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THIS POST IS A CRITICAL REVIEW OF THE KAUPPINEN & MALMI 2019 HYPOTHESIS  [LINK] THAT THE THEORY OF AGW CLIMATE CHANGE HAS FALSELY ATTRIBUTED WARMING TO RISING ATMOSPHERIC CO2 CONCENTRATION WHEN MOST OF THE WARMING CAN BE EXPLAINED IN TERMS OF ALBEDO LOSS FROM A DECLINE IN LOW CLOUD COVER. 

 

FIGURE 1: LOW CLOUD COVER 1983-2008 [SOURCE]

 

FIGURE 2: HIGH CLOUD COVER 1983-2005 [SOURCE] 

 

FIGURE 3: TROPICAL LOW CLOUD & TEMPERATURE 1983-2011 [SOURCE] 

FIGURE 4: GLOBAL WARMING ABOVE & BELOW LOW CLOUDS 1979-2019COMPARE-TRENDSCOMPARE-TSTAT

 

FIGURE 5: CORRELATIONS: CO2 FORCING AND TEMPERATURE 1979-2019 

 

FIGURE 6: KAUPPINEN & MALMI FIGURES 2&3

 

  1. The Kauppinen & Malmi 2019 paper (KM2019) [LINK] with the provocative title “NO EXPERIMENTAL EVIDENCE FOR THE SIGNIFICANT ANTHROPOGENIC CLIMATE CHANGE” (SIC), uses recently published satellite data for low cloud cover (Figure 1) along with HadCRUT4 global surface temperature data to display a visual correlation between temperature and low cloud cover (Figure 6).  Obvious departures from the correlation are  explained in terms of the 1991 Mt Pinatubo eruption (temperature too low) and the strong 1998 El Nino (temperature too high) and concludes that declining low cloud cover, and not rising atmospheric CO2 concentration, explains global warming.
  2. Based on the charts of overlaid temperature and low cloud cover data shown in Figure 6 (See Figure 2 and Figure 3 in the source document [LINK] ), the authors claim that the observed warming trend in surface temperature is explained by declining low cloud cover and not by rising atmospheric CO2. The rationale for the low cloud effect is that clouds reflect incoming solar radiation and that therefore rising cloud cover causes cooling and declining cloud cover causes warming. The decline in low cloud cover in the study period 1983 to 2008 is well established in the ISSCP datasets [LINK] and is displayed above in Figure 1. A relationship between low cloud cover over and temperature over the tropics is presented in the Climate4You blog [SOURCE] and is displayed in Figure 3 above. It shows rising temperature in the tropics coincident with declining low cloud cover and appears to be consistent with the KM2019 finding that the declining low cloud cover (LCC) causes warming globally and not just in the tropics. The causation rationale is that clouds reflect incoming solar radiation and thus lower surface temperature.
  3. It is noted however, that correlation between time series source data do not always imply causation and that when they do, no information about the direction of the causation can be inferred from these data. For example, in {McCoy, Daniel T., et al. “The change in low cloud cover in a warmed climate inferred from AIRS, MODIS, and ERA-Interim.” Journal of Climate 30.10 (2017): 3609-3620} the authors find that warming surface temperatures have caused a decline in low cloud cover over sub-tropical regions in the same period of study as the KM2019 paper. The reverse causation is suggested in the Somerville 1985 paper in which he finds that CO2 induced global warming is self correcting because warming increases cloud formation and clouds reflect sunlight back into space. {Richard Somerville, Scripps Institute of Oceanography, UC San Diego}. 
  4. An added complication is that in the instrumental record, global warming is found mostly in nighttime daily TMIN and not in daytime daily TMAX  {Related posts [LINK] [LINK] }. G. Kukla, PD Jones, and others (Kukla 1993) describe this apparent anomaly in terms of low cloud cover that reflects solar radiation upward and the earth’s long wave radiation downward. At night, with no solar radiation to reflect upward, the net effect of low clouds is warming by reflecting terrestrial radiation downward. The relationship between low cloud cover and warming is therefore more complicated than the reflection of solar radiation upward.
  5. The significant claim of the KM2019 paper relating to AGW is that since the observed warming in surface temperature can be explained in terms of declining low cloud cover, no meaningful role for atmospheric CO2 concentration is possible and that therefore, the correlation between low cloud cover and surface temperature proves the falsehood of AGW theory. In this post, we test this KM2019 hypothesis that by comparing the relationship between atmospheric CO2 and global mean surface temperature below low clouds (HadCRUT4 surface temperature) with the corresponding relationship between atmospheric CO2 and global mean temperatures in the lower troposphere above low clouds (UAH). The study period is constrained to 1979-2018 by the availability of UAH satellite data for lower troposphere temperatures.
  6. The results are displayed in Figure 4 and Figure 5 above. Figure 4 displays the rate of warming in the study period for each calendar month labeled 1=January to 12=December along with the strength of the regression in terms of the T-statistic for both the surface temperature below low clouds (HAD) and the lower troposphere temperature (UAH) above low clouds. The warming rate is seen to be much stronger under low clouds than above low clouds. This result is consistent with the low cloud effect assumed in the KM2019 paper.
  7. The further conclusion in KM2019  that the observed warming during a time of decreasing low cloud cover proves the CO2 effect in AGW to be false is tested in Figure 5. If this KM2019 finding is correct, we would expect to find that temperatures below low clouds (HAD) would be relatively unrelated to atmospheric CO2 concentration but that temperatures above low clouds (UAH) would show a stronger correlation. What we see in Figure 5, however, is the exact opposite. Correlation of surface temperature below low clouds have a stronger correlation with Ln(CO2) {the natural logarithm of atmospheric CO2 concentration} than do lower troposphere temperatures above low clouds. In case of detrended correlations, though all values are generally very low, values above DETCORR=0.2 are statistically significant and are found only in the HAD surface temperatures below low clouds. These data are inconsistent with the KM2019 finding that the warming trend during a time of declining low cloud cover proves CO2 forcing of surface temperature to be false.
  8. An additional consideration is that cloud albedo is not just in low clouds but also from high clouds that have the greater cooling effect along with stratospheric aerosols. No declining trend in high clouds is evident in the data (Figure 2) that appear to show only cyclical variations. In light of these considerations, the emphasis on low clouds in the KM2019 analysis appears to be a form of data selection bias.
  9. CONCLUSION: The data show that the relationship between measures of AGW and low cloud cover is more complicated than implied by the KM2019  paper and that the correlation of warming above and below low clouds with atmospheric CO2 concentration are inconsistent with the interpretation of the data in the KM2019 study. As a reference, the cloud page in the climate4You blog [LINK] may contain more useful information on the interpretation of ISSCP cloud cover data than the relatively simplistic analysis contained in KM2019. Atmospheric water vapor content, low clouds, high clouds, and their combined surface temperature effects are more complicated and these effects vary regionally.

FIGURE 1: EL NINO AND LA NINA CYCLES (ENSO): DATA PROVIDED BY JAN NULL, METEOROLOGIST, GOLDEN GATE WEATHER SERVICES, A RECOGNIZED SOURCE OF ENSO INFORMATION[LINK]elnino4

bandicam 2019-07-03 11-47-06-708

bandicam 2019-07-03 11-48-49-549

 

FIGURE 2: TREND ANALYSIS OF OCEANIC NINO INDEX 1950-2019oni-gifTREND-ANALYSIS-TABLE

 

FIGURE 3: CORRELATION BETWEEN ONI AND TEMPERATUREONITEMP-GIF

 

FIGURE 4: CORRELATION ANALYSIS: JJA-MAJJJAMAJ-1JJAMAJ-2

 

FIGURE 5: CORRELATION ANALYSIS NDJ-MAJNDJMAJ-1

NDJMAJ-2

 

FIGURE 6: THE GEOLOGICAL SOURCE OF ENSO EVENTSelnino-1

ELNINO2

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THIS POST IS A CRITICAL REVIEW OF THE CLAIM BY CLIMATE SCIENCE THAT AGW CLIMATE CHANGE HAS MADE THE EL NINO – LA NINA ENSO CYCLE MORE INTENSE.

  1. THE SOURCE STUDY BY GROTHE & COBB of the Georgia Institute of Technology’s School of Earth and Atmospheric Sciences: Grothe, Pamela R., et al. “Enhanced El Niño‐Southern Oscillation variability in recent decades.” Geophysical Research Letters, 2019}  Abstract: The El Niño‐Southern Oscillation (ENSO) represents the largest source of year‐to‐year global climate variability. While earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of pre-industrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here, we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in spring/fall precessional insolation. We find that ENSO variability over the last five decades is ~25% stronger than during the preindustrial. Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing. 
  2. The authors have kindly provided a translation of their scientific language into plain English as follows: Our climate models tell us that El Niño will intensify due to greenhouse warming. Here, new coral reconstructions of the El Niño‐Southern Oscillation (ENSO) record show sustained, significant changes in ENSO variability over the last 7,000yrs, and at the same time we have found ENSO extremes over the last 50 years that are stronger than ENSO cycles of pre-industrial times.These results tell us that El Niño events are intensifying due to anthropogenic climate change. Key Point: (1) Data from Line Island corals show ENSO strength significantly weaker between 3,000 and 5,000 years ago compared to the 2,000‐year ago. (2) ENSO extremes of the last 50 years are significantly stronger than those of the pre‐industrial era in the central tropical Pacific. (3) Therefore, AGW climate change is causing ENSO cycles to become more extreme.
  3. A further translation into plain language has been kindly provided by Sci-Tech-Daily online magazine [LINK] as follows: Compelling Hard Evidence: El Nino Swings More Violently in the Industrial Age: El Ninos have become more intense in the industrial age, which stands to worsen storms, drought, and coral bleaching in El Nino years. A new study has found compelling evidence in the Pacific Ocean that the stronger El Ninos are part of a climate pattern that is new and strange.It is the first known time that enough physical evidence spanning millennia has come together to allow researchers to say definitively that: El Ninos, La Ninas, and the climate phenomenon that drives them have become more extreme in the times of human-induced climate change. The industrial age ENSO swings are 25% stronger than in the pre-industrial records. The evidence had slumbered in and around shallow Pacific waters, where ENSO and El Ninos originate. The corals’ recordings of sea surface temperatures proved to be astonishingly accurate when bench-marked. Coral records from 1981 to 2015 matched sea surface temperatures measured via satellite in the same period exactly. In 2018, enough coral data had amassed to distinguish ENSO’s recent activity from its natural pre-industrial patterns. To stress-test the data, Grothe left out chunks to see if the industrial age ENSO signal still stuck out. She removed the record-setting 1997/1998 El Nino-La Nina and examined industrial age windows of time between 30 and 100 years long. The signal held in all windows, but the data needed the 97/98 event to be statistically significant. This could mean that changes in the ENSO activities have just now reached a threshold that makes the impact of the industrial economy detectable.

 

 

RESPONSE AND CRITICAL COMMENTS ON THESE REPORTS

  1. The ENSO data in the form of the Oceanic Nino Index (ONI) published by Jan Null [LINK]  is displayed in Figure 1. As of this writing, the data cover a 70-year time period from 1950 to 2019 and present the ONI data for a moving 3-month window. The period since 1950 {“mid century”} is claimed by NASA and also by climate scientists in general  to be one in which the theory of AGW in terms of CO2 forcing of surface temperature is most apparent [LINK] . Therefore, if there is an impact of AGW CO2 forcing of surface temperature on ENSO strength, it should be apparent in an analysis of the relevant trends and correlations with respect to the ONI (Oceanic Nino Index) and temperature.
  2. Trends in the 3-month running average of the Oceanic Nino Index are displayed graphically in Figure 2. The top frame of Figure 2 is a GIF animation that cycles through the ten 3-month moving average values of the ONI from June-July-Aug to April-May-June of the following year. The study period in these charts is 1950-2019. The red line through the data in these charts is a 3rd order polynomial regression line that should show the trends as well as changes if any in the trend midstream. These lines appear to be rather flat without any kind of trend information being apparent in the graphical representation.
  3. The bottom frame of Figure 2 presents the results of linear regression trend analysis of the ONI against time from 1950 to 2019. No evidence of a trend in the ONI is found in the data. This finding is inconsistent with the proposition that AGW climate change has caused an increase in El Nino strength. The mechanism of this change is assumed to be rising sea surface temperatures (SST) attributed to CO2 forcing of AGW climate change. A more direct analysis of this relationship is presented with correlation analysis presented in Figure 3, Figure 4, and Figure 5.
  4. The top frame of Figure 3 is a GIF animation that cycles through the six regions studied (global, northern hemisphere, southern hemisphere, northern extent, southern extent, and tropics. The graphic shows that the temperature above oceans in the tropics shows the strongest correlations. The somewhat weaker correlations found for the two hemispheres vanish when the tropical portion of the hemisphere is removed to define the northern and southern extents. The ordinate contains the ten three-month periods for which the mean ONI and temperature data are used in the correlation analysis. They are 1=June-July-August to 10=March-April-May.  The highest correlations are seen for the winter months along with late fall and early spring.
  5. Thus, we find that detrended correlation analysis shows a strong correlation between UAH lower troposphere temperature above ocean areas and ONI. The correlation supports a relationship between temperature and ONI. This correlation is strongest for temperatures above the tropics (TR). Statistically significant correlations are also seen for temperatures for the Northern and Southern Hemispheres (NH & SH) but these correlations disappear when the Tropical section of the hemisphere is removed in the hemispheric region being studied (NX & SX).
  6. These results suggest that there is a temperature phenomenon in the tropics that causes rising and falling ONI levels even in the absence of a trend. A rational explanation for this relationship is found in the geology of the tropical region near the Solomon Islands and Papua New Guinea as shown in Figure 6. A detailed description of this localized geological source of the energy that drives the ENSO variability is described in a related post [LINK] .
  7. We conclude from the results of the trend analysis and detrended correlation analysis presented above that the data do not support the hypothesis that AGW temperature trends since 1950 have caused ENSO intensity to increase. If that were so there would be a trend and that trend would show a strong correlation with temperature that is not restricted to the tropics. The Temperature trend above the tropics attributed to AGW for the ten 3-month means in the Jan Null analysis presented in Figure 7 below do not show an AGW forcing behavior. More importantly, the ONI does not show a rising trend. The data are consistent with the evaluation in a related post that ENSO variability is driven by geological forces rather than by atmospheric composition. 

 

FIGURE 7:  TROPICAL OCEAN TEMPERATURE AND ONI TRENDStemp-oni-trends

 

 

ENSO VARIABILITY BIBLIOGRAPHY

  1. Yeh, Sang-Wook, et al. “El Niño in a changing climate.” Nature 461.7263 (2009): 511.  El Niño events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Niño events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies1,2,3,4,5 show that the canonical El Niño has become less frequent and that a different kind of El Niño has become more common during the late twentieth century, in which warm sea surface temperatures (SSTs) in the central Pacific are flanked on the east and west by cooler SSTs. This type of El Niño, termed the central Pacific El Niño (CP-El Niño; also termed the dateline El Niño2, El Niño Modoki3 or warm pool El Niño5), differs from the canonical eastern Pacific El Niño (EP-El Niño) in both the location of maximum SST anomalies and tropical–midlatitude teleconnections. Here we show changes in the ratio of CP-El Niño to EP-El Niño under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set6. Using calculations based on historical El Niño indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Niño compared to the EP-El Niño. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Niño to EP-El Niño, the occurrence ratio of CP-El Niño/EP-El Niño is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
  2. Timmermann, Axel, et al. “El Niño–southern oscillation complexity.” Nature 559.7715 (2018): 535-545.  El Niño events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Niño and cold La Niña conditions, referred to as the El Niño–Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system.
  3. Grothe, Pamela R., et al. “Enhanced El Niño‐Southern Oscillation variability in recent decades.” Geophysical Research Letters (2019).  The El Niño‐Southern Oscillation (ENSO) represents the largest source of year‐to‐year global climate variability. While earth system models suggest a range of possible shifts in ENSO properties under continued greenhouse gas forcing, many centuries of preindustrial climate data are required to detect a potential shift in the properties of recent ENSO extremes. Here, we reconstruct the strength of ENSO variations over the last 7,000 years with a new ensemble of fossil coral oxygen isotope records from the Line Islands, located in the central equatorial Pacific. The corals document a significant decrease in ENSO variance of ~20% from 3,000 to 5,000 years ago, coinciding with changes in spring/fall precessional insolation. We find that ENSO variability over the last five decades is ~25% stronger than during the preindustrial. Our results provide empirical support for recent climate model projections showing an intensification of ENSO extremes under greenhouse forcing.

 

 

FIGURE 1: THE ARCTIC AS SEEN FROM ABOVE THE NORTH POLE

svalbard-1

Figure 1 above is a map of the Arctic Ocean as seen from a point in space directly above the North Pole. From the North Pole, all directions are South. The Chuckhi Sea appears at the top of the map directly North of Beringia where Siberia meets Alaska. The Chukchi Sea is wedged in between Alaska and the Chukchi Peninsula of Siberia and extends as far North as Wrangel island. A close up of the Chukchi Sea area in a normal map where North is up and South is down is shown the two maps in Figure 2 below.

 

FIGURE 2: MAP OF THE CHUKCHI SEA

THIS POST IS A REVIEW OF A GIZMODO ARTICLE BY BRIAN KAHN [LINK TO TEXT] [LINK TO THE YOUTUBE VIDEO]  ON THE ODDITIES OF SEA ICE IN THE CHUKCHI SEA AND THE INTERPRETATION OF THESE ODDITIES IN TERMS OF AGW CLIMATE CHANGE AND ITS FEEDBACK AMPLIFICATION BY WAY OF LOST ALBEDO IN THE DECLINE OF SEA ICE EXTENT. THE FULL TEXT OF THE BRIAN KAHN ARTICLE IS INCLUDED BELOW AT THE END OF THIS PRESENTATION.  WITH BIBLIOGRAPHIC REFERENCES TO RESEARCH PAPERS ON SEA ICE EXTENT IN THE CONTEXT OF AGW.  

 

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FIGURE 3: THE ZACK LABE SEA ICE CHART

ZACKLABE

 

THE BRIAN KAHN ARTICLE ABOUT THE ZACK LABE SEA ICE CHART: 

CLIMATE CHANGE: Some Arctic Sea Ice Is Acting Like It’s Mid-Summer

  1. Winter has extended its grip on the Arctic, dropping a curtain of darkness on the top of the world. But at least one part of the Arctic is resisting its grasp. In what’s becoming an unfortunately common story, seasonal sea ice growth is stalling out in one of the gateway seas leading to the heart of the Arctic Ocean. The Chukchi Sea currently has a sea ice extent more reminiscent of summer than early winter, a sign that something is not right in the waters at the highest latitudes of the globe.

  2. The Chukchi Sea sits between northern Alaska and Russia. That makes it a crucial bridge to the Bering Sea, a place for sea to latch on and spread its icy tendrils to the south. But this winter so far has seen ice suffer. After bottoming out in September, the ice in the Chukchi Sea has failed to rebound. Usually, the dip in temperatures coupled with the lack of sunlight causes ice to build back up quickly. This year, though, growth has been much slower. Sea ice data crunched by University of California, Irvine PhD candidate and Arctic watcher Zack Labe shows that sea ice extent in the Chukchi Sea is the lowest on record for this time of year by a long shot.
  3. Arctic sea ice as a whole sits at its third lowest extent on record for this time of year and is well below the long-term average. Part of the reason for the sluggish growth ties to this spring and summer of sweltering discontent. Temperatures were abnormally high much too often. It reached nearly 95 degrees Fahrenheit in the Swedish Arctic. 
  4. Lightning, which generally requires warm, humid conditions, struck near the North Pole.  The northernmost settlement on Earth hit 70 degrees Fahrenheit for the first time ever. That’s just a smattering of all the ways the Arctic was fucked this summer. 
  5. Don’t even get me started on the fires, but they all point to the culprit likely driving weak sea ice growth: heat, and lots of it. The intense heat this summer helped melt ice. This year’s Arctic sea ice minimum was the second lowest on record. That in turn meant more dark, open water was available to absorb the suns rays and heat up itself. So even now that the sun has gone down for much of the Arctic, the last rays of summer are still very much present in the form of toasty (by Arctic standards) waters and making it hard for sea ice to form.
  6. This feedback loop is one of the hallmarks of climate change. Carbon pollution has warmed the Arctic twice as fast as the rest of the world, and the system has rapidly destabilized in recent years. The more plentiful fires and melting permafrost are releasing more carbon that will further speed up the changes. Meanwhile, disappearing sea ice and thus more open water will ensure the region continues to heat faster than the rest of the world. The vicious cycle has put the Arctic on the brink of a tipping point into a more volatile state unrecognizable from the Arctic we know today. If you want to know what the transition could look like, the Chukchi Sea is offering quite the lesson right now.

 

 

COMMENT ON THE BRIAN KAHN ARTICLE

It is noted and acknowledged by the authors (Zack Labe and Brian Kahn) that the sea ice phenomenon in question cannot be generalized to the Arctic Sea nor across the time span and time scale of AGW climate change that relates to long term trends in atmospheric heat balance. The event is localized to the Chukchi Sea, a small corner of the Arctic wedged in between Alaska and Siberia. The phenomenon is also time constrained to a singular event in time. A more rational explanation for this event than atmospheric heat energy trends since pre-industrial times is proposed in terms of the known geological features of the Chukchi Sea presented in the charts in Figure 4 below that include the Graben and Laptev rift systems. Anomalous events constrained by time and geography may not have a ready explanation in terms of long term atmospheric trends. It is shown in related posts that year to year changes in September minimum sea ice extent are unrelated to atmospheric temperature trends attributed to AGW climate change [LINK] [LINK] [LINK] . We therefore propose that Arctic sea ice dynamics should be understood not exclusively in terms of atmospheric phenomena but that their study should include effects of known geological dynamics of the Arctic particularly so when the the sea ice event in question is localized in time and space [LINK] [LINK] .

 

FIGURE 4: GEOLOGICAL FEATURES OF THE CHUKCHI SEA

TECTONIC-FEATURES-AMERASIA-BASIN

TECTONIC FEATURES OF THE AMERASIA BASIN: (KONONOV 2013): In the bottom frame of Figure 4 above, the black circles are the points of the heat flux measurements, and the digits in the circles are the average heat flux values. The straight lines are the magnetic anomalies. The double arrows denote the Aptian–Albian sublatitudinal extension of the Eurasian margin. The dashed line delineates the central block of the Arctida continent, which was fragmented as a result of rifting and diffuse spreading into the provinces of basins and ridges. Bathymetry simulation indicates that the Mesozoic Arctic Plume is in the lithosphere of the Alpha-Mendeleev and Lomonosov ridges (map above). The study also presents a model of the thermal subsidence to the asthenosphere. The calculated coefficients are compared with those obtained for the Greenland-Iceland and Iceland-Faeroe ridges, which were formed in response to hotspot activity. It was shown that the coefficients of the thermal subsidence in the central part of the Alpha-Mendeleev and Lomonosov Ridges are similar to those calculated for the Greenland-Iceland and Iceland-Faeroe ridges. This indicates the thermal regime of the subsidence of the Alpha-Mendeleev and Lomonosov ridges since the Early Miocene and the increased influence of the Arctic plume on the ridge genesis.

 

 

CHUKCHI SEA SEA-ICE BIBLIOGRAPHY 

 

  1. Neal, Victor T., Stephen Neshyba, and Warren Denner. “Thermal stratification in the Arctic Ocean.” Science 166.3903 (1969): 373-374.  Fine scale measurements of the vertical temperature profile in an Arctic water column show the presence of several cascaded isothermal layers. Layers between the depths of 300 anid 350 meters range from 2 to 10 meters in thickness, while the temperature change between adjacent layers is approximately 0.026°C. The individual layers are isothermal to within ± 0.001°C.
  2. Van, Hulsen A. “Geothermal channel and harbor ice control system.” U.S. Patent No. 3,807,491. 30 Apr. 1974A thermo-arctic sea passage is formed and maintained by providing a series of geothermal wells spaced along the intended route. Heat energy transferred from a deep geothermal strata to the surface melts the ice to form a water channel. Reformation of ice is inhibited by efficient and active water movement and wave action induced by wind action.
  3. von Quillfeldt, Cecilie H., William G. Ambrose, and Lisa M. Clough. “High number of diatom species in first-year ice from the Chukchi Sea.” Polar Biology 26.12 (2003): 806-818.  Our study describes the species composition of microalgae, primarily diatoms, in two ice cores collected from the Chukchi Sea in early June 1998. At least 251 species were present in 2 cores collected 10 m apart in first-year ice. This is a greater number of algal species in ice from one locality than has been recorded from any other area of the Arctic. Microalgae were distributed throughout the 173-cm-long core, but abundance and species composition varied among different sections of the core, with maximum species richness (108 and 103 species in the 94- to 103- and 103- to 113-cm sections, respectively) occurring in the middle sections. More than 237 species were recorded from this core. Only the bottom 20 cm of the shorter (110 cm) core was analysed and it contained 135 algal species, still an extraordinarily high number of species. Marine species dominated both cores, but typical brackish and freshwater species were also present. None of these species, however, had more than 1% relative abundance. It should be noted, though, that there were several distinct, but unidentified, species of unknown origin. Characteristic ice algal species (e.g. Nitzschia frigida, Navicula pelagica, solitary Navicula spp., in addition to Cylindrotheca closterium) were the numerical dominants in most sections of the long core, but phytoplankton and benthic species were quite abundant in some sections. One section was dominated by a blue-green bacterium, presumably of the genus Anabaena. The species composition is consistent with several different mechanisms for algal incorporation into ice (i.e. seawater filtration ice, seeding from the sea floor, freshwater input). Over time, ice dynamics and sources of ice in the Chukchi Sea appear to result in high numbers of algal species in the ice. It is also likely that season of collection contributed to the high number of species observed. Determining the geographical area of origin for the different species is however difficult, due to the large-scale pattern of ice circulation.
  4. Martin, Seelye, et al. “Estimation of the thin ice thickness and heat flux for the Chukchi Sea Alaskan coast polynya from Special Sensor Microwave/Imager data, 1990–2001.” Journal of Geophysical Research: Oceans 109.C10 (2004).  One of the largest Arctic polynyas occurs along the Alaskan coast of the Chukchi Sea between Cape Lisburne and Point Barrow. For this polynya (iceless sea surface surrounded by sea ice), a new thin ice thickness algorithm is described that uses the ratio of the vertically and horizontally polarized Special Sensor Microwave/Imager (SSM/I) 37‐GHz channels to retrieve the distribution of thicknesses and heat fluxes at a 25‐km resolution. Comparison with clear‐sky advanced very high resolution radiometer data shows that the SSM/I thicknesses and heat fluxes are valid for ice thicknesses less than 10–20 cm, and comparison with several synthetic aperture radar (SAR) images shows that the 10‐cm ice SSM/I ice thickness contour approximately follows the SAR polynya edge. For the twelve winters of 1990–2001, the ice thicknesses and heat fluxes within the polynya are estimated from daily SSM/I data, then compared with field data and with estimates from other investigations. The results show the following: First, our calculated heat losses are consistent with 2 years of over‐winter salinity and temperature field data. Second, comparison with other numerical and satellite estimates of the ice production shows that although our ice production per unit area is smaller, our polynya areas are larger, so that our ice production estimates are of the same order. Because our salinity forcing occurs over a larger area than in the other models, the oceanic response associated with our forcing will be modified.
  5. De Vernal, Anne, Claude Hillaire‐Marcel, and Dennis A. Darby. “Variability of sea ice cover in the Chukchi Sea (western Arctic Ocean) during the Holocene.” Paleoceanography 20.4 (2005).  Dinocysts from cores collected in the Chukchi Sea from the shelf edge to the lower slope were used to reconstruct changes in sea surface conditions and sea ice cover using modern analogue techniques. Holocene sequences have been recovered in a down‐slope core (B15: 2135 m, 75°44′N, sedimentation rate of ∼1 cm kyr−1) and in a shelf core (P1: 201 m, 73°41′N, sedimentation rate of ∼22 cm kyr−1). The shelf record spanning about 8000 years suggests high‐frequency centennial oscillations of sea surface conditions and a significant reduction of the sea ice at circa 6000 and 2500 calendar (cal) years B.P. The condensed offshore record (B15) reveals an early postglacial optimum with minimum sea ice cover prior to 12,000 cal years B.P., which corresponds to a terrestrial climate optimum in Bering Sea area. Dinocyst data indicate extensive sea ice cover (>10 months yr−1) from 12,000 to 6000 cal years B.P. followed by a general trend of decreasing sea ice and increasing sea surface salinity conditions, superimposed on large‐amplitude millennial‐scale oscillations. In contrast, δ18O data in mesopelagic foraminifers (Neogloboquadrina pachyderma) and benthic foraminifers (Cibicides wuellerstorfi) reveal maximum subsurface temperature and thus maximum inflow of the North Atlantic water around 8000 cal years B.P., followed by a trend toward cooling of the subsurface to bottom water masses. Sea‐surface to subsurface conditions estimated from dinocysts and δ18O data in foraminifers thus suggest a decoupling between the surface water layer and the intermediate North Atlantic water mass with the existence of a sharp halocline and a reverse thermocline, especially before 6000 years B.P. The overall data and sea ice reconstructions from core B15 are consistent with strong sea ice convergence in the western Arctic during the early Holocene as suggested on the basis of climate model experiments including sea ice dynamics, matching a higher inflow rate of North Atlantic Water.
  6. Björk, Göran, and Peter Winsor. “The deep waters of the Eurasian Basin, Arctic Ocean: Geothermal heat flow, mixing and renewal.” Deep Sea Research Part I: Oceanographic Research Papers 53.7 (2006): 1253-1271.  Hydrographic observations from four separate expeditions to the Eurasian Basin of the Arctic Ocean between 1991 and 2001 show a 300–700 m thick homogenous bottom layer. The layer is characterized by slightly warmer temperature compared to ambient, overlying water masses, with a mean layer thickness of 500±100 m and a temperature surplus of 7.0±2×10−3 °C. The layer is present in the deep central parts of the Nansen and Amundsen Basins away from continental slopes and ocean ridges and is spatially coherent across the interior parts of the deep basins. Here we show that the layer is most likely formed by convection induced by geothermal heat supplied from Earth’s interior. Data from 1991 to 1996 indicate that the layer was in a quasi steady state where the geothermal heat supply was balanced by heat exchange with a colder boundary. After 1996 there is evidence of a reformation of the layer in the Amundsen Basin after a water exchange. Simple numerical calculations show that it is possible to generate a layer similar to the one observed in 2001 in 4–5 years, starting from initial profiles with no warm homogeneous bottom layer. Limited hydrographic observations from 2001 indicate that the entire deep-water column in the Amundsen Basin is warmer compared to earlier years. We argue that this is due to a major deep-water renewal that occurred between 1996 and 2001.
  7. Francis, Jennifer A., and Elias Hunter. “New insight into the disappearing Arctic sea ice.” Eos, Transactions American Geophysical Union 87.46 (2006): 509-511. The dramatic loss of Arctic sea ice is ringing alarm bells in the minds of climate scientists, policy makers, and the public. The extent of perennial sea ice—ice that has survived a summer melt season—has declined 20% since the mid‐1970s [Stroeue et al., 2005]. Its retreat varies regionally, driven by changes in winds and heating from the atmosphere and oceanLimited data have hampered attempts to identify which culprits are to blame, but new satellite‐derived information provides insight into the drivers of change. A clear message emerges. The location of the summer ice edge is strongly correlated to variability in longwave (infrared) energy emitted by the atmosphere (downward longwave flux; DLF), particularly during the most recent decade when losses have been most rapid. Increasing DLF, in turn, appears to be driven by more clouds and water vapor in spring over the Arctic.
  8. McKay, J. L., et al. “Holocene fluctuations in Arctic sea-ice cover: dinocyst-based reconstructions for the eastern Chukchi Sea.” Canadian Journal of Earth Sciences 45.11 (2008): 1377-1397.  Cores from site HLY0501-05 on the Alaskan margin in the eastern Chukchi Sea were analyzed for their geochemical (organic carbon, δ13Corg, Corg/N, and CaCO3) and palynological (dinocyst, pollen, and spores) content to document oceanographic changes during the Holocene. The chronology of the cores was established from 210Pb dating of near-surface sediments and 14C dating of bivalve shells. The sediments span the last 9000 years, possibly more, but with a gap between the base of the trigger core and top of the piston core. Sedimentation rates are very high (∼156 cm/ka), allowing analyses with a decadal to centennial resolution. The data suggest a shift from a dominantly terrigenous to marine input from the early to late Holocene. Dinocyst assemblages are characterized by relatively high concentrations (600–7200 cysts/cm3) and high species diversity, allowing the use of the modern analogue technique for the reconstruction of sea-ice cover, summer temperature, and salinity. Results indicate a decrease in sea-ice cover and a corresponding, albeit much smaller, increase in summer sea-surface temperature over the past 9000 years. Superimposed on these long-term trends are millennial-scale fluctuations characterized by periods of low sea-ice and high sea-surface temperature and salinity that appear quasi-cyclic with a frequency of about one every 2500–3000 years. The results of this study clearly show that sea-ice cover in the western Arctic Ocean has varied throughout the Holocene. More importantly, there have been times when sea-ice cover was less extensive than at the end of the 20th century.
  9. Grebmeier, Jacqueline M., et al. “Biological response to recent Pacific Arctic sea ice retreats.” Eos, Transactions American Geophysical Union 91.18 (2010): 161-162.  Although recent major changes in the physical domain of the Arctic region, such as extreme retreats of summer sea ice since 2007, are well documented, large uncertainties remain regarding responses in the biological domain. In the Pacific Arctic north of Bering Strait, reduction in sea ice extent has been seasonally asymmetric, with minimal changes until the end of June and delayed sea ice formation in late autumn. The effect of extreme ice retreats and seasonal asymmetry in sea ice loss on primary production is uncertain, with no clear shift over time (2003–2008) in satellite‐derived chlorophyll concentrations. However, clear changes have occurred during summer in species ranges for zooplankton, bottom‐dwelling organisms (benthos), and fish, as well as through the loss of sea ice as habitat and platform for marine mammals.
  10. Nicolsky, D., and N. Shakhova. “Modeling sub-sea permafrost in the East Siberian Arctic Shelf: the Dmitry Laptev Strait.” Environmental Research Letters 5.1 (2010): 015006The present state of sub-sea permafrost modeling does not agree with certain observational data on the permafrost state within the East Siberian Arctic Shelf. This suggests a need to consider other mechanisms of permafrost destabilization after the recent ocean transgression. We propose development of open taliks wherever thaw lakes and river paleo-valleys were submerged shelf-wide as a possible mechanism for the degradation of sub-sea permafrost. To test the hypothesis we performed numerical modeling of permafrost dynamics in the Dmitry Laptev Strait area. We achieved sufficient agreement with the observed distribution of thawed and frozen layers to suggest that the proposed mechanism of permafrost destabilization is plausible. Two basic mechanisms are proposed to explain permafrost dynamics after the inundation: the so-called upward degradation under geothermal heat flux in the areas underlain by fault zones (Romanovskii and Hubberten 2001), and the so-called downward degradation under the warming effect of large river bodies (Delisle 2000).
  11. Douglas, David C. Arctic sea ice decline: projected changes in timing and extent of sea ice in the Bering and Chukchi Seas. No. 2010-1176. US Geological Survey, 2010 The Arctic region is warming faster than most regions of the world due in part to increasing greenhouse gases and positive feedbacks associated with the loss of snow and ice cover. One consequence has been a rapid decline in Arctic sea ice over the past 3 decades?a decline that is projected to continue by state-of-the-art models. Many stakeholders are therefore interested in how global warming may change the timing and extent of sea ice Arctic-wide, and for specific regions. To inform the public and decision makers of anticipated environmental changes, scientists are striving to better understand how sea ice influences ecosystem structure, local weather, and global climate. Here, projected changes in the Bering and Chukchi Seas are examined because sea ice influences the presence of, or accessibility to, a variety of local resources of commercial and cultural value. In this study, 21st century sea ice conditions in the Bering and Chukchi Seas are based on projections by 18 general circulation models (GCMs) prepared for the fourth reporting period by the Intergovernmental Panel on Climate Change (IPCC) in 2007. Sea ice projections are analyzed for each of two IPCC greenhouse gas forcing scenarios: the A1B `business as usual? scenario and the A2 scenario that is somewhat more aggressive in its CO2 emissions during the second half of the century. A large spread of uncertainty among projections by all 18 models was constrained by creating model subsets that excluded GCMs that poorly simulated the 1979-2008 satellite record of ice extent and seasonality. At the end of the 21st century (2090-2099), median sea ice projections among all combinations of model ensemble and forcing scenario were qualitatively similar. June is projected to experience the least amount of sea ice loss among all months. For the Chukchi Sea, projections show extensive ice melt during July and ice-free conditions during August, September, and October by the end of the century, with high agreement among models. High agreement also accompanies projections that the Chukchi Sea will be completely ice covered during February, March, and April at the end of the century. Large uncertainties, however, are associated with the timing and amount of partial ice cover during the intervening periods of melt and freeze. For the Bering Sea, median March ice extent is projected to be about 25 percent less than the 1979-1988 average by mid-century and 60 percent less by the end of the century. The ice-free season in the Bering Sea is projected to increase from its contemporary average of 5.5 months to a median of about 8.5 months by the end of the century. A 3-month longer ice- free season in the Bering Sea is attained by a 1-month advance in melt and a 2-month delay in freeze, meaning the ice edge typically will pass through the Bering Strait in May and January at the end of the century rather than June and November as presently observed.
  12. Carmack, Eddy C., et al. “The Arctic Ocean warms from below.” Geophysical Research Letters 39.7 (2012).  The old (∼450‐year isolation age) and near‐homogenous deep waters of the Canada Basin (CBDW), that are found below ∼2700 m, warmed at a rate of ∼0.0004°C yr−1 between 1993 and 2010. This rate is slightly less than expected from the reported geothermal heat flux (Fg ∼ 50 mW m−2). A deep temperature minimum Tmin layer overlies CBDW within the basin and is also warming at approximately the same rate, suggesting that some geothermal heat escapes vertically through a multi‐stepped, ∼300‐m‐thick deep transitional layer. Double diffusive convection and thermobaric instabilities are identified as possible mechanisms governing this vertical heat transfer. The CBDW found above the lower continental slope of the deep basin maintains higher temperatures than those in the basin interior, consistent with geothermal heat being distributed through a shallower water column, and suggests that heat from the basin interior does not diffuse laterally and escape at the edges.
  13. Jay, Chadwick V., Anthony S. Fischbach, and Anatoly A. Kochnev. “Walrus areas of use in the Chukchi Sea during sparse sea ice cover.” Marine Ecology Progress Series 468 (2012): 1-13. The Pacific walrus Odobenus rosmarus divergens feeds on benthic invertebrates on the continental shelf of the Chukchi and Bering Seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase further in frequency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea from June to November of 2008 to 2011, years when sea ice was sparse over the continental shelf in comparison to historical records. The earlier and more extensive sea ice retreat in June to September, and delayed freeze-up of sea ice in October to November, created conditions for walruses to arrive earlier and stay later in the Chukchi Sea than in the past. The lack of sea ice over the continental shelf from September to October caused walruses to forage in nearshore areas instead of offshore areas as in the past. Walruses did not frequent the deep waters of the Arctic Basin when sea ice retreated off the shelf. Walruses foraged in most areas they occupied, and areas of concentrated foraging generally corresponded to regions of high benthic biomass, such as in the northeastern (Hanna Shoal) and southwestern Chukchi Sea. A notable exception was the occurrence of concentrated foraging in a nearshore area of northwestern Alaska that is apparently depauperate in walrus prey. With increasing sea ice loss, it is likely that walruses will increase their use of coastal haul-outs and nearshore foraging areas, with consequences to the population that are yet to be understood.
  14. Arrigo, Kevin R., et al. “Massive phytoplankton blooms under Arctic sea ice.” Science 336.6087 (2012): 1408-1408Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.
  15. Arrigo, Kevin R., et al. “Phytoplankton blooms beneath the sea ice in the Chukchi Sea.” Deep Sea Research Part II: Topical Studies in Oceanography 105 (2014): 1-16.  In the Arctic Ocean, phytoplankton blooms on continental shelves are often limited by light availability, and are therefore thought to be restricted to waters free of sea ice. During July 2011 in the Chukchi Sea, a large phytoplankton bloom was observed beneath fully consolidated pack ice and extended from the ice edge to >100 km into the pack. The bloom was composed primarily of diatoms, with biomass reaching 1291 mg chlorophyll a m−2 and rates of carbon fixation as high as 3.7 g C m−2 d−1. Although the sea ice where the bloom was observed was near 100% concentration and 0.8–1.2 m thick, 30–40% of its surface was covered by melt ponds that transmitted 4-fold more light than adjacent areas of bare ice, providing sufficient light for phytoplankton to bloom. Phytoplankton growth rates associated with the under-ice bloom averaged 0.9 d−1 and were as high as 1.6 d−1. We argue that a thinning sea ice cover with more numerous melt ponds over the past decade has enhanced light penetration through the sea ice into the upper water column, favoring the development of these blooms. These observations, coupled with additional biogeochemical evidence, suggest that phytoplankton blooms are currently widespread on nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in waters where under-ice blooms develop are ~10-fold too low. These massive phytoplankton blooms represent a marked shift in our understanding of Arctic marine ecosystems.
  16. Carmack, Eddy, et al. “Toward quantifying the increasing role of oceanic heat in sea ice loss in the new Arctic.” Bulletin of the American Meteorological Society 96.12 (2015): 2079-2105.  The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with implications for governance, economics, security, and global weather. A wide range in model projections reflects the complex, highly coupled interactions between the polar atmosphere, ocean, and cryosphere, including teleconnections to lower latitudes. This paper summarizes our present understanding of how heat reaches the ice base from the original sources—inflows of Atlantic and Pacific Water, river discharge, and summer sensible heat and shortwave radiative fluxes at the ocean/ice surface—and speculates on how such processes may change in the new Arctic. The complexity of the coupled Arctic system, and the logistic and technological challenges of working in the Arctic Ocean, require a coordinated interdisciplinary and international program that will not only improve understanding of this critical component of global climate but will also provide opportunities to develop human resources with the skills required to tackle related problems in complex climate systems. We propose a research strategy with components that include 1) improved mapping of the upper- and middepth Arctic Ocean, 2) enhanced quantification of important process, 3) expanded long-term monitoring at key heat-flux locations, and 4) development of numerical capabilities that focus on parameterization of heat-flux mechanisms and their interactions.

 

 

 

 

 

 

 

 

 

 

Arctic Ocean could be ice-free for part of the year as soon as 2044

 

[LINK TO HOME PAGE OF THIS SITE]

 

THIS POST IS A REVIEW OF M.PHYS.ORG 2019 ARCTIC OCEAN ICE FREE [LINK] 

 

THE ARTICLE ABOUT THE PAPER AND ABSTRACT OF THE PAPER

  1. The fate of Arctic sea ice is a key topic for climate scientists because of its role in temperatures around the rest of the world. It’s hard to imagine the Arctic without sea ice. But according to a new study by UCLA climate scientists, human-caused climate change is on track to make the Arctic Ocean functionally ice-free for part of each year starting sometime between 2044 and 2067. 
  2. As long as humans have been on Earth, the planet has had a large cap of sea ice at the Arctic Circle that expands each winter and contracts each summer. The knowledge that sea ice is on the decline is not new: Satellite observations show that since 1979, the amount of sea ice in the Arctic in September—the month when there is the least sea ice, before water starts freezing again—has declined by 13 percent per decade.
  3. Scientists have been attempting to predict the future of Arctic sea ice for several decades, relying on an array of global climate models that simulate how the climate system will react to the carbon dioxide entering the atmosphere. But the models’ predictions have disagreed widely. Some show ice-free Septembers as early as 2026; others suggest the phenomenon will begin as late as 2132.
  4. The UCLA study, which was published in Nature Climate Change, narrows the predictions to a 25-year period. Sea ice loss diverge because they differ in how their estimation of sea ice loss albedo feedback is expected to cause greater local warming, which in turn leads to further ice melt. This feedback exacerbates warming and is one reason why the Arctic is heating up twice as fast as the rest of the globe.
  5. Thackeray and co-author Alex Hall, UCLA professor of atmospheric and oceanic sciences, determined which models are most realistic in sea ice albedo feedback estimation that would lead them to the most realistic projections for sea ice. They used the seasonal sea ice cycle to estimate the albedo feedback effect. Satellite observations track the seasonal melt cycle that includes the albedo feedback. Of 23 different climate models, the authors identified six models that were closest to the observational data in the period 1980-2015.
  6. The approach of using an observable process in the current climate to evaluate global climate model projections of future climate was pioneered by Hall and his group in 2006, in a study focused on snow albedo feedback. It has since become widely used in climate science as researchers try to improve the precision of their projections. The fate of Arctic sea ice is a key topic for climate scientists because of its global impact on temperature. “Arctic sea ice is a key component of the earth system because of its highly reflective nature, which keeps the global climate relatively cool“, Thackeray said.
  7. There are other environmental and economic implications to ice loss as well. Sea ice is critical to the Arctic ecosystem, and to the fishing industry and indigenous peoples who depend on that ecosystem. And as Arctic ice is lost, more waters are used for commercial shipping and oil and gas exploration, which presents economic opportunity for some nations, but which also contributes to further greenhouse gas emissions and climate change. “The changes to come will have broad environmental, ecological and economic implications,” Thackeray said. “By reducing the uncertainty in in our ice free prediction, we can be better prepared.”
  8. CITATION AND ABSTRACT: Thackeray, Chad W., and Alex Hall. “An emergent constraint on future Arctic sea-ice albedo feedback.” Nature Climate Change (2019): 1-7Arctic sea ice has decreased substantially over recent decades, a trend projected to continue. Shrinking ice reduces surface albedo, leading to greater surface solar absorption, thus amplifying warming and driving further melt. This sea-ice albedo feedback (SIAF) is a key driver of Arctic climate change and an important uncertainty source in climate model projections. Using an ensemble of models, we demonstrate an emergent relationship between future SIAF and an observable version of SIAF in the current climate’s seasonal cycle. This relationship is robust in constraining SIAF over the coming decades (Pearson’s r = 0.76), and then it degrades. The degradation occurs because some models begin producing ice-free conditions, signalling a transition to a new ice regime. The relationship is strengthened when models with unrealistically thin historical ice are excluded. Because of this tight relationship, reducing model errors in the current climate’s seasonal SIAF and ice thickness can narrow SIAF spread under climate change. 

 

 

A HISTORY OF FAILED ICE FREE ARCTIC FORECASTS

  1. 1999, STUDY SHOWS ARCTIC ICE SHRINKING BECAUSE OF GLOBAL WARMING. Sea ice in the Arctic Basin is shrinking by 14000 square miles per year because of global warming caused by human activity according to a new international study that used 46 years of data and sophisticated computer simulation models to tackle the specific question of whether the loss of Arctic ice is a natural variation or caused by global warming. The computer model says that the probability that these changes were caused by natural variation is 1% but when global warming was added to the model the ice melt was a perfect fit. Therefore the ice melt is caused by human activities that emit greenhouse gases.
  2. 2003, SOOT WORSE FOR GLOBAL WARMING THAN PREVIOUSLY THOUGHT
    Soot that lands on snow has caused ¼ of the warming since 1880 because dirty snow traps more solar heat than pristine snow and induces a strong warming effect, according to a new computer model by James Hansen of NASA. It explains why sea ice and glaciers are melting faster than they should. Reducing soot emissions is an effective tool to curb global warming. It is easier to cut soot emissions than it is to cut CO2 emissions but we still need to reduce CO2 emissions in order to stabilize the atmosphere.
  3. 2004, ARCTIC CLIMATE IMPACT ASSESSMENT
    An unprecedented 4-year study of the Arctic shows that polar bears, walruses, and some seals are becoming extinctArctic summer sea ice may disappear entirely. Combined with a rapidly melting Greenland ice sheet, it will raise the sea level 3 feet by 2100 inundating lowlands from Florida to Bangladesh. Average winter temperatures in Alaska and the rest of the Arctic are projected to rise an additional 7 to 13 degrees over the next 100 years because of increasing emissions of greenhouse gases from human activities. The area is warming twice as fast as anywhere else because of global air circulation patterns and natural feedback loops, such as less ice reflecting sunlight, leading to increased warming at ground level and more ice melt. Native peoples’ ways of life are threatened. Animal migration patterns have changed, and the thin sea ice and thawing tundra make it too dangerous for humans to hunt and travel.
  4. 2004, RAPID ARCTIC WARMING BRINGS SEA LEVEL RISE
    The Arctic Climate Impact Assessment (ACIA) report says: increasing greenhouse gases from human activities is causing the Arctic to warm twice as fast as the rest of the planet; in Alaska, western Canada, and eastern Russia winter temperatures have risen by 2C to 4C in the last 50 years; the Arctic will warm by 4C to 7C by 2100. A portion of Greenland’s ice sheet will melt; global sea levels will rise; global warming will intensify. Greenland contains enough melting ice to raise sea levels by 7 meters; Bangkok, Manila, Dhaka, Florida, Louisiana, and New Jersey are at risk of inundation; thawing permafrost and rising seas threaten Arctic coastal regions; climate change will accelerate and bring about profound ecological and social changes; the Arctic is experiencing the most rapid and severe climate change on earth and it’s going to get a lot worse; Arctic summer sea ice will decline by 50% to 100%polar bears will be driven towards extinction; this report is an urgent SOS for the Arctic; forest fires and insect infestations will increase in frequency and intensity; changing vegetation and rising sea levels will shrink the tundra to its lowest level in 21000 years; vanishing breeding areas for birds and grazing areas for animals will cause extinctions of many species; “if we limit emission of heat trapping carbon dioxide we can still help protect the Arctic and slow global warming”.
  5. 2007: THE ARCTIC IS SCREAMING
    Climate science declares that the low sea ice extent in the Arctic is the leading indicator of climate change. We are told that the Arctic “is screaming”, that Arctic sea ice extent is the “canary in the coal mine”, and that Polar Bears and other creatures in the Arctic are dying off and facing imminent extinction. Scientists say that the melting sea ice has set up a positive feedback system that would cause the summer melts in subsequent years to be greater and greater until the Arctic becomes ice free in the summer of 2012. We must take action immediately to cut carbon dioxide emissions from fossil fuels. [DETAILS] 
  6. 2007: THE ICE FREE ARCTIC CLAIMS GAIN MOMENTUM
    The unusual summer melt of Arctic sea ice in 2007 has encouraged climate science to warn the world that global warming will cause a steep decline in the amount of ice left in subsequent summer melts until the Arctic becomes ice free in summer and that could happen as soon as 2080 or maybe 2060 or it could even be 2030. This time table got shorter and shorter until, without a “scientific” explanation, the ice free year was brought up to 2013. In the meantime, the data showed that in 2008 and 2009 the summer melt did not progressively increase as predicted but did just the opposite by making a comeback in 2008 that got even stronger in 2009. [DETAILS]
  7. 2008: POSITIVE FEEDBACK: ARCTIC SEA ICE IN A DOWNWARD SPIRAL
    Our use of fossil fuels is devastating the Arctic where the volume of sea ice “fell to its lowest recorded level to date” this year and that reduced ice coverage is causing a non-linear acceleration in the loss of polar ice because there is less ice to reflect sunlight. [DETAILS]
  8. 2008: THE ARCTIC WILL BE ICE FREE IN SUMMER IN 2008, 2013, 2030, OR 2100
    The unusually low summer sea ice extent in the Arctic in 2007
    The IPCC has taken note and has revised its projection of an ice free Arctic first from 2008 to 2013 and then again from 2013 to 2030. The way things are going it may be revised again to the year 2100. [DETAILS]
  9. 2008: GLOBAL WARMING IS THE CAUSE OF ALL ICE MELT EVENTS
    When there was a greater focus on Antarctica climate scientists said that global warming was melting the West Antarctic Ice Shelf; but the melting was found to be localized and with an active volcano underneath the melting and the attention of “melt forecast” climate science shifted to Arctic sea ice after the an extensive summer melt was observed in September 2007. [DETAILS]
  10. 2008: THE POLAR BEAR IS THREATENED BY OUR USE OF FOSSIL FUELS
    The survival of the polar bear is threatened because man made global warming is melting ice in the Arctic. It is true that the Arctic sea ice extent was down in negative territory in September 2007. This event emboldened global warming scaremongers to declare it a climate change disaster caused by greenhouse gas emissions from fossil fuels and to issue a series of scenarios about environmental holocaust yet to come. [DETAILS]
  11. 2009: SUMMER ARCTIC SEA ICE EXTENT IN 2009 THE 3RD LOWEST ON RECORD
    The second lowest was 2008 and the first lowest was 2007. This is not a trend that shows that things are getting worse. It shows that things are getting better and yet it is being sold and being bought as evidence that things are getting worse due to rising fossil fuel emissions. [DETAILS]
  12. 2009: THE ARCTIC WILL BE ICE FREE IN SUMMER BY 2029
    An alarm is raised that the extreme summer melt of Arctic sea ice in 2007 was caused by humans using fossil fuels and it portends that in 20 years human caused global warming will leave the Arctic Ocean ice-free in the summer raising sea levels and harming wildlife. [DETAILS]
  13. 2009: THE ARCTIC WILL BE ICE FREE IN SUMMER BY THE YEAR 2012
    Climate scientists continue to extrapolate the extreme summer melt of Arctic sea ice in 2007 to claim that the summer melt of 2007 was a climate change event and that it implies that the Arctic will be ice free in the summer from 2012 onwards. This is a devastating effect on the planet and our use of fossil fuels is to blame. [DETAILS]
  14. 2009: THE SUMMER SEA ICE EXTENT IN THE ARCTIC WILL BE GONE
    Summer melt of Arctic ice was the third most extensive on record in 2009, second 2008, and the most extensive in 2007. These data show that warming due to our carbon dioxide emissions are causing summer Arctic ice to gradually diminish until it will be gone altogether. [DETAILS]

 

 

COMMENTS ON THE THESIS OF THE ARTICLE AND REFERENCE PAPER

  1. The premise of this paper is “Yes, there were a few ice-free-Arctic forecasts that didn’t happen but this time around we got the ice free forecast right because we tuned the climate model with the seasonal cycle“. This premise is supported by the claim that the climate models that were used to predict the ice free condition were pre-tested against the seasonal cycle and those climate models that could correctly predict the September minimum sea ice extent in the seasonal cycle were taken to be accurate predictors of long term trends in sea ice extent and these models were used to make the long term prediction of an ice free September. It is proposed that the long term forecast is validated by the ability of the same climate model to forecast the seasonal September minimum sea ice extent. Therefore the forecast of that validated climate model that the long awaited ice-free September will occur sometime between 2044 and 2067 {at some point 28 to 48 years from now} is is finally the correct forecast of an ice free Arctic. 
  2. This argument is flawed in a number of ways. First, the seasonal cycle in Arctic air temperature above the Ocean imposes a range of surface air temperatures equivalent to more than 70 years (range = 40 to 130 years) of warming at the current long term warming rate in September temperature of 0,026C per year (Figure 1). Also the regression for the trend contains large uncertainties (Figure 2) so that temperature forecasts contain large uncertainties regardless of the quality of the climate model (Figure 4). Note in Figure 3 that the regression residuals when expressed as multiples of the regression coefficient are in a range of -40 to +25 times the long term trend contained in the regression coefficient. Therefore, the seasonal cycle of the year and the year to year long term trend and very different phenomena such that the forecast for future years cannot be based on seasonal cycle dynamics. Uncertainties in year to year September temperature when compared with the predictable seasonal cycle imply that year to year surface air temperatures are not as exactly predictable as one might presume from the more predictable nature of the seasonal cycle.
  3. An added consideration in the frustration of climate science with ice free Arctic predictions is the atmosphere bias of climate science such that all ice melt events in the Arctic region are assumed to be governed by air temperature and by changes in air temperature without empirical evidence of this relationship. This overarching assumption of climate science derives from a reliance on climate models as we see in the Thackeray paper presented here. Yet it is not possible to use climate models in a test of theory because climate models are themselves an expression of theory. A lopsided reliance of climate science on climate models diminishes the role of observational data and and emphasizes theoretical considerations. This aberration in climate science is particularly severe in the case of their evaluation of sea ice dynamics.
  4. In related posts on this site it is shown that this assumption derived from climate models is not supported by the empirical data. Detrended correlation analysis does not provide the needed evidence in the form of a statistically significant negative correlation between temperature and sea ice extent that is a necessary condition for a causal relationship between surface air temperature and sea ice extent [LINK] [LINK] . Thus, no empirical evidence exists that Arctic sea ice extent is responsive to surface air temperature at an annual time scale and yet this responsiveness is assumed in the attribution of changes in Arctic sea ice extent to changes in surface air temperature.
  5. Yet another relevant consideration is that the Arctic is a known to be a geologically active region with large flows of geothermal heat from the mantle into the ocean. The continued attribution of sea ice dynamics whether in extent, area, or volume, to AGW climate change and without consideration for known geothermal heat flows likely derives from the atmosphere bias of climate science such that there is a tendency to explain all observed changes in the Arctic, such as sea ice melt, in terms of AGW climate change and to overlook the extensive geothermal heat sources in the Arctic. Some of the geological features of the Arctic including the Mid Arctic Rift system and the Jan Mayen Trend are described in related posts [LINK] [LINK] and in the Graphic in Figure 5. A detailed study of the geology of the Arctic is presented in a related post [LINK] .

 

FIGURE 1: SEASONAL RANGE AS MULTIPLES OF TREND: 1979-2018SEASONAL-RANGE

 

FIGURE 2 LINEAR REGRESSION: ARCTIC OCEAN AIR TEMPERATUREREG

 

FIGURE 3: REGRESSION RESIDUALS AS MULTIPLES OF TRENDRESID-MULTIPLES

 

FIGURE 4: TEMPERATURE FORECASTS 2018-20482018FORECAST

 

FIGURE 5: SOURCES OF GEOTHERMAL HEAT IN THE ARCTICbandicam 2019-07-01 16-29-44-526

 

 

 

 

 

 

 

 

 

THIS POST IS A SUMMARY OF SOME METHODOLOGICAL AND STATISTICAL ISSUES IN ANTHROPOGENIC GLOBAL WARMING AND CLIMATE CHANGE (AGW) PRESENTED IN A NUMBER OF RELATED POSTS ON THIS SITE. 

 

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  1. ISSUE #1 > THE RESPONSIVENESS OF ATMOSPHERIC COMPOSITION TO FOSSIL FUEL EMISSIONS: The human cause of warming begins with the argument that our use of fossil fuels has caused atmospheric CO2 concentration to rise and conversely, that causal relationship implies that climate action in the form of reducing or eliminating fossil fuel emissions will reduce or halt the rise in atmospheric CO2 and thus attenuate the rate of warming attributed to atmospheric composition. Thus, a fundamental and necessary condition for AGW is that a causal relationship must exist between atmospheric composition and fossil fuel emissions such that the observed changes in atmospheric composition since pre-industrial times can be explained in terms of fossil fuel emissions of the industrial economy. An annual time scale is assumed in climate science. This relationship is tested in four different posts on this site and the results are summarized below.
  2. TEST#1[LINK] > Is atmospheric CO2 concentration responsive to emissions at an annual time scale? Detrended correlation analysis is used to test this relationship. The detrending procedure removes the spurious effect of shared trends on correlation so that only the responsiveness at the specified time scale is measured in the correlation. Although climate science assumes an annual time scale, time scales from one to five years are tested. The results are tabulated in Paragraph#3 below. There are two columns of results for each time scale, the correlation and the detrended correlation. Although strong correlations from ρ=0.742 for a 1-year time scale to ρ=0.931 for a 5-year time scale are seen in the source data time series, these correlations do not survive into the detrended series where no statistically significant correlation is found. We conclude that the data do not provide sufficient evidence that atmospheric CO2 concentration is responsive to fossil fuel emissions.
  3. COMPO-CHART
  4. TEST#2 > [LINK] > Can nature’s carbon cycle flows be measured with sufficient accuracy to detect the presence of fossil fuel emissions? As seen in the IPCC carbon cycle flows presented in the linked document, the estimated mean values of the flows of the carbon cycle, with flow uncertainties not considered, provide an exact mass balance in the presence of fossil fuel emissions with the so called “Airborne Fraction” computed as 50%, meaning that the mass balance shows that 50% of the CO2 in fossil fuel emissions remain in the atmosphere where they change atmospheric CO2 concentration and cause anthropogenic global warming (AGW). Yet, these flow estimates contain very large uncertainties because they cannot be directly measured but must be inferred. In the related post a statistical test is devised to determine whether the much smaller emissions can be detected in the presence of much larger carbon cycle flows when their large uncertainties are considered. In the related post [LINK] , a Monte Carlo simulation is devised to estimate the highest value of the unknown standard deviations in carbon cycle flows at which we can detect the presence of CO2 in fossil fuel emissions. In the test, an uncertain flow account is considered to be in balance as long as the Null Hypothesis that the sum of the flows is zero cannot be rejected. The alpha error rate for the test is set to a high value of alpha=0.10 to ensure that any reasonable ability to discriminate between the flow account WITH Anthropogenic Emissions from a the flow account WITHOUT Anthropogenic Emissions is taken as evidence that the relatively small fossil fuel emissions can be detected in the presence of much larger and uncertain natural flows.
  5. In the simulation we assign different levels of uncertainty to the flows for which no uncertainty data are available and test the null hypothesis that the flows balance with anthropogenic emissions (AE) included and again with AE excluded. If the flows balance when AE are included and they don’t balance when AE are excluded then we conclude that the presence of the AE can be detected at that level of uncertainty. However, if the flows balance with and without AE then we conclude that the stochastic flow account is not sensitive to AE at that level of uncertainty. If the presence of AE cannot be detected no role for their effect on climate can be deduced from the data at that level of uncertainty in natural flows. The p-values for hypothesis tests for uncertainties in the natural flows from 1% of mean to 6.5% of mean are tabulated in Paragraph#6. The results show that when nature’s carbon cycle flows contain an uncertainty of 2% of the mean or less, the carbon cycle flow account can detect the presence of fossil fuel emissions. The presence of fossil fuel emissions cannot be detected at higher carbon cycle flow uncertainties. The lowest uncertainty found in the carbon cycle flows is 6.5% for photosynthesis. The other uncertainties are much larger and their flows are estimated to be higher than fossil fuel emissions by at least an order of magnitude. Therefore, given the uncertainty in our estimate of natural carbon cycle flows, it is not possible to determine the impact of fossil fuel emissions. 
  6. ISSUE #2 > THE RESPONSIVENESS OF SURFACE TEMPERATURE TO FOSSIL FUEL EMISSIONS: Anthropogenic global warming (AGW) theory says that fossil fuel emissions cause warming and that their reduction and eventual elimination can be used to attenuate the rate of warming and this option is offered and demanded as the “climate action” plan needed to save the world from the destructive effects forecast for uncontrolled AGW. These relationships imply that a correlation must exist between the rate of emissions and the rate of warming and in fact, climate science has presented just such a correlation. It is called the Transient Climate Response to Cumulative Emissions (TCRE) described more fully in a related post [LINK] . And in fact, the TCRE provides the structure and mathematics of the proposed climate action in terms of the so called carbon budgets proposed to constrain warming to a given target level. The TCRE derives from the observation by Damon Matthews and others in 2009 that a near perfect proportionality exists between cumulative emissions and cumulative warming.
  7. TEST#1 > Does the TCRE imply that the rate of warming is related to the rate of emissions such that climate action plans of reducing emissions can be used to attenuate the rate of warming? A test for this correlation is presented in a related post [LINK] where it is shown that a time series of the cumulative values of another time series has neither time scale nor degrees of freedom. The details of the proof of this condition are provided in the post on carbon budgets where it is also shown that the observed correlation derives not from responsiveness of warming to emissions but from a fortuitous sign pattern in which emissions are always positive and in a time of rising temperatures, annual warming is mostly positive [LINK] where it is shown for example, that the TCRE correlation exists in random numbers if the same sign pattern is inserted into the random numbers and disappears when the sign pattern is also random. The relevant GIF charts are reproduced here in {Paragraph#9 and Paragraph#10 below random numbers in the left frame and their cumulative values in the right frame}. The difference between the two charts is that in #9 the random numbers are truly random with no sign pattern imposed meaning that positive and negative values are equally likely; whereas in #10 the random number generator for both x and y favors positive values 55% to 45%. The analysis of the TCRE in these related posts implies that the observed correlation is illusory and spurious and has no implication for the real world phenomena the data apparently represent. Therefore, the TCRE has no interpretation in terms of a causal relationship between emissions and warming.
  8. UNCON-SOURCE-GIFUNCON-CUM-GIF
  9. CON-SOURCE-GIFCON-CUM-GIF
  10. The only information content of the TCRE is the sign pattern. If the the two time series have a common sign bias, either both positive or both negative, the correlation will be positive. If the the two time series have different sign biases, one positive and the other negative, the correlation will be negative. If the the two time series have no sign bias, no correlation will be found. Therefore, the only information content of the TCRE is the sign pattern and no rational interpretation of such a proportionality exists in terms of a causal relationship that can be used in the construction of carbon budgets. The TCRE carbon budgets of climate science is a a meaningless exercise with an illusory statistic. 
  11. TEST#2 > The problem with the TCRE correlation is that it has no time scale and no degrees of freedom. Both issues can be resolved by inserting a fixed time scale X into the TCRE computation such that the correlation is rendered statistically valid as TCREX. The second research question is therefore, {Does the TCREX show that the rate of warming is responsive to the rate of emissions} such that climate action plans of reducing emissions can be used to attenuate the rate of warming? This test is carried out in a related post [LINK] with time scales of ten to thirty years. The test is carried out with both climate model estimations of global mean temperature (RCP) and reconstructions of global mean temperature from the instrumental record  (HADCRUT4). The results of detrended correlation analysis are summarized in Paragraph#13 below. They show strong statistically significant detrended correlations in the theoretical temperatures from climate models but no statistically significant result is found in the observational data. The agreement with the theoretical temperature series validates the procedure and therefore the absence of evidence to relate observational data to emissions provides convincing evidence that when the TCRE measure is corrected to insert time scale and degrees of freedom, the “near perfect proportionality” of the TCRE disappears. We conclude from these results that no evidence is found in the observational data that the rate of warming is responsive to the rate of emissions. [DETAILS]
  12. SUMMARY-TABLE
  13. ISSUE#3 > CARBON BUDGETS: The claimed catastrophic impacts of AGW Climate Change serve as the needed motivation for Climate Action. Climate action involves the reduction and eventual elimination of the use of fossil fuels – and thereby of fossil fuel emissions. The theoretical linkage between climate change and climate action is the Carbon Budget. A climate action plan specifies the maximum warming target over a specified time span. The corresponding carbon budget is the maximum amount of carbon in fossil fuel emissions that can be emitted over that time period to comply with the climate action plan. The statistical issue in this case arises because the carbon budget is based on the flawed TCRE – Transient Climate Response to Cumulative Emissions discussed  above in Issue#2.
  14. TEST#1 > The use of the illusory TCRE correlation in the construction of carbon budgets renders the carbon budget equally spurious and illusory as described in this related post [LINK] . It shows that the carbon budget computed from the TCRE has no interpretation in the real world because it is based on an illusory correlation that is the creation of sign patterns and not based on the responsiveness of temperature to emissions. The further consideration is that the absence of time scale and degrees of freedom in the carbon budget renders it a spurious statistic that has no interpretation in terms of the emissions and warming dynamics it apparently represents.
  15. TEST#2 > A further test of the validity of the carbon budget is seen in the Remaining Carbon Budget Puzzle (RCBPthat has created a state of confusion in climate science as described in a related post [LINK] . In brief, the RCBP issue is that the carbon budget for the full span of the budget period does not equal the sum of the carbon budgets computed for its sub-spans. There is a simple statistics explanation of this apparent oddity in terms of the spuriousness of the correlation and the TCRE regression coefficient. The positive TCRE correlation is a creation of a fortuitous sign pattern such that emissions are always positive and during a time of warming, annual warming values are mostly positive, as shown in a related post [LINK] . Thus, the TCRE regression coefficient is determined by the fraction of annual warming values that are positive; and this fraction is not likely to be the same in different sub-spans and not the same in any given sub-span as in the full span. It is this statistical oddity and not the absence of Earth System climate model variables that explains the RCBP. And yet, as seen in the literature, climate science reaches out to Earth System Models to explain and then to apparently solve the RCBP, as shown in a related post [LINK] . In summary, the Remaining Carbon Budget issue is a simple statistical issue that has been interpreted in climate science in terms of AGW climate forcing portfolio needed to implement carbon budgets.
  16. ISSUE#4: > WILL CLIMATE ACTION MODERATE THE RATE OF SEA LEVEL RISE? A principal argument for climate action has been the fear of sea level rise that threatens hundreds of millions of people in vulnerable small island states, low lying deltas such as Bangladesh, and coastal communities such as Florida [LINK] [LINK] [LINK] [LINK] and it is therefore proposed that climate action in the form of reducing or eliminating fossil fuel emissions must be taken to attenuate the rate of sea level rise [LINK] . The only empirical evidence presented to relate sea level rise to emissions is the paper by Professor Peter Clark of Oregon State University [LINK] [Reducing carbon emissions will limit sea level rise] . The Clark paper shows a strong and statistically significant correlation between cumulative emissions and cumulative sea level rise in the TCRE format and thus suffers from the same limitations as the TCRE in that there is no time scale and no degrees of freedom, and that the correlation derives from a sign pattern in that emissions are always positive and annual sea level rise values are mostly positive.
  17. TEST#1 > The correlation presented by the Peter Clark paper is evaluated in a related post and found to be spurious and illusory because it has neither time scale nor degrees of freedom [LINK] . This spurious correlation contains no information in terms of a causal relationship between emissions and sea level rise. It is necessary to test the correlation with time scale and degrees of freedom restored.
  18. TEST#2 > The Peter Clark correlation is tested in a related post [LINK] with finite time scales inserted. Time scales of 30, 35, 40, 45, and 50 years are used in the test. The correlation and detrended correlation between emissions and sea level rise are shown in the summary of results table in Paragraph#20 . A statistically significant positive correlation is required to support the causation hypothesis being tested. Although such correlations are seen in the source data, none of them survives into the detrended series where the correlations are negative. Note that source data correlations between time series data is influenced by shared trends and therefore have no interpretation in terms of responsiveness at a finite time scale. We conclude from these results that, although a significant correlation is seen between the cumulative values, no evidence of correlation between emissions and sea level rise is found in the data at finite time scales and with degrees of freedom restored. Thus there is no evidence that climate action in the form of reducing fossil fuel emissions will attenuate sea level rise.
  19. SUMMARY
  20. ISSUE#5 > THE IMPACT OF AGW ON TROPICAL CYCLONES:   This issue is presented in a related post [LINK]
  21. ISSUE#6 > THE IMPACT OF AGW ON SEA ICE: This issue is presented in three related posts [LINK] [LINK] [LINK] 

 

 

 

 

 

 

 

THIS POST EXAMINES THE CLIMATE SCIENCE POSITION THAT THE USE OF FOSSIL FUELS HAS INCREASED THE DESTRUCTION CAUSED BY TROPICAL CYCLONES. 

 

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  1. The claimed causal connection between AGW climate change and the destructiveness of tropical cyclones did not emerge from the science nor from an extensive study of historical data but from an unlikely event in 2005 when Hurricane Katrina damaged a levee system that had not been properly maintained. The damage to the levee caused a catastrophic flooding of New Orleans that became the signature issue in the destructiveness of Hurricane Katrina as seen in the 2005-2009 reports in paragraph#2 below. The role of levee management in the destruction was downplayed and forgotten and the entire destruction was thus attributed to fossil fueled climate change with the subsumed climate action lesson of Katrina being that such destruction can and must be attenuated by reducing and eventually eliminating the use of fossil fuels.
  2. Hurricane Katrina Historical Notes: (i) HURRICANE KATRINA IS THE HARBINGER OF WORSE YET TO COME: The IPCC claimed that it had the scientific evidence to prove that our use of fossil fuels caused Hurricane Katrina to forecast with a great certainty that there was more to come in the 2006 hurricane season but the 2006 hurricane season turned out to be milder than normal. The IPCC blamed the dissipation of El Nino for the mild hurricane season in 2006 and issued a new warning that 2007 will be the hottest year on record and will bring a killer hurricane season worse than 2005 but the 2007 forecast also failed. The IPCC’s dream hurricane season has finally arrived in 2008 unannounced and unexpected with strong hurricanes Gustav and Hanna expected to be followed by Ike and a dozen others before the season is through. More info: [LINK] . (ii) The IPCC’s claim that Hurricane Katrina was caused by man-made global warming has been thoroughly discredited and their forecasts for more severe hurricane seasons in 2006 and 2007 have been proven wrong. They are merchants of fear and their method is the dissemination of convenient lies. More info: [LINK] . (iii) Climate science shows that AGW climate change is increasing the frequency and severity of extreme weather as for example Hurricane Katrina. Further research shows a causal link between AGW and increasing wave intensity that provides direct evidence of the extreme weather impacts of AGW. More info: [LINK] . (iv) 2009: In 2005 climate science declared that Hurricane Katrina was the harbinger of killer super storms yet to come created by fossil fueled global warming but after no further cyclone activity in the North Atlantic Basin in the next three years, new evidence for the destructiveness of AGW extreme weather was found in Cyclone Nargis in the North Indian Basin. Though not unusually strong, Nargis did create a freak storm surge in rising tides that swept up the Irrawaddy River in Burma and claimed a horrific death toll. Nargis thus became an AGW issue and climate scientists changed their extreme weather focus from the North Atlantic Basin to the North Indian Basin saying that Cyclone Nargis was a creation of climate change caused by fossil fuel emissions and as the harbinger of “destruction on a global scale” by human caused global warming. More [LINK] .
  3. The Climate Science of Hurricane Katrina:  It was thus that the climate science of the destructiveness of hurricanes did not predict Katrina but was in fact constructed from Katrina based only on the destructiveness of the flood caused by the break in the levee system and by discounting the greater climatology data that it was Wilma, not Katrina, that was by far the stronger hurricane of the 2005 season but Katrina, not Wilma, was clearly the better tool to sell AGW’s fear based climate action agenda. This relationship between climate science and real science is seen more clearly in the foundational and keynote paper by noted MIT climate scientist Professor Kerry Emanuel reviewed in detail in a related post [LINK] . There it is shown that the need by climate science to establish the fear of climate change in terms of hurricanes made it possible for Professor Emanuel to abandon all pretension to scientific principles and statistical rigor to publish in a peer reviewed journal a circular reasoning paper that begins with the assumption that AGW increases the destructiveness of hurricanes and then proves that AGW increases the destructiveness of hurricanes [LINK] .
  4. Yet another issue is that the single minded focus on the North Atlantic Basin (NA) for the detection of the impact of climate change on tropical cyclone destructiveness during periods when NA is unusually active is a form of circular reasoning; particularly so because NA by itself is not a globally important source of cyclone energy. An additional consideration is the finding by Knutson (2010) and others that total cyclone energy variance for a single basin is too large to come to meaningful conclusions about trends and recommended that only the aggregate of all six basins could contain useful trend information.
  5. There are six tropical cyclone basins in the world where tropical cyclones form.  These are the West Pacific (WP), South Indian Ocean (SI), East Pacific (EP), North Atlantic (NA), North Indian Ocean (NI), and the South Pacific (SP). The most intensive and active  basin is the West Pacific Basin where tropical cyclones are called Typhoons. The North Atlantic Basin, where tropical cyclones are called Hurricanes, is a lesser basin and not a significant source of total global cyclone energy. Of the other four basins, the South Indian Ocean basin is the most active. Together, WP and SI generate more than 60% of the total global cyclone energy with the East Pacific and the North Atlantic together coming in second with about 25% of the world’s cyclone energy. The North Atlantic generates about 14% of the world’s cyclone energy. The details of this comparison are tabulated in Paragraph#6.
  6. BASIN-SUMMARY
  7. Since AGW climate change is proposed as a global phenomenon, its effect on tropical cyclones must be studied and understood only in terms of global measures of tropical cyclone activity and not in terms of convenient localized phenomena that fit the narrative or that might derive from a USA bias of American researchers and the American news media. Here we provide an integration and summary of three related posts where the global impact of AGW on tropical cyclone activity is measured as a global aggregate of all six cyclone basins.
  8. Study#1 > Trends[LINK] . The trend study presents data for total cyclone energy for all six basins for the 70-year study period 1945 to 2014. The object variable is the Accumulated Cyclone Energy (ACE) used as a measure of total cyclone energy. Knutson (2010) and others have suggested that year to year variance in cyclone energy is too large and random to draw meaningful interpretation of and recommended a decadal time scale for the study of tropical cyclone trends. Accordingly, the total global ACE for all six cyclone basins is computed for each of the seven decades in the 70-year study period. Trend analysis is carried out by comparing each decade against the other six. The results are summarized in the Table presented in Paragraph#9 below. They show that only two statistically significant differences are found. Specifically, we find that Decade#5 (1985-1994) and Decade#6 (1995-2004) show higher total global cyclone energy than Decade#1 (1945-1954). No other statistically significant difference is found among the seven decades studied.
  9. It is tempting here to conclude that the higher global cyclone energy in the two recent decades from 1985 to 2004 than in the decade 1945-1954 can and should be attributed to AGW climate change but there are other well understood considerations that explain this difference. It is well established and generally accepted in the tropical cyclone research community that the early decade in this study, 1945-1954, suffered from a measurement bias such that not all tropical cyclones were detected and of those that were not all were adequately measured. In other words the early data are incomplete and the incompleteness of the data provides a stronger and more rational explanation of the observed statistically significant trend in total cyclone energy. We conclude from these results that he data do not show an impact of AGW climate change in the form of increasing the destructiveness of tropical cyclones. 
  10. Study #2: > SST: [LINK] . Sea surface temperature (SST) is the link that connects climate change with tropical cyclone activity with the proposition that higher SST provides more energy for tropical cyclones that form on the basis of high SST. Cyclone theory tells us that cyclone formation, and intensification are related to SST (Vecchi, 2007) (Knutson, 2010). Testable implications of the theory for empirical research are derived from climate model simulations (Knutson, 2010). Knutson’s work also suggests that the high variance in tropical cyclone activity at an annual time scale or for any single cyclone basin means that data analysis must be carried out on a global basis for all six tropical cyclone basins and time scales longer than annual should be used. Detrended correlation analysis for total cyclone energy and SST are carried out at a decadal time scale 1945-2014. The results are tabulated in Paragraph#12. They show that the high correlation seen between total global cyclone energy (ACE) and global sea surface temperature (SST) derives from a rising trend in both time series and not from a responsiveness of ACE to SST at a decadal time scale.
  11. We conclude from the results presented in Paragraph#8 to Paragraph#12 that no evidence is found for the usual assumption in climate science that AGW climate change is intensifying tropical cyclone activity by way of SST.
  12. Study#3: > Pre-Industrial: [LINK] . The fundamental theoretical  basis for the theory of AGW climate change is a stark difference between “pre-industrial times” and the “era of the industrial economy” in terms of climate as assumed in climate science. A testable implication of the claimed impact of AGW climate change on tropical cyclones in terms of this dichotomy is that a comparison of the two eras should show a stark difference in tropical cyclone activity in terms of an absence of intense and destructive tropical cyclones in the pre-industrial era.
  13. The Treasure Coast Hurricanes of 1715 & 1733The Dreadful Hurricane of 1667, The Calcutta Cyclone of 1737, The Great Hurricane of 1780, The Great September Gale of 1815, The Coringa Cyclone of 1839, and The Last Island Hurricane of 1856, The San Diego Hurricane of 1858 are described and presented as tropical cyclones with intensity and destructiveness comparable to the high profile hurricanes cited by climate science as evidence of the impact of AGW climate change. We conclude from the comparison that it does not provide convincing evidence that tropical cyclones such as the destructive hurricanes cited by climate science as a creation of AGW are unique to the industrial economy that could not have occurred in pre-industrial times. It is also noted that the strongest and most destructive tropical cyclone of the post industrial era was the monster Bhola Cyclone [LINK][LINK]that killed half a million people in Bangladesh. It occurred way back in 1970 right in the middle of the 1970s cooling period[LINK]that had sparked fears of a return to Little Ice Age conditions[LINK] .
  14. CONCLUSION: The data and their interpretation presented in these posts reveal serious weaknesses in the claim by climate science that the industrial economy has caused greater intensity and destructiveness of tropical cyclones by way of global warming and rising sea surface temperature.

 

1715cyclone

 

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THE RELEVANT LITERATURE

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  5. Chan, J. (2006). Comments on “changes in tropical cyclone number, duration, and intensityi a warming environment”. Science, 311: 1731b.
  6. Dodla, V. (2007). GIS based analysis of climate change impacts on tropical cyclones over Bay of Bengal. Jackson, MS, 39217, USA: Trent Lott Geospatial and Visualization Research Center, Jackson State University.
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  14. Girishkumar, M. (2012). The influences of ENSO on tropical cyclone activity in the Bay of Bengal during October-December. Journal of Geophysical Research, V.117, C02033, doi:10.1029/2011JC007417.
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THIS POST IS A CRITICAL REVIEW OF PELLIGRINI ETAL 2018 WHERE THE AUTHORS REPORT AN IMPACT OF FOREST FIRES THAT HAS CLIMATE CHANGE IMPLICATIONS IN TERMS OF THE ABILITY OF SOILS TO SEQUESTER CARBON.

  1. The lead author of the paper (photo above) is Adam Pellegrini PhD, Earth System Science Department, Stanford University where he is a NOAA Climate and Global Change Postdoc Fellow. The paper (item#14 in the “Forest Fire Effects on Topsoil Chemistry” Bibliography below) reports findings on the effect of forest fires on soil chemistry. It is an extensive study across 48 sites globally distributed and three different kinds of forest, grasslands, broad leaf, and needle leaf. The authors studied the effects of forest fires on the chemistry of topsoil, the uppermost loose layer of the soil about six inches in depth normally rich in life and organic matter. Unlike the other studies of forest fires listed below where effects of prescribed fires and wildfires are reported, the Pelligrini 2018 study is experimental where forest fires in selected regions and forest types are intentionally started by the researchers with different frequency of fires in order to study the long term effects over a period of 65 years.
  2. They found that frequent fires in grasslands and broad leaf forests  caused significant declines in carbon and nitrogen in topsoil. No significant effect of frequent fires was found in needleleaf forests or for infrequent fires in any of the three forest types. The findings are consistent with field data and with a dynamic computer model of global vegetation. The findings are thus taken as a validation of the dynamic global vegetation model (DGVM).
  3. Further study with the DGVM predicts that the long-term losses of soil nitrogen  from more frequent burning may lower the ability of the topsoil to perform its assumed carbon sequestration function that is relevant to the carbon cycle and climate change because the carbon sequestration function of healthy topsoil sequesters 20% of the carbon released by wildfire activity in forests and grasslands.
  4. The relevance of this finding to the climate change issue is that if wildfire frequency is increased by climate change, the expected impact on the topsoil’s ability to sequester carbon may act as a feedback by increasing atmospheric CO2 concentration and thereby accelerating climate change severity and thereby the rise in wildfire frequency.
  5. The assumed causal connection, that AGW climate change increases wildfire frequency, is derived from the various works of Leroy Westerling, Professor of Climatology, the University of California at Merced from 2006 to 2011 and some later works by other authors. The references are listed in the “climate change wildfire” bibliography below. These references show that ….
  6. In certain specific regions (eg California), but not in others, wildfires have increased since the mid-1980s while at the same time AGW climate change was causing increased warmth, desiccation, and wind speed that could enhance wildfire conditions. These relationships are taken as evidence that AGW climate change did in fact cause an increase in wildfires. The weaknesses in this argument are many as listed below.
  7. (i) Evidence of the effect of global warming on wildfire frequency or severity is not established globally; but rather for specific regions where rising devastation by wildfires is known to have occurred are selected for the evaluation; (ii) That variable y is rising while at the same time variable x was also rising establishes neither correlation nor causation even when x and y could have a causation relationship; yet this is the sole argument presented for the attribution of wildfire severity and/or frequency to AGW other than the rationalization that AGW is expected to cause increased warmth, desiccation, an wind speed (iii) Other factors that are also concomitant are not considered such as changes in California logging regulations that were made around the time when the Spotted Owl was declared to be an endangered species threatened by logging. Logging in California’s wilderness was banned. At the same time, prescribed forest management fires were banned or severely curtailed. These management changes also occurred in the late 1980s and early 1990s but they have been removed from consideration to make way for a single minded focus on a pre-determined causation relationship between AGW climate change and wildfires. Even more egregious, if indeed the wildfire devastation in California is related to the failure of forest management by way of inadequate prescribed fires, the Pellegrini 2018 implication that prescribed fires are bad because of lost carbon sequestration is the exact opposite of the forest management change needed in California. (iv) Computer modeling of the impact of AGW climate change on wildfires will of course show that relationship because it has been programmed into it. These results serve only to show that the model works the way it is supposed to work and can’t be presented as evidence that the observed increase in California wildfire devastation since the 1990s must have been caused by AGW. Computer models of expected theoretical relationships are an expression of the theory itself and it cannot also serve as the data to test theory.
  8. The works listed in the AGW Wildfire bibliography below, particularly those by Professor Westerling are biased in this way. Results of modeling studies and climate theories of the impact of AGW climate change on wildfires have created a sense that the truth of the causation relationship is a given and that the observational evidence plays the minor role of providing the kind of data that are expected in going through the required formality for a causation that has been fully accepted by the researchers apriori. In other words, that AGW climate change increases wildfire devastation is the null hypothesis. However, it is necessary for empirical test of theory to be carried out in exactly the opposite way where the null hypothesis is the absence of the causation relationship and sufficient and convincing unbiased evidence must be presented before the null hypothesis can be rejected.
  9. The finding in {Pellegrini, Adam FA, et al. “Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity.” Nature 553.7687 (2018)} that climate change causes loss of soil carbon sequestration which in turn exacerbates climate change contains two significant flaws. The first is, as stated above, insufficient evidence is provided for the relationship that AGW climate change increases wildfire devastation. The second flaw in the Pellegrini 2018 paper is the interpretation of carbon sequestration loss in soils in terms of AGW climate change. AGW is a theory that the carbon in fossil fuels are extraneous and unknown to the current carbon cycle and climate system such that this system of nature suffered an unnatural perturbation when humans dug up ancient carbon in fossil fuels and injected that extraneous carbon, (carbon that does not belong in the current account of the carbon cycle), into the carbon cycle and climate system.
  10. A related issue is the importance of the Industrial Revolution that divides climate history into pre-industrial (the reference climate relative to which AGW is measured as the impact of the industrial economy), and the post industrial era where fossil fuel emissions of the industrial economy is said to have created a new, unprecedented, and artificial climate regime. AGW climate change must be understood only in this context. Thus, the impact of wildfires in general is not an issue because there were wildfires in pre-industrial times. Therefore only the effect of those wildfires that would not have been without the industrial economy can serve as a creation of fossil fuels and thus be related to AGW and used as climate change arguments.
  11. The argument made or implied by the authors is that the loss of carbon sequestration capacity of topsoil due to forest fires, whether prescribed control burns or wildfires, will serve to increase atmospheric CO2 concentration and thereby act as an AGW feedback loop so that the more warming there is the more forest fires there will be and the more soil sequestration that will be lost and so even more warming there will be and so on. The statistical significance of this relationship must first be established in the context of the very high uncertainties in carbon cycle flows described in a related post [LINK] . The interpretation of this change must be made in the context of the AGW theoretical framework that AGW warming is the result of the perturbation of the carbon cycle with external carbon dug up from under the ground where it had been sequestered for millions of years.
  12. The related post linked above [LINK] shows extremely high uncertainties as expected since carbon cycle flows are not directly measurable but must be inferred. For example, carbon cycle flows related to “land use change” are listed as Land use change: surface to atmosphere:Mean=1.1,SD=0.8 implying a 90% confidence interval of -0.216 to 2.416 GT (IPCC AR5 2018). The relevance of the proposed forest fire effect must be shown in the context of these large uncertainties in unmeasurable carbon cycle flows.
  13. An analysis is presented in related posts on this site that shows that given the large uncertainties in carbon cycle flows, fossil fuel emissions are statistically not detectable [LINK] [LINK] . Carbon cycle flows are not directly measurable but must be inferred. Given these uncertainties in carbon cycle flows, a global estimate of carbon sequestration lost due to forest fires and its uncertainty must be estimated and shown to be detectable and relevant in the context of the carbon cycle and its extreme uncertainties. Until these additional information can be made available, the findings of {Pellegrini, Adam FA, et al. “Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity.” Nature 553.7687 (2018)}, though interesting, cannot be assumed to have practical implications for AGW climate change and the corresponding propositions for climate action.
  14. In summary, what we see in the Spotted Owl case is that an excess of environmentalism zeal can harm the environment. That pattern now emerges in climate change environmentalism.

 

 

This post was motivated by a related post on the WUWT site [LINK] 

 

 

AGW AND WILDFIRE FREQUENCY:  BIBLIOGRAPHY

Featured Author: Anthony Leroy Westerling, Professor of Climatology, UC Merced

westerling_leroy

  1. Fried, Jeremy S., Margaret S. Torn, and Evan Mills. “The impact of climate change on wildfire severity: a regional forecast for northern California.” Climatic change 64.1-2 (2004): 169-191.  We estimated the impact of climatic change on wildland fire and suppression effectiveness in northern California by linking general circulation model (GCM) output to local weather and fire records and projecting fire outcomes with an initial-attack suppression model. The warmer and windier conditions corresponding to a 2 × CO2 climate scenario produced fires that burned more intensely and spread faster in most locations. Despite enhancement of fire suppression efforts, the number of escaped fires (those exceeding initial containment limits) increased 51% in the south San Francisco Bay area, 125% in the Sierra Nevada, and did not change on the north coast. Changes in area burned by contained fires were 41%, 41% and –8%, respectively. When interpolated to most of northern California’s wildlands, these results translate to an average annual increase of 114 escapes (a doubling of the current frequency) and an additional 5,000 hectares (a 50% increase) burned by contained fires. On average, the fire return intervals in grass and brush vegetation types were cut in half. The estimates reported represent a minimum expected change, or best-case forecast. In addition to the increased suppression costs and economic damages, changes in fire severity of this magnitude would have widespread impacts on vegetation distribution, forest condition, and carbon storage, and greatly increase the risk to property, natural resources and human life. [FULL TEXT PDF]
  2. Westerling, Anthony L., et al. “Warming and earlier spring increase western US forest wildfire activity.” science 313.5789 (2006): 940-943Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire duration, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt. In the Conclusions section of the paper the authors write “Robust statistical associations between wildfire and hydroclimate in western forests indicate that increased wildfire activity over recent decades reflects sub-regional responses to changes in climate. Historical wildfire observations exhibit an abrupt transition in the mid-1980s from a regime of infrequent large wildfires of short (average of 1 week) duration to one with much more frequent and longer burning (5 weeks) fires. This transition was marked by a shift toward unusually warm springs, longer summer dry seasons, drier vegetation (which provoked more and longer burning large wildfires), and longer fire seasons. Reduced winter precipitation and an early spring snowmelt played a role in this shift. Increases in wildfire were particularly strong in mid-elevation forests. [LINK TO FULL TEXT DOWNLOAD]
  3. Scholze, Marko, et al. “A climate-change risk analysis for world ecosystems.” Proceedings of the National Academy of Sciences 103.35 (2006): 13116-13120.  We quantify the risks of climate-induced changes in key ecosystem processes during the 21st century by forcing a dynamic global vegetation model (DGVM) with multiple scenarios from 16 climate models and mapping the proportions of model runs showing forest/nonforest shifts or exceedance of natural variability in wildfire frequency and freshwater supply. Our analysis does not assign probabilities to scenarios or weights to models. Instead, we consider distribution of outcomes within three sets of model runs grouped by the amount of global warming they simulate: <2°C (including simulations in which atmospheric composition is held constant, i.e., in which the only climate change is due to greenhouse gases already emitted), 2–3°C, and >3°C. High risk of forest loss is shown for Eurasia, eastern China, Canada, Central America, and Amazonia, with forest extensions into the Arctic and semiarid savannas; more frequent wildfire in Amazonia, the far north, and many semiarid regions; more runoff north of 50°N and in tropical Africa and northwestern South America; and less runoff in West Africa, Central America, southern Europe, and the eastern U.S. Substantially larger areas are affected for global warming >3°C than for <2°C; some features appear only at higher warming levels. A land carbon sink of ≈1 Pg of C per yr is simulated for the late 20th century, but for >3°C this sink converts to a carbon source during the 21st century (implying a positive climate feedback) in 44% of cases. The risks continue increasing over the following 200 years, even with atmospheric composition held constant. [FULL TEXT PDF DOWNLOAD] .
  4. Westerling, A. L., and B. P. Bryant. “Climate change and wildfire in California.” Climatic Change 87.1 (2008): 231-249Wildfire risks for California under four climatic change scenarios were statistically modeled as functions of climate, hydrology, and topography. Wildfire risks for the GFDL and PCM global climate models (note: GFDL and PCM are different resolutions of GCM climate models) and the A2 and B1 emissions scenarios were compared for 2005–2034, 2035–2064, and 2070–2099 against a modeled 1961–1990 reference period in California and neighboring states. Outcomes for the GFDL model runs, which exhibit higher temperatures than the PCM model runs, diverged sharply for different kinds of fire regimes, with increased temperatures promoting greater large fire frequency in wetter, forested areas, via the effects of warmer temperatures on fuel flammability. At the same time, reduced moisture availability due to lower precipitation and higher temperatures led to reduced fire risks in some locations where fuel flammability may be less important than the availability of fine fuels. Property damages due to wildfires were also modeled using the 2000 U.S. Census to describe the location and density of residential structures. In this analysis the largest changes in property damages under the climate change scenarios occurred in wildland/urban interfaces proximate to major metropolitan areas in coastal southern California, the Bay Area, and in the Sierra foothills northeast of Sacramento. [FULL TEXT PDF]
  5. Cannon, Susan H., and Jerry DeGraff. “The increasing wildfire and post-fire debris-flow threat in western USA, and implications for consequences of climate change.” Landslides–disaster risk reduction. Springer, Berlin, Heidelberg, 2009. 177-190.  In southern California and the intermountain west of the USA, debris flows generated from recently-burned basins pose significant hazards. Increases in the frequency and size of wildfires throughout the western USA can be attributed to increases in the number of fire ignitions, fire suppression practices, and climatic influences. Increased urbanization throughout the western USA, combined with the increased wildfire magnitude and frequency, carries with it the increased threat of subsequent debris-flow occurrence. Differences between rainfall thresholds and empirical debris-flow susceptibility models for southern California and the intermountain west indicate a strong influence of climatic and geologic settings on post-fire debris-flow potential. The linkages between wildfires, debris-flow occurrence, and global warming suggests that the experiences in the western United States are highly likely to be duplicated in many other parts of the world, and necessitate hazard assessment tools that are specific to local climates and physiographies. [FULL TEXT PDF]
  6. Abatzoglou, John T., and Crystal A. Kolden. “Climate change in western US deserts: potential for increased wildfire and invasive annual grasses.” Rangeland Ecology & Management 64.5 (2011): 471-478.  The influence of climate change on future invasions depends on both climate suitability that defines a potential species range and the mechanisms that facilitate invasions and contractions. A suite of downscaled climate projections for the mid–21st century was used to examine changes in physically based mechanisms, including critical physiological temperature thresholds, the timing and availability of moisture, and the potential for large wildfires. Results suggest widespread changes in 1) the length of the freeze-free season that may favor cold-intolerant annual grasses, 2) changes in the frequency of wet winters that may alter the potential for establishment of invasive annual grasses, and 3) an earlier onset of fire season and a lengthening of the window during which conditions are conducive to fire ignition and growth furthering the fire-invasive feedback loop. We propose that a coupled approach combining bioclimatic envelope modeling with mechanistic modeling targeted to a given species can help land managers identify locations and species that pose the highest level of overall risk of conversion associated with the multiple stressors of climate change. [FULL TEXT PDF]
  7. Girardin, Martin P., et al. “Vegetation limits the impact of a warm climate on boreal wildfires.” New Phytologist 199.4 (2013): 1001-1011.  Strategic introduction of less flammable broadleaf vegetation into landscapes was suggested as a management strategy for decreasing the risk of boreal wildfires projected under climatic change. However, the realization and strength of this offsetting effect in an actual environment remain to be demonstrated. Here we combined paleoecological data, global climate models and wildfire modelling to assess regional fire frequency (RegFF, i.e. the number of fires through time) in boreal forests as it relates to tree species composition and climate over millennial time‐scales. Lacustrine charcoals from northern landscapes of eastern boreal Canada indicate that RegFF regional fire frequency during the mid‐Holocene (6000–3000 yr ago) was significantly higher than pre‐industrial RegFF (ad c. 1750). In southern landscapes, RegFF was not significantly higher than the pre‐industrial RegFF in spite of the declining drought severity. The modelling experiment indicates that the high fire risk brought about by a warmer and drier climate in the south during the mid‐Holocene was offset by a higher broadleaf component. Our data highlight an important function for broadleaf vegetation in determining boreal RegFF in a warmer climate. We estimate that its feedback may be large enough to offset the projected climate change impacts on drought conditions. [FULL TEXT]  
  8. Westerling, Anthony LeRoy. “Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring.” Philosophical Transactions of the Royal Society B: Biological Sciences 371.1696 (2016): 20150178.  Prior work shows western US forest wildfire activity increased abruptly in the mid-1980s. Large forest wildfires and areas burned in them have continued to increase over recent decades, with most of the increase in lightning-ignited fires. Northern US Rockies forests dominated early increases in wildfire activity, and still contributed 50% of the increase in large fires over the last decade. However, the percentage growth in wildfire activity in Pacific northwestern and southwestern US forests has rapidly increased over the last two decades. Wildfire numbers and burned area are also increasing in non-forest vegetation types. Wildfire activity appears strongly associated with warming and earlier spring snowmelt. Analysis of the drivers of forest wildfire sensitivity to changes in the timing of spring demonstrates that forests at elevations where the historical mean snow-free season ranged between two and four months, with relatively high cumulative warm-season actual evapotranspiration, have been most affected. Increases in large wildfires associated with earlier spring snowmelt scale exponentially with changes in moisture deficit, and moisture deficit changes can explain most of the spatial variability in forest wildfire regime response to the timing of spring. [FULL TEXT]

 

 

 

FOREST FIRE EFFECT ON TOPSOIL CHEMISTRY:  BIBLIOGRAPHY

  1. Shakesby, Richard A., et al. “Impacts of prescribed fire on soil loss and soil quality: an assessment based on an experimentally-burned catchment in central Portugal.” Catena 128 (2015): 278-293Prescribed (controlled) fire has recently been adopted as an important wildfire-fighting strategy in the Mediterranean. Relatively little research, however, has assessed its impacts on soil erosion and soil quality. This paper investigates hillslope-scale losses of soil, organic matter and selected nutrients before and after a ‘worst-case scenario’ prescribed fire in a steep, shrub-vegetated catchment with thin stony soil in central Portugal. Comparison is made with soil erosion measured: (1) on a nearby hillslope burned by wildfire and monitored at the hillslope scale; and (2) on long-unburned terrain at small-plot, hillslope- and catchment-scales. Hillslope-scale pre- and post-fire soil erosion was recorded over periods of 6 weeks to 5 months for (1) 9.5 months pre-fire and 27 months post-fire in the prescribed fire catchment, and (2) c. 3 years post-fire at the wildfire site. Organic matter content, pH, total N, K2O, P2O5, Ca2 + and Mg2 + were measured in the eroded sediment and in pre- and post-prescribed fire surface soil. Results indicate that: (1) both the prescribed fire and the wildfire caused expected marked increases in erosion compared with unburned terrain; and (2) the hillslope-scale post-prescribed fire soil losses (up to 2.41 t ha− 1 yr− 1) exceeded many reported plot-scale post-prescribed fire and post-wildfire erosion rates in the Mediterranean. As a comparison, post-fire erosion for both fire types was less than that caused by some other forms of common soil disturbance (e.g. types of tillage) and even that on undisturbed shrubland in low rainfall areas of the region. Total estimated post-prescribed fire particulate losses of organic matter and nutrients represent only 0.2–2.9% of the content in the upper 2 cm of soil, suggesting only a modest fire effect on soil quality, although this may reflect in part a lack of extreme rainfall events following the fire. The longer-term implications for soil conservation of repeated prescribed fire in the Mediterranean are explored and future research priorities identified.
  2. Pellegrini, Adam FA, et al. “Fire alters ecosystem carbon and nutrients but not plant nutrient stoichiometry or composition in tropical savanna.” Ecology 96.5 (2015): 1275-1285.  Fire and nutrients interact to influence the global distribution and dynamics of the savanna biome, (Biome=large naturally occurring community of flora and fauna such as a forest) but the results of these interactions are both complex and poorly known. A critical but unresolved question is whether short‐term losses of carbon and nutrients caused by fire can trigger long‐term and potentially compensatory responses in the nutrient stoichiometry of plants, or in the abundance of dinitrogen‐fixing trees. There is disagreement in the literature about the potential role of fire on savanna nutrients, and, in turn, on plant stoichiometry and composition. A major limitation has been the lack of fire manipulations over time scales sufficiently long for these interactions to emerge. We use a 58‐year, replicated, large‐scale, fire manipulation experiment in Kruger National Park (South Africa) in savanna to quantify the effect of fire on (1) distributions of carbon, nitrogen, and phosphorus at the ecosystem scale; (2) carbon : nitrogen : phosphorus stoichiometry of above‐ and below-ground tissues of plant species; and (3) abundance of plant functional groups including nitrogen fixers. Our results show dramatic effects of fire on the relative distribution of nutrients in soils, but that individual plant stoichiometry and plant community composition remained unexpectedly resilient. Moreover, measures of nutrients and carbon stable isotopes allowed us to discount the role of tree cover change in favor of the turnover of herbaceous biomass as the primary mechanism that mediates a transition from low to high soil carbon and nutrients in the absence of fire. We conclude that, in contrast to extra‐tropical grasslands or closed‐canopy forests, vegetation in the savanna biome may be uniquely adapted to nutrient losses caused by recurring fire.
  3. Fultz, Lisa M., et al. “Forest wildfire and grassland prescribed fire effects on soil biogeochemical processes and microbial communities: Two case studies in the semi-arid Southwest.” Applied soil ecology 99 (2016): 118-128.  Fire is a natural disturbance that shapes many ecosystems. In semi-arid regions, where high temperatures and low soil moisture limit nutrient cycling and plant growth, fire is critical to supply nutrients and drive vegetation composition. We examined soil chemical and biological properties to assess the short-term impacts of wildfire and prescribed fires on soil functioning in semi-arid regions of Texas. Better understanding of soil organic matter transformation and nutrient cycling processes will aid land managers in predicting ecosystem recovery response post-fire. Soil samples were collected following both prescribed grassland fires in June of 2009 in Lubbock, TX and the April 2012 Livermore Ranch Complex Fire located in the Davis Mountains, TX. Prescribed fire samples (0–2.5 cm) were collected within 6 hours prior to burning and again at 0.5, 24, 48, and 168 hours post-fire to experimentally examine short-term influences of fire and fire frequency (1× vs. 2×) on soil carbon dynamics, inorganic nitrogen, and microbial community composition. Wildfire samples (0–5 cm) were collected two and six months following the wildfire. We evaluated the effects of three burn severity levels and sampled under three tree species (Juniperus deppeanaPinus cembroides, and Quercus grisea). Within 0.5 h of the prescribed fire, CO2 flux, NH4+-N concentration and total microbial biomass (as estimated by total fatty acid methyl esters) increased. A shift in the microbial community from a predominance of fungi to Gram positive bacteria occurred immediately following the fire. Chemical shifts were short lived (decreased within 24 h), but the biotic shift to a dominance of Gram negative bacteria and actinomycetes was measured in samples collected after 168 h. Soil pH and NH4+-N concentration increased at two and six months following the wildfire. In contrast, soil organic matter content decreased at two months post wildfire which, in combination of abiotic conditions such as low moisture content (<3.3%), resulted in reduced soil microbial biomass and enzyme activity. Increased soil moisture six months post fire created more favorable conditions for nitrification resulting in increased NO3-N concentration (0.8 to 36.1 mg NO3-N kg−1 soil), particularly following high severity fire. Prescribed fire did not have lasting impacts on soil nutrients, but both prescribed and wildfire resulted in increased NH4+-N, shifts in microbial community structure and decreased in microbial biomass. While the increase in nitrogen maybe be beneficial to the plant growth and revegetation, the loss of microbial biomass may have far reaching implications to the overall sustainability of the soils in these systems.
  4. Brown, Julian, Alan York, and Fiona Christie. “Fire effects on pollination in a sexually deceptive orchid.” International Journal of Wildland Fire 25.8 (2016): 888-895. Research into the effectiveness of prescribed fire in managing pollination has only recently begun. The effects of fire on pollination have not been explored in sexually deceptive systems. Further, the potential for multiple effects operating at different spatial scales has not been explored in any pollination system despite multi-scale effects on pollination observed in agricultural landscapes. We observed the frequency of pollinator visitation to flowers of sexually deceptive Caladenia tentaculata and related it to the post-fire age class of the vegetation at local and landscape scales. We also related the number of the pollinator’s putative larval hosts (scarab beetles) captured at these sites to age class. At the local scale (i.e. the sample location), visitation was highest in recently burnt sites. At the landscape scale, positive associations were observed between (1) putative pollinator hosts and vegetation burnt 36–50 years ago, and (2) pollinator visitation and vegetation burnt ≥50 years ago. Local- and landscape-scale effects on visitation were synergistic, such that visitation was greatest when fire age was heterogeneous within pollinator foraging range.
  5. Alcañiz, M., et al. “Long-term dynamics of soil chemical properties after a prescribed fire in a Mediterranean forest (Montgrí Massif, Catalonia, Spain).” Science of the total environment 572 (2016): 1329-1335.  This study examines the effects of a prescribed fire on soil chemical properties in the Montgrí Massif (Girona, Spain). The prescribed forest fire was conducted in 2006 to reduce understory vegetation and so prevent potential severe wildfires. Soil was sampled at a depth of 0–5 cm at 42 sampling points on four separate occasions: prior to the event, immediately after, one year after and nine years after. The parameters studied were pH, electrical conductivity (EC), total carbon (C), total nitrogen (N), available phosphorus (P), potassium (K+), calcium (Ca2 +) and magnesium (Mg2 +). All parameters (except pH) increased significantly immediately after the fire. One year after burning, some chemical parameters – namely, EC, available P and K+ – had returned to their initial, or even lower, values; while others – pH and total C – continued to rise. Total N, Ca2 + and Mg2 + levels had fallen one year after the fire, but levels were still higher than those prior to the event. Nine years after the fire, pH, total C, total N and available P are significantly lower than pre-fire values and nutrients concentrations are now higher than at the outset but without statistical significance. The soil system, therefore, is still far from being recovered nine years later.
  6. Armas-Herrera, Cecilia M., et al. “Immediate effects of prescribed burning in the Central Pyrenees on the amount and stability of topsoil organic matter.” Catena 147 (2016): 238-244Prescribed burning is the deliberate application of fire under selected conditions to accomplish predetermined management objectives. It is generally accepted that controlled use of fire has neutral or even positive effects on soils due to its lower temperature, intensity and severity compared to wildfires. However, very few studies have examined the effects of prescribed burning of shrub vegetation in humid mountain areas on soil properties. The objective of this work was to determine the immediate effects of prescribed burning on the quality and biochemical stability of soil organic matter (SOM) in areas encroached by shrubs in the Central Pyrenees (NE Spain). Soil samples were sampled in triplicate immediately before and after burning from the Ah horizon at 0–1, 1–2 and 2–3 cm depths. We quantified the variations as a direct result of burning in (1) the SOM content, (2) the content and mineralization rates of labile and recalcitrant C pools as inferred from incubation assays (141 days), and (3) the soil biological activity related to C cycling (microbial biomass C and β-D-glucosidase activity). Nearly all the soil properties studied were significantly affected by fire, varying in terms of extent of the effect and the soil depth affected. The total soil organic C (SOC), C/N ratio, β-D-glucosidase activity, C-CO2 efflux and estimated content of labile SOC decreased significantly up to 3 cm depth. The total N and microbial biomass C were significantly affected only in the upper cm of the soil (0–1 cm). These results describe a short-term stronger impact of the prescribed fire on topsoil properties than usually reported. However, comparing these findings to other studies should be performed with caution because of the different environments considered in each case, as well as the differing soil thicknesses found in the literature, typically between 5 and 15 cm, which can lead to a dilution effect associated with the actual impacts of fire on soil properties. In this sense, the choice of a suitable soil thickness or sampling just after burning can be relevant factors in the detection of the immediate effects of fire. Short- and medium-term monitoring of the soils is needed to assess the suitability of this practice for pasture maintenance and for adapting the frequency of prescribed fires in order to minimize its impact on soil.
  7. Sun, Hui, et al. “Bacterial community structure and function shift across a northern boreal forest fire chronosequence.” Scientific reports 6 (2016): 32411Soil microbial responses to fire are likely to change over the course of forest recovery. Investigations on long-term changes in bacterial dynamics following fire are rare. We characterized the soil bacterial communities across three different times post fire in a 2 to 152-year fire chronosequence by Illumina MiSeq sequencing, coupled with a functional gene array (GeoChip). The results showed that the bacterial diversity did not differ between the recently and older burned areas, suggesting a concomitant recovery in the bacterial diversity after fire. The differences in bacterial communities over time were mainly driven by the rare operational taxonomic units (OTUs < 0.1%). Proteobacteria (39%), Acidobacteria (34%) and Actinobacteria (17%) were the most abundant phyla across all sites. Genes involved in C and N cycling pathways were present in all sites showing high redundancy in the gene profiles. However, hierarchical cluster analysis using gene signal intensity revealed that the sites with different fire histories formed separate clusters, suggesting potential differences in maintaining essential biogeochemical soil processes. Soil temperature, pH and water contents were the most important factors in shaping the bacterial community structures and function. This study provides functional insight on the impact of fire disturbance on soil bacterial community.
  8. Badía, David, et al. “Burn effects on soil properties associated to heat transfer under contrasting moisture content.” Science of the Total Environment 601 (2017): 1119-1128. The aim of this work is to investigate the topsoil thickness affected by burning under contrasting soil moisture content (field capacity versus air-dried conditions). A mollic horizon of an Aleppo pine forest was sampled and burned in the laboratory, recording the temperature continuously at the topsoil surface and at soil depths of 1, 2, and 3 cm. Changes in soil properties were measured at 0–1, 1–2, 2–3, and 3–4 cm. Both the maximum temperature and the charring intensities were significantly lower in wet soils than in air-dried soils up to 3 cm in depth. Moreover, soil heating was slower and cooling faster in wet soils as compared to dry soils. Therefore, the heat capacity increase of the soil moistened at field capacity plays a more important role than the thermal conductivity increase on heat transfer on burned soils. Burning did not significantly modify the pH, the carbonate content and the chroma, for either wet or dry soil. Fire caused an immediate and significant decrease in water repellency in the air-dried soil, even at 3 cm depth, whereas the wet soil remained hydrophilic throughout its thickness, without being affected by burning. Burning depleted 50% of the soil organic C (OC) content in the air-dried soil and 25% in the wet soil at the upper centimeter, which was blackened. Burning significantly decreased the total N (TN) content only in the dry soil (to one-third of the original value) through the first centimeter of soil depth. Soluble ions, measured by electrical conductivity (EC), increased after burning, although only significantly in the first centimeter of air-dried soils. Below 2 cm, burning had no significant effects on the brightness, OC, TN, or EC, for either wet or dry soil.
  9. Dove, Nicholas C., and Stephen C. Hart. “Fire reduces fungal species richness and in situ mycorrhizal colonization: a meta-analysis.” Fire Ecology 13.2 (2017): 37-65Soil fungal communities perform many functions that help plants meet their nutritional demands. However, overall trends for fungal response to fire, which can be especially critical in a post-fire context, have been difficult to elucidate. We used meta-analytical techniques to investigate fungal response to fire across studies, ecosystems, and fire types. Change in fungal species richness and mycorrhizal colonization were used as the effect size metrics in random effects models. When different types of methods for assessing fungal species richness and mycorrhizal colonization were considered together, there was an average reduction of 28 % in fungal species richness post fire, but no significant response in mycorrhizal colonization. In contrast, there was a 41 % reduction in fungal species richness post fire when assessed by sporocarp surveys, but fungal species richness was not significantly affected when assessed by molecular methods. Measured in situ, fire reduced mycorrhizal colonization by 21 %, yet no significant response occurred when assessed by ex situ bioassays. These findings suggest that the putative magnitude of fire effects on soil fungal communities may be dependent on the approach and assessment method used. Furthermore, biome, but not fire type (i.e., wildfire versus prescribed fire) was a significant moderator of our categorical models, suggesting that biome might be a more useful predictor of fungal species richness response to fire than fire type. Reductions in fungal species richness and in situ mycorrhizal colonization post fire declined logarithmically and approached zero (i.e., no effect) at 22 and 11 years, respectively. We concluded that fire reduces fungal species richness and in situ mycorrhizal colonization, but if conditions allow communities to recover (e.g., without subsequent disturbance, favorable growing conditions), soil fungi are resilient on decadal time scales; the resiliency of soil fungi likely contributes to the overall rapid ecosystem recovery following fire.
  10. Girona-García, Antonio, et al. “Effects of prescribed burning on soil organic C, aggregate stability and water repellency in a subalpine shrubland: Variations among sieve fractions and depths.” Catena 166 (2018): 68-77Soil organic matter, aggregation and water repellency are relevant interrelated soil properties that can be affected by fire. The aim of this work was to analyse the effects of shrub prescribed burning for pasture reclamation on the soil aggregate stability, organic carbon and water repellency of different soil depths and aggregate sizes in a subalpine environment. Soil samples were collected from an area treated by an autumnal low-intensity prescribed fire in the Central Pyrenees (NE-Spain) at 0–1, 1–2, 2–3 and 3–5 cm depths just before and ~1 h, 6 months and 12 months after burning. Samples were separated as whole soil (<10 mm) and 6 sieve fractions, <0.25, 0.25–0.5, 0.5–1, 1–2, 2–4 and 4–10 mm. We analysed soil organic Carbon (SOC), aggregate stability (AS) and soil water repellency (SWR). In the unburned samples, SOC and SWR were higher in the <0.25 to 2 mm sieve fractions than the 2 to 10 mm sieve fractions. Fire severely and significantly decreased the SOC content in the whole soil and the <0.25 mm fraction at 0–1 cm depth and in the 0.25–0.5 mm fraction at 0–2 cm depth. SWR was reduced by burning mainly at 0–1 cm depth for the whole soil and the <0.25 to 2 mm sieve fractions. Nevertheless, the AS of the 0.25–0.5 mm aggregates increased after fire, while the rest of the sieve fractions remained virtually unaffected. One year after the prescribed burning, SOC slightly increased and SWR recovered in the fire-affected fractions, while the AS for all aggregate sizes and depths showed a considerable decrease. The results suggest that the direct effects of burning are still present one year after burning, and the post-fire situation may pose an increased risk of soil loss. Furthermore, our results indicate that fine soil fractions are more likely to be affected by fire than coarser soil fractions and highly influence the whole soil behaviour.
  11. Butler, Orpheus M., et al. “The phosphorus‐rich signature of fire in the soil–plant system: a global meta‐analysis.” Ecology letters 21.3 (2018): 335-344.  The biogeochemical and stoichiometric signature of vegetation fire may influence post‐fire ecosystem characteristics and the evolution of plant ‘fire traits’. Phosphorus (P), a potentially limiting nutrient in many fire‐prone environments, might be particularly important in this context; however, the effects of fire on Phosphorus   cycling often vary widely. We conducted a global‐scale meta‐analysis using data from 174 soil studies and 39 litter studies, and found that fire led to significantly higher concentrations of soil mineral Phosphorus as well as significantly lower soil and litter carbon:Phosphorus  and nitrogen:Phosphorus ratios. These results demonstrate that fire has a Phosphorus ‐rich signature in the soil–plant system that varies with vegetation type. Further, they suggest that burning can ease Phosphorus limitation and decouple the biogeochemical cycling of Phosphorus , carbon and nitrogen. These effects resemble a transient reversion to an earlier stage of ecosystem development, and likely underpin at least some of fire’s impacts on ecosystems and organisms.
  12. Alcañiz, M., et al. “Effects of prescribed fires on soil properties: a review.” Science of The Total Environment 613 (2018): 944-957.  Soils constitute one of the most valuable resources on earth, especially because soil is renewable on human time scales. During the 20th century, a period marked by a widespread rural exodus and land abandonment, fire suppression policies were adopted facilitating the accumulation of fuel in forested areas, exacerbating the effects of wildfires, leading to severe degradation of soils. Prescribed fires had emerged as an option for protecting forests and their soils from wildfires through the reduction of fuels levels. However such fires can serve other objectives, including stimulating the regeneration of a particular plant species, maintaining biological diversity or as a tool for recovering grasslands in encroached lands. This paper reviews studies examining the short- and long- term impacts of prescribed fires on the physical, chemical and biological soil properties; in so doing, it provides a summary of the benefits and drawbacks of this technique, to help determine if prescribed fires can be useful for managing the landscape. From the study conducted, we can affirm that prescribed fires affect soil properties but differ greatly depending on soil initial characteristics, vegetation or type of fire. Also, it is possible to see that soil’s physical and biological properties are more strongly affected by prescribed fires than are its chemical properties. Finally, we conclude that prescribed fires clearly constitute a disturbance on the environment (positive, neutral or negative depending on the soil property studied), but most of the studies reviewed report a good recovery and their effects could be less pronounced than those of wildfires because of the limited soil heating and lower fire intensity and severity.
  13. Koltz, Amanda M., et al. “Global change and the importance of fire for the ecology and evolution of insects.” Current opinion in insect science 29 (2018): 110-116Climate change is drastically altering global fire regimes, which may affect the structure and function of insect communities. Insect responses to fire are strongly tied to fire history, plant responses, and changes in species interactions. Many insects already possess adaptive traits to survive fire or benefit from post-fire resources, which may result in community composition shifting toward habitat and dietary generalists as well as species with high dispersal abilities. However, predicting community-level resilience of insects is inherently challenging due to the high degree of spatio-temporal and historical heterogeneity of fires, diversity of insect life histories, and potential interactions with other global change drivers. Future work should incorporate experimental approaches that specifically consider spatiotemporal variability and regional fire history in order to integrate eco-evolutionary processes in understanding insect responses to fire.
  14. Pellegrini, Adam FA, et al. “Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity.” Nature 553.7687 (2018): 194. Fire frequency is changing globally and is projected to affect the global carbon cycle and climate. However, uncertainty about how ecosystems respond to decadal changes in fire frequency makes it difficult to predict the effects of altered fire regimes on the carbon cycle; for instance, we do not fully understand the long-term effects of fire on soil carbon and nutrient storage, or whether fire-driven nutrient losses limit plant productivity. Here we analyse data from 48 sites in savanna grasslands, broadleaf forests and needleleaf forests spanning up to 65 years, during which time the frequency of fires was altered at each site. We find that frequently burned plots experienced a decline in surface soil carbon and nitrogen that was non-saturating through time, having 36 per cent (±13 per cent) less carbon and 38 per cent (±16 per cent) less nitrogen after 64 years than plots that were protected from fire. Fire-driven carbon and nitrogen losses were substantial in savanna grasslands and broadleaf forests, but not in temperate and boreal needleleaf forests. We also observe comparable soil carbon and nitrogen losses in an independent field dataset and in dynamic model simulations of global vegetation. The model study predicts that the long-term losses of soil nitrogen that result from more frequent burning may in turn decrease the carbon that is sequestered by net primary productivity by about 20 per cent of the total carbon that is emitted from burning biomass over the same period. Furthermore, we estimate that the effects of changes in fire frequency on ecosystem carbon storage may be 30 per cent too low if they do not include multidecadal changes in soil carbon, especially in drier savanna grasslands. Future changes in fire frequency may shift ecosystem carbon storage by changing soil carbon pools and nitrogen limitations on plant growth, altering the carbon sink capacity of frequently burning savanna grasslands and broadleaf forests. CONCLUSION: In conclusion, our results reveal the sensitivity of surface soils to fire and the substantial effects that changes in soil pools have on long-term ecosystem C exchange. The large empirical and conservative modelbased
    estimates of soil C changes suggest that present estimates of fire-driven C losses7, which primarily consider losses from plant biomass pools, may substantially underestimate the effects of long-term trends in fire frequencies in savanna grasslands and broadleaf forests in particular. Our findings suggest that future alterations in fire regimes in savanna grasslands and broadleaf forests may shift ecosystem C storage by changing soil C levels and changing the N limitation of plant growth, altering the carbon-sink capacity of these fire-prone ecosystems.
  15. Pressler, Yamina, John C. Moore, and M. Francesca Cotrufo. “Belowground community responses to fire: meta‐analysis reveals contrasting responses of soil microorganisms and mesofauna.” Oikos 128.3 (2019): 309-327Global fire regimes are shifting due to climate and land use changes. Understanding the responses of below-ground communities to fire is key to predicting changes in the ecosystem processes they regulate. We conducted a comprehensive meta‐analysis of 1634 observations from 131 empirical studies to investigate the effect of fire on soil microorganisms and mesofauna. Fire had a strong negative effect on soil biota biomass, abundance, richness, evenness, and diversity. Fire reduced microorganism biomass and abundance by up to 96%. Bacteria were more resistant to fire than fungi. Fire reduced nematode abundance by 88% but had no significant effect on soil arthropods. Fire reduced richness, evenness and diversity of soil microorganisms and mesofauna by up to 99%. We found little evidence of temporal trends towards recovery within 10 years post‐disturbance suggesting little resilience of the soil community to fire. Interactions between biome, fire type, and depth explained few of these negative trends. Future research at the intersection of fire ecology and soil biology should aim to integrate soil community structure with the ecosystem processes they mediate under changing global fire regimes.

 

 

This post was motivated by a related post on the WUWT site [LINK] .