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Arctic Sea Ice Weirdness: Chukchi Sea

Posted on: November 21, 2019

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.  

 

[LINK TO HOME PAGE OF THIS SITE]

 

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.

 

 

 

 

 

 

 

 

 

 

3 Responses to "Arctic Sea Ice Weirdness: Chukchi Sea"

POSTED 11/24/2019 THAILAND TIME

[…] active region of the planet not unlike the Ring of Fire in the Pacific [LINK] [LINK] [LINK] [LINK] and that the observed changes in September minimum sea ice extent does not cannot be related to AGW […]

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