety of agricultural, pastoral, and traditional management purposes, contributes as much as 10% of annual total global carbon (C) emissions and 44% of estimated C emissions from all sources of biomass burning (IPCC 2007van der Werf et al. 2010). Savannas constitute the most fire‐prone biome in the world. Although officially banned by government regulations in many countries, use of fire plays important roles in a range of savanna livelihood and biodiversity management applications. This paper discusses the application of a novel fire‐management project being undertaken by Aboriginal people in northern Australia that reduces greenhouse gas emissions from savanna fires.  [FULL TEXT]
  19. Pitman, ARCCSS Director Prof Andy. “Links between global warming and NSW bush fires.”  Submitted by astone on Fri, 10/25/2013 – 11:11, by ARCCSS Director Prof Andy Pitman:  A great deal has been said about the recent New South Wales bush fires and whether there is a link between these bush fires and global warming. An attempt to explain what is and is not known is provided here.First, some context setting. Bush fires have occurred in Australia for a long time. There is a history of fire in Australia exceeding 400,000 years with high variability in fire frequency associated with natural climate variability (Kershaw et al. 2002). A substantial increase in fire frequency occurred about 38,000 years ago. This was probably related to human activity given that there is little evidence for a coincident change in climate. A second peak in fire occurrence was associated with European settlement in 1788 (Kershaw et al. 2002). Currently, around 5% of the Australian land surface is burned annually consuming approximately 10% of the net primary productivity of the continent (Pittock 2003). So, fire is a natural phenomenon in Australia and a specific fire event as seen in the Blue Mountains in the last week is not caused by global warming. I am not aware of anyone who says it is. The questions are more around whether global warming is increasing the risk of bush fires, did global warming make the recent fires more likely and therefore whether there is a global warming link to the fires in the Blue Mountains. The risk of bush fire is driven by the amount and dryness of fuel, ambient weather and ignitions (Archibald et al., 2009). That is, you need fuel, you need hot and dry conditions and you need an ignition source. I’ll deal with what we know for each of these in turn. [FULL TEXT]

 

SAVANNA FIRES

 

AUSTRALIAN INDIGENOUS CONTROL BURNS

 

[LINK TO THE HOME PAGE OF THIS SITE]

[LIST OF TBGY POSTS]

 

THIS POST IS A CRITICAL REVIEW OF A TBGY VIDEO: [LINK TO YOUTUBE VIDEO]

HE EXPLAINS THAT CLIMATE CHANGE CAUSED THE AUSTRALIAN BUSHFIRES OF THE 2019-2020 BUSHFIRE SEASON.

THIS POST IS PRESENTED IN TWO PARTS. PART-1 IS A TRANSCRIPT OF THE TBGY YOUTUBE LECTURE & PART-2 IS A CRITICAL COMMENTARY ON THE CLAIMS MADE BY TBGY IN THE VIDEO LECTURE.

A RELATED POST CONTAINS THE RELEVANT BIBLIOGRAPHIC REFERENCES [LINK] 

 

ozmap

 

 

 

PART-1: TRANSCRIPT OF THE YOUTUBE VIDEO LECTURE

  1.  Right now as I am making this program, the eastern side of Australia from Queensland down to New South Wales is experiencing some much needed rainfall helping to ease the fires that have continued to burn there. This summer’s wildfires have been pretty much uncontrollable. As they have torn across great swathes of the country, they’ve tragically killed at least 25 people and torched about 11 million hectares of land – an area similar in size to the US State of Virginia or the European country of Bulgaria. Two thousand homes have been destroyed – an estimated cost of 700 million Australian Dollars, and more than a billion animals are thought to have been killed either directly by burning in the flames or by the loss of their natural habitat and food sources. bandicam 2020-02-02 17-32-56-060
  2. Like you, I am keen to understand what’s driven the extent of this year’s fires and whether climate change has had a real impact on their severity. So this week I’ve been having a look at what the SCIENTISTS are telling us; and it turns out that they’ve got quite a lot to say. When it comes to our planet’s climate, research over many years have shown that there is a multitude of influencing factors that combine in very complex and chaotic ways. And the factors determining timing, location, longevity, and severity of wildfires in Australia, and for that matter all the other geographical areas of the world, are no exception {??????} bandicam 2020-02-02 17-44-30-599
  3. Most folks know that bushfires are a naturally occurring event that happens each year in Australia. This is a paper on fire conditions in South Africa written by Sally Archibald and her research team in 2009  {This is a reference to Archibald, Sally, “What limits fire? An examination of drivers of burnt area in Southern Africa.” Global Change Biology 15.3 (2009): 613-630 included in the bibliography below paragraph#11}. It outlines the four main requirements for wildfires to get going, none of which will come as a great surprise. They are: (1) Hot and dry ambient weather, (2) The availability of fuel, (3) The fuel to be dry and combustible, (4) An ignition source. bandicam 2020-02-02 18-54-30-240
  4. So how has recent human induced climate change had a bearing on any of those factors? Well, there is plenty of research showing how our planet’s average atmospheric temperature is on the rise. The NOAA in the United States released this report on the 15th of January, 2020 showing that 2019 was the second hottest year for our planet just behind 2016 which was a strong El Nino year. bandicam 2020-02-02 19-00-13-047
  5. And in fact the government Bureau of Meteorology over in Australia released their own climate statement on the 9th of January 2020 showing that 2019 was the hottest Australian year on record with temperatures of 1.5C to 2C above the 1961-1990 average. bandicam 2020-02-02 19-05-10-124
  6. This chart released by the bureau shows the areas affected with white areas denoting average temperature, yellow areas being above average, light orange areas very much above average, and the dark orange bit experiencing the highest temperatures on record. You can clearly see how New South Wales was severely impacted. In fact it recorded 2019 average temperatures some 1.95C above the 1961-1990 average breaking the previous 2018 record by 0.27C. bandicam 2020-02-02 19-10-58-394
  7. The overwhelming scientific evidence is that human emissions of carbon dioxide and other greenhouse gases are by far the main drivers of increased global average atmospheric temperatures since the beginning of the Industrial Revolution – the planet’s average temperature now standing at 1.05C warmer than 1860 levels. bandicam 2020-02-02 19-20-43-773
  8. But other research is showing that those increased CO2 levels are also exacerbating the second criterion outlined in Sally Archibald’s research – availability of fuel. This is a paper written in 2013 by Professor Andy Pitman (see bibliography below paragraph #19) of the Australian government’s research center for “Climate System Science”. It explains how increased CO2 levels in the atmosphere act as a fertilizer for the plants and trees of the native Australian bush. And that causes an increase in the net {green leaf?} productivity. An increase in greenery sounds like it might be a good thing for out planet but the “paper” (the Pitman manuscrpt) points out that in this case the increase isn’t sustainable over the long term because it is limited by the availability of nutrients. Farmers very successfully use very high levels of CO2 in their greenhouses to promote strong plant growth but they can only achieve that because in that controlled environment they provide the right amount of water and fertilizer into the mix to ????? crops. No such water or fertilizer is available in the Australian bush. Pitman makes the observation that when vegetation takes up CO2 it fixes it as carbon in leaves, woody matter, and ??????. If our planet’s biosphere takes up the high level of carbon dioxide now available in the atmosphere, Pitman argues, it’s inevitable the biosphere will also be fixing more carbon. More carbon fixed or locked up in woody matter means more fuel for fire. And if the green vegetation also uses the additional carbon to produce more leaves, when those leaves drop you’ve got even more potential fire fuel lying around on the ground. While the paper points out that more fuel on the ground doesn’t in itself lead to more fires, it does mean that whenever a fire breaks out, it’s got much more fuel available to keep on burning. bandicam 2020-02-02 21-11-11-624
  9. That fuel has to be dry of course as our original list of criteria points out. So how’s that been working out down under? Well, let’s go back to that 2019 climate statement from the Aussie Bureau of Meteorology. It sounds as if 2019 was the driest year on record there with rainfall 40% lower than average based on records going back to 1900. Much of Australia was hit by drought in 2019 with New South Wales and Queensland both affected particularly severely. Most of us would instinctively expect that those warmer temperatures we just looked at would probably play a big part in causing the surface of the land to become drier through evaporation and warm air circulation. Fair enough! bandicam 2020-02-03 10-22-19-730
  10. But researchers have been discovering some less obvious factors that are also contributing to the excessive dryness of the region. The Bureau of Meteorology tells us that as our human greenhouse gas emissions continue to increase, that increase isn’t just resulting in higher levels of CO2 fixing that we looked at earlier, it is also causing the length of the growing season to extend in many parts of Australia. This chart shows the 30-year trend in growing season length between 1971 and 2011. bandicam 2020-02-03 10-29-34-704
  11. The size of the red bubbles shows the increased length of the growing season in that location with some parts of the continent experiencing increases in growing season extended by 20 days or more each decade. Professor Pitman’s 2013 paper explains that these longer growing seasons means more moisture is being sucked from the ground by trees and vegetation. And that moisture is then transferred back into the atmosphere as those plants transpire – which inevitable leads to drier earth. And as an added further irony there is also strong evidence that the huge amount of carbon dioxide currently being released by the bushfires are unlikely to get re-absorbed back into the ground through re-growth of forest the way they used to do in the balanced Australian climate systems of the past. bandicam 2020-02-03 10-41-10-430
  12. So that’s a whole load of CO2 now up in the atmosphere causing more warming. And the globally interconnected nature of our whole planet’s climate system brings a couple of other elements into play too as the Met Bureau goes on to highlight. Firstly, there is something called the Indian Ocean Dipole. The Dipole is an irregular movement of sea surface temperatures which, according to science speak, can have phases that are positive, negative, or neutral. In 2019, the Dipole was in a positive phase which meant that the Indian Ocean off Australia’s Northwest Coast was cooler than normal. Positive Dipole events like this tend to draw moisture away from Australia and deliver less rainfall. But surely that’s a natural random event that’s always been there and there’s nothing we humans can do about something like that. We just have to put it down to bad timing on this occasion, right? bandicam 2020-02-03 18-19-37-543
  13. And …. NO! Because, once again, climate scientists are discovering increasingly strong evidence that those pesky human induced greenhouse gas emissions are having an impact on the Indian Ocean Dipole as well. This 2018 study in the journal Nature Communications found that if our planet does reach the global average temperature of 1.5C above pre-industrial levels, which is highly likely in the next couple of decades, then the frequency of extreme positive phase dipoles in the Indian Ocean looks set to double as a result. The full explanation of how and why that happens is outside the scope of this program. bandicam 2020-02-03 18-49-45-622
  14. But I’ll link that study and the papers and reports in the comments section below. So if you want to delve into the details you can grab everything you need from there. I did say there were a couple of extra elements highlighted by the Met Bureau and the second element is the Southern Annular Mode or SAM. The SAM is a north-south cyclical movement of strong westerly winds that blow almost continuously in the mid to high latitudes of the Southern Hemisphere. The winds cause storms and cold fronts that bring rainfall to southern Australia. Just like the Indian Ocean Dipole, the SAM has three phases – neutral, positive, and negative. As the Australian ???? November and December of 2019, a sudden warming event in the stratosphere above Antarctica nudged the SAM into a negative phase which caused those winds to track further north blowing hot air across the country fanning the flames and increasing the intensity of the fires. That unexpected negative phase of the SAM provided an extremely unhelpful short-term further boost to the bushfire crisis. bandicam 2020-02-03 18-53-47-440
  15. This paper by Professor Nerilie Abram, a climate scientists at the Australian National University, finds evidence actually suggesting that climate change generally appears to be pushing SAM toward more positive phases. But when those positive phases are prominent during Australia’s winter time, the ensuing winds have the effect of increasing the levels of dryness across the continent. And a kind of metaphorical macabre icing on the combustible cake is this 2019 paper by Andrew Dowdy finds evidence that global warming is causing more favorable conditions for a self re-enforcing phenomenon known as pyrocumulonimbus or pyrocb ?perform? as extreme bushfires can become coupled with the atmosphere generating their own lightning and gusty, violent and unpredictable winds. bandicam 2020-02-03 21-51-17-209
  16. These horrendous meteorological events replace rainfall with blackened hail and embers that can be shot over distances of 30 km making wildfire events much more dangerous. And as to the ignition source, well, earlier this month which I am sure many of you have no doubt seen, Twitter lit up with claims of a big wave of arson driving the bushfires this year. Even the President of the United States of America and his best budd Sean Hannity got into the hashtag arson emergency push, both re-tweeting allegations that close to 200 people in Australia have been charged with arson for deliberately lighting fires. It’s almost as if they were trying o suggest that the fires had nothing to do with climate change and was entirely cooked up by a group of pyromaniacs. Well there’s no doubt that some arsonists have been active in the current bushfire season as they apparently are every year in Australia. New South Wales police say they actually only charged 24 people with deliberately lighting bushfires this season. {According to BBC News [LINK] “The widely circulated figure of nearly 200 people arrested for deliberately starting fires is inaccurate. Police in New South Wales said in January 183 people had been charged since November 2019 over “bushfire-related offences”. Of those, 24 were accused of deliberately lighting fires. The rest were over failures to comply with total fire bans such as lighting a campfire or things such as discarding cigarettes or matches. Queensland Police say of the 1,068 bushfires in the state since September, 114 (about 10%) have been “deliberately or maliciously lit through human involvement”} bandicam 2020-02-04 10-41-55-939
  17. And officials in the State of Victoria have also refuted arson as a major cause of bushfires. A police spokesman said, “Police are aware of a number of posts circulating in relation to the current bushfire situation, however, currently there is no intelligence to indicate that the fires in East Gippsland and Northeast Victoria have been caused by arson or by any other suspicious behavior. Of course all sorts of things can get a fire started during hot weather when the ground is tinder dry. Clumsy human error and accidents certainly play their parts, but according to Dale Dominey Howes, Professor of “Hazard and Disaster Risk Sciences” at the University of Sydney, the main cause of fire ignition in Australia’s bushfires is dry lightning – essentially lightning from thunderstorms that don’t produce rain. bandicam 2020-02-04 11-00-28-133
  18. Whatever the source of ignition may be though, it does appear that our rapidly changing climate is playing a significant role in producing the perfect conditions for Australian wildfires to become progressively longer lasting and more severe in the coming years. Australia’s National Environmental Science Program was very clear in its view when it published this advice back in November of 2019 stating “Human caused climate change has resulted in more dangerous weather conditions for bushfires in recent decades for many regions of Australia. Observations show a trend towards more dangerous conditions during summer, and an earlier start to the fire season, particularly in parts of Southern and Eastern Australia. These trends are very likely to increase into the future, with climate models showing more dangerous weather conditions for bushfires throughout Australia due to increasing greenhouse gas emissions.  bandicam 2020-02-04 11-05-42-710
  19. The President of the Australian Academy of Sciences, Professor John Shine, said Australia must take stronger action as part of the worldwide commitment to limit global warming to 1.5C above the long term average to reduce the worst impacts of climate change. And Nerilie Abram, who did that research on the Southern Annular mode, said “Even from my perspective, I’m surprised by just how bad 1C of warming is looking. It’s worrying that we are talking about this as a new normal because we are actually on an upward trajectory. Currently, the pledges in the Paris Agreement are not enough to limit us to 1.5C. We are looking more like 3C.

 

 

PART-2: CRITICAL COMMENTARY

  1. CLAIM: When it comes to our planet’s climate, research over many years have shown that there is a multitude of influencing factors that combine in very complex and chaotic ways. And the factors determining timing, location, longevity, and severity of wildfires in Australia, and for that matter all the other geographical areas of the world, are no exception. RESPONSE: That “a multitude of factors determine timing, location, and longevity of wildfires in Australia in complex and chaotic ways” does not imply that we understand these relationships in a deterministic way to be able to use them ether to relate the bushfires to AGW or to formulate out policy objectives and appropriate response to the bushfires. It means that we don’t really know because the relationship is complex and chaotic. If it is chaotic, it is not deterministic.
  2. CLAIM: This is a paper on fire conditions in South Africa written by Sally Archibald and her research team in 2009. It outlines the four main requirements for wildfires to get going, none of which will come as a great surprise. They are: (1) Hot and dry ambient weather, (2) The availability of fuel, (3) The fuel to be dry and combustible, (4) An ignition source.   RESPONSE: The Archibald 2009 paper is listed in the bibliography post [LINK] . It does not outline “the four main requirements for wildfires to get going“. It studies burned areas to estimate the factors that determine the burned area fraction. Her model explained 68% of the variance in burned fraction implying that there are other factors possibly the amount of grazing, roads per unit area, population density, and cultivation fraction. In a 2010 paper she presents a further test for burned area fraction determinants and finds that burned fraction is associated with the occurrence of large fires, and large fires are only found in areas with low human impact. The more wilderness you have, the larger the burned fraction.
  3. CLAIM: So how has recent human induced climate change had a bearing on any of those factors? Well, there is plenty of research showing how our planet’s average atmospheric temperature is on the rise. The NOAA in the United States released this report on the 15th of January, 2020 showing that 2019 was the second hottest year for our planet just behind 2016 which was a strong El Nino year. And in fact the government Bureau of Meteorology over in Australia released their own climate statement on the 9th of January 2020 showing that 2019 was the hottest Australian year on record with temperatures of 1.5C to 2C above the 1961-1990 average. RESPONSE: The presumption that AGW  had a role in he fires is a confirmation bias that distorts research in this area as well as the management of forest areas. Besides, the citation of temperature extremes as evidence of AGW reflects a gross misunderstanding of AGW theory which relates only to long term trends in global mean temperature and not to temperature events. Temperature events are probably more dramatic and make for better fear mongering but they do not contain relevant or useful AGW information. They are used only for dramatic effect by climate activists.
  4. CLAIM: This chart released by the Bureau shows the areas affected with white areas denoting average temperature, yellow areas being above average, light orange areas very much above average, and the dark orange bit experiencing the highest temperatures on record. You can clearly see how New South Wales was severely impacted. In fact it recorded 2019 average temperatures some 1.95C above the 1961-1990 average breaking the previous 2018 record by 0.27C.
  5. RESPONSE: What we “clearly see” here is that there are hot areas, very hot areas, and not so hot areas in Australia and that is what we would expect to see as a uniform continental temperature would be an extremely rare event. And indeed some hot and very hot areas occur in New South Wales along with some not so hot areas. This temperature graphic does not show that New South Wales was “severely impacted” or that it was impacted at all. Impacted by what? If you mean that it was “impacted” by climate change you would have to provide empirical evidence of such impact – not just a claim of convenience. Also, that the average NSW temperature was 1.95C above the 1961-1990 average doesn’t have any interpretation in terms of the effect of AGW warming on bushfires. In long term warming since pre-industrial times, short term warming often fluctuates wildly around the mean as seen in the chart below where mean Southern Hemisphere land temperatures are used. The difference would be even more dramatic for smaller regions within the Southern Hemisphere. CRUTEM-SH
  6. CLAIM: The overwhelming scientific evidence is that human emissions of carbon dioxide and other greenhouse gases are by far the main drivers of increased global average atmospheric temperatures since the beginning of the Industrial Revolution – the planet’s average temperature now standing at 1.05C warmer than 1860 levels. RESPONSE: Why is warming computed from the year 1860? Is the overwhelming scientific evidence that human emissions of carbon dioxide and other greenhouse gases began driving up the temperature in 1860? Exactly when did this process begin? What does the overwhelming scientific evidence say about that? I can tell you that NASA and James Hansen will not agree as they claim that human caused warming began in 1950. The very first AGW paper published was Callendar 1938 where he writes that human caused global warming began in 1900 and warmed steadily from there until 1938. But Callendar’s was was mostly set aside when the 1940s-1970s cooling took hold and the research emphasis shifted to the cooling effect of the aerosols of the industrial economy. Modern climate scientists therefore take two different positions on the sensitive matter of when AGW began. The Americans (James Hansen and NASA) go to the depth of the 1940s-1970s cooling and begin their AGW in 1950. The British (Peter Cox for example) take the more rational approach and begin when the 1940s-1970s cooling had ended in the late 1970s. Neither group reaches back to 1860. Another consideration is the work of Colin Morice of CRU who found an unacceptable level of uncertainty in the early part of the HadCRU temperature dataset.
  7. CLAIM: Professor Andy Pitman of the Australian government’s research center for “Climate System Science”. It explains how increased CO2 levels in the atmosphere act as a fertilizer for the plants and trees of the native Australian bush. And that causes an increase in the net green leaf productivity; but in this case the increase isn’t sustainable over the long term because it is limited by the availability of nutrients. Farmers very successfully use very high levels of CO2 in their greenhouses to promote strong plant growth but they can only achieve that because in that controlled environment they provide the right amount of water and fertilizer into the mix.  RESPONSE: It is true that in Greenhouses with high levels of CO2 must add the proportional amount of water and nutrient to the soil to avoid the production of agricultural products that are deficient in nutrient. However, greenhouses operate at 2000 ppm CO2 and higher. It is this radical change from atmospheric conditions that requires special attention to soil properties to match CO2 levels that are driving the plant’s photosynthesis operation. However, in the Mauna Loa era, with at atmospheric CO2 increase from 315 to 415 ppm the difference is not large enough to be a factor in the context of natural variability in soil conditions.
  8. CLAIM:  It sounds as if 2019 was the driest year on record in Australia with rainfall 40% lower than average based on records going back to 1900. Much of Australia was hit by drought in 2019 with New South Wales and Queensland both affected particularly severely. Most of us would instinctively expect that those warmer temperatures we just looked at would probably play a big part in causing the surface of the land to become drier through evaporation and warm air circulation. Fair enough!  RESPONSE: Australia is a semi arid place known for periodic hot and hot dry spells. The implication of the attribution to AGW is that since 2019 was the hottest year on record and since AGW causes temperatures to rise, therefore the 2019 dry year must have been caused by AGW. This kind of attribution of convenience to serve the activism needs of the climate movement is not science. It is a form of naked activism driven by an inner confirmation bias so deeply entrenched that it appears to be logical to the activist.
  9. CLAIM: The Bureau of Meteorology tells us that as our human greenhouse gas emissions continue to increase, that increase is causing the length of the growing season to extend in many parts of Australia. The 30-year trend in growing season length between 1971 and 2011 shows a dramatic increase growing by 20 days or more per decade. In the longer growing seasons more moisture is being sucked up from the ground by trees and vegetation and that moisture is then transferred back into the atmosphere as those plants transpire – which inevitable leads to drier earth. RESPONSE: The higher level of atmospheric CO2 doesn’t drive plants crazy such that they go overboard with photosynthesis and suck up all the water from the ground to cause dryness. Plants balance their photosynthesis activity with water availability. When running short of water, they close the stomata and conserve water and take in less carbon dioxide and slow down photosynthesis even in the presence of higher atmospheric CO2.
  10. CLAIM: And as an added further irony there is also strong evidence that the huge amount of carbon dioxide currently being released by the bushfires are unlikely to get re-absorbed back into the ground through re-growth of forest the way they used to do in the balanced Australian climate systems of the pastRESPONSE: AGW climate change is not a theory about whether the carbon cycle or temporary and natural changes in the carbon cycle cause warming. It is very specific about fossil fuels as the driver of AGW because it represents EXTERNAL carbon that had been sequestered from the carbon cycle for millions of years. It is thought that when this external carbon that does not belong in the current account of the carbon cycle is injected into the delicately balanced current account of the carbon cycle and climate system, it can destabilize the carbon cycle and  cause CO2 accumulation and thereby destabilize the climate system. CO2 emissions of forest fires are part of the current account of the carbon cycle and therefore have no role in AGW theory.
  11. CLAIM: The balanced Australian climate systems of the past.  RESPONSE: There is a tendency among climate activists to paint a climate history of the world or any part thereof in terms of a stable “balanced” climate system of the past before fossil fuels came along and a wild and crazy unbalanced climate system of the present that is a creation of fossil fuel emissions. Paleo data do not support this view. For example the data show that the whole of the Holocene has been cycling through violent and chaotic warming and cooling cycles at centennial and millennial time scales [LINK] . In Verdon etal 2006 we find that in the last 400 years climate shifts associated with changes in the PDO and ENSO have occurred with a similar frequency to those documented in the 20th Century. In his 2007 paper he writes “the long-term behaviour of the Interdecadal Pacific Oscillation (IPO) and the El Niño/Southern Oscillation (ENSO) is used to develop a stochastic framework for generating rainfall replicates to be used in assessing long-term hydrologic drought risk for water resource management in NSW. The rainfall replicates demonstrate that this region may have experienced meteorological droughts of longer duration than has been recorded by the instrumental record. [LINK]
  12. CLAIM: So that’s a whole load of CO2 now up in the atmosphere causing more warming.  RESPONSE: This irrational fear of carbon cycle carbon is the likely reason for the decline and fall of proper forest management methods that involve prescribed control burns. The resultant failure to manage forests may be a big part of the problem in Australia where climate sensibility has overcome common sense. It may be time for the white man to learn from the Indigenous people of Australia who have been using control burns to manage bushfires for ages.indi-1
  13. CLAIM: Firstly, there is something called the Indian Ocean Dipole. The Dipole is an irregular movement of sea surface temperatures which, according to science speak, can have phases that are positive, negative, or neutral. In 2019, the Dipole was in a positive phase which meant that the Indian Ocean off Australia’s Northwest Coast was cooler than normal. Positive Dipole events like this tend to draw moisture away from Australia and deliver less rainfall. But surely that’s a natural random event that’s always been there and there’s nothing we humans can do about something like that. We just have to put it down to bad timing on this occasion, right? And …. NO! Because, once again, climate scientists are discovering increasingly strong evidence that those pesky human induced greenhouse gas emissions are having an impact on the Indian Ocean Dipole as well. This 2018 study in the journal Nature Communications found that if our planet does reach the global average temperature of 1.5C above pre-industrial levels, which is highly likely in the next couple of decades, then the frequency of extreme positive phase dipoles in the Indian Ocean looks set to double as a result. RESPONSE: This is a reference to the Wenju Cai 2018 paper [LINK] in which he found that climate models show that the frequency of extreme positive Indian Ocean Dipole will double at 1.5 °C warming.  This climate model projection has not been tested with data and therefore no empirical evidence exists to verify such a causal relationship between warming and the IOD. This proposition therefore stands as a theoretical curiosity and not as a finding that can be used to make policy decisions.
  14. CLAIM: This paper by Professor Nerilie Abram finds evidence suggesting that climate change is pushing SAM toward more positive phases. A 2019 paper by Andrew Dowdy finds evidence that global warming is causing more favorable conditions for a self re-enforcing phenomenon known as pyrocumulonimbus. Extreme bushfires can become coupled with the atmosphere generating their own lightning and gusty, violent and unpredictable winds. RESPONSE: Nerilie Abram did not find evidence that climate change is pushing SAM toward more positive values. In her 2014 paper she writes that “Predictions of further greenhouse-driven increases in the SAM over the coming century need to account for the possibility of opposing effects from tropical Pacific climate changes“.  Andrew Dowdy simply describes the physics and the horror of the pyrocumulonimbus event on Black Saturday in the 2009 Australian bushfire season {Pyro (fire) cumulo (flat and puffy clouds) nimbus (high clouds that produce rain}. In an intense and large fire the large convective air and fire flow upwards can consume cumulus and nimbus clouds into one large fire-cloud system that can create lightning, thunderstorms, and even tornadoes by the sheer force and energy of the fire driven convection – as seen in the video below. These things form naturally in large and intense fires in open savanna regions and are  not a product of AGW climate change. 
  15. CLAIM:  Well, earlier this month which I am sure many of you have no doubt seen, Twitter lit up with claims of a big wave of arson driving the bushfires this year. Even the President of the United States of America and his best buddy Sean Hannity got into the hashtag arson emergency push, both re-tweeting allegations that close to 200 people in Australia have been charged with arson for deliberately lighting fires. It’s almost as if they were trying o suggest that the fires had nothing to do with climate change and was entirely cooked up by a group of pyromaniacs. Well there’s no doubt that some arsonists have been active in the current bushfire season as they apparently are every year in Australia. New South Wales police say they actually only charged 24 people with deliberately lighting bushfires this season. RESPONSEAccording to BBC News [LINK] “The widely circulated figure of nearly 200 people arrested for deliberately starting fires is inaccurate. Police in New South Wales said in January 183 people had been charged since November 2019 over “bushfire-related offences”. Of those, 24 were accused of deliberately lighting fires. The rest were over failures to comply with total fire bans such as lighting a campfire or things such as discarding cigarettes or matches. Queensland Police say of the 1,068 bushfires in the state since September, 114 (about 10%) have been “deliberately or maliciously lit through human involvement”
  16. CLAIM: It appears that our rapidly changing climate is playing a significant role in producing the perfect conditions for Australian wildfires to become progressively longer lasting and more severe in the coming years. Australia’s National Environmental Science Program was very clear in its view when it published this advice back in November of 2019 stating “Human caused climate change has resulted in more dangerous weather conditions for bushfires in recent decades for many regions of Australia. Observations show a trend towards more dangerous conditions during summer, and an earlier start to the fire season, particularly in parts of Southern and Eastern Australia. These trends are very likely to increase into the future, with climate models showing more dangerous weather conditions for bushfires throughout Australia due to increasing greenhouse gas emissions. RESPONSE: How was it determined that AGW climate change is playing a significant role in producing the perfect conditions for Australian wildfires to become progressively longer lasting and more severe in the coming years? No evidence for this relationship is provided or cited. It appears instead, that all bad things are instinctively assumed to be related to AGW and with a trend going from bad to worse. This kind of confirmation bias is not science but superstition. 
  17. SUMMARY: No evidence is found in the TBGY video that AGW causes Australian bushfires to become more extreme and destructive but rather the presentation appears to show that climate activism against CO2 emissions does so by opposing prescribed control burns. Also, if natural disasters really are more tragic and damaging than they were before the AGW era, then a possible reason for that is that AGW climate change activism for climate action needs them to be. What follows from that is knee-jerk attribution of the horror to AGW and then a call for climate action to save the planet from such horrors. 

 

 

EXTRACTS FROM THE “BUSHFIRES AND GLOBAL WARMING” PAGE  [LINK]

  1. Decades of research and experience has demonstrated that fuel reduction by prescribed burning under mild conditions is the only proven, practical method to enable safe and efficient control of high-intensity forest fires.
  2. Two myths have emerged about climate change and bushfire management and are beginning to circulate in the media and to be adopted as fact by some scientists. They are (1) “Because of global warming, Australia will be increasingly subject to uncontrollable holocaust-like “megafires” and (2) Fuel reduction by prescribed burning must cease because it releases carbon dioxide into the atmosphere, thus exacerbating global warming and the occurrence of megafires.
  3. Both statements are incorrect. However they represent the sort of plausible-sounding assertions which, if repeated often enough, can take on a life of their own and lead eventually to damaging policy change.
  4. The full text of this excellent blog post by professionals in Australia is available online [LINK] .

 

EXTRACTS FROM THE “WHAT FIREFIGHTERS SAY” PAGE [LINK] 

  1. Ask any fire-fighter : prescribed burning mitigates bushfire losses.
  2. The purpose of a fuel-reduction burning program is not to stop bushfires, but to assist with their safe suppression.
  3. Prescribed burning, done properly, is highly effective at mitigating the bushfire threat, and assists with the control of fires even under severe weather conditions.
  4. Reducing fuel loads and simplifying fuel structures by regular burning reduces the speed of a bushfire, its intensity, the size of the flames and its ember and spotting potential and that makes bushfires easier to put out and less damaging.
  5. In the AGW era, the effects of bad fire management can be attributed to climate change and thus releasing managers from accountability.

 

 

COMMENT BY GREG LUCKIE ON YOUTUBE   [LINK]

Highlighting by blog author

A cleverly orchestrated and contrived presentation. But not entirely accurate. Gippsland fire was deliberately lit. Also there were in excess of a 100 people in NSW charged with deliberately, carelessly, recklessly, mischievously lighting fiers. In the Northern Territory, one man charged with lighting 17 fires, another person is being investigated. IOD & SAM are not the only climate drivers in play, MJO & ENSO also come in to play. They all are driven by the sun, not AGW. The sun is in solar minimum affecting the jet-stream. 2019, the driest year, and yet floods in QLD and Lake Eyre filled with water, go figure. Poor land management, not AGW is the reason for the fire intensity. The effects of the drought were exacerbated by government failure to properly manage existing water resources. This resulted in megalitres of usable water being flushed in to the southern ocean. This is still happening. 2008, 2015 and again 2019 David Packham, former CSIRO bushfire scientist, issued the following warning, forget global warming. It’s the reckless failure to burn-off fuel loads that have turned parts of Australia into death traps. When will we learn? Yet no one listened. https://www.theage.com.au/national/victoria/bushfire-scientist-david-packham-warns-of-huge-blaze-threat-urges-increase-in-fuel-reduction-burns-20150312-14259h.html. 2008 report on Bushfires, Prescribed Burning and Global Warming. https://www.bushfirefront.org.au/resources-2/further-reading/bushfires-and-global-warming/

 

 

 

 

 

PYROCUMULONIMBUS VIDEO