SHAKHOVA. Natalia Shakhova, Igor Semiletov et al (Russian scientists) (2015), “The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice” Sustained release of methane (CH4) to the atmosphere from thawing Arctic permafrost may be a positive and significant feedback to climate warming. Atmospheric venting of CH4 from the East Siberian Arctic Shelf (ESAS) was recently reported to be on par with flux from the Arctic tundra; however, the future scale of these releases remains unclear. Here, based on results of our latest observations, we show that CH4 emissions from this shelf are likely to be determined by the state of subsea permafrost degradation. We observed CH4 emissions from two previously understudied areas of the ESAS: the outer shelf, where subsea permafrost is predicted to be discontinuous or mostly degraded due to long submergence by seawater, and the near shore area, where deep/open taliks presumably form due to combined heating effects of seawater, river run-off, geothermal flux and pre-existing thermokarst. CH4 emissions from these areas emerge from largely thawed sediments via strong flare-like ebullition, producing fluxes that are orders of magnitude greater than fluxes observed in background areas underlain by largely frozen sediments. We suggest that progression of subsea permafrost thawing and decrease in ice extent could result in a significant increase in CH4 emissions from the ESAS… Sea ice serves as a natural physical barrier that restricts CH4 emissions from the ESAS during the ice-covered period. Because the temperature in the Arctic has increased at twice the rate as in the rest of the globe, and the region is expected to increase an additional 8°C (14°F) in the twenty-first century [3], longer periods of open water and shorter ice-covered periods [35,36] are occurring. Increasing periods of open water implies an increasing number of storm events, when wind speed increases to 15 m s−1 or more and the boundary between sea surface and air increases many times due to deep water mixing. Such events have the potential to rapidly ventilate bubble-transported and dissolved CH4 from the water column, producing high emission rates to the atmosphere. Because more than 75% of the total ESAS area is less than 50 m in depth, the water column provides bubbles with a very short conduit to the atmosphere. Storms enable more CH4 release because they destroy shallow water stratification and increase the boundary between sea surface and air, thus increasing gas exchange across phase boundaries. As a result, bubble-mediated, storm-induced CH4 ‘pulses’ force a greater fraction of CH4 to bypass aqueous microbial filters and reach the atmosphere [10]. In addition, about 10% of the ESAS remains open water in winter due to formation of flaw polynyas. It was shown that flaw polynyas provide pathways for CH4 escape to the atmosphere during the arctic winter [37]. Areas of flaw polynyas in the ESAS increased dramatically (by up to five times) during the last decades, and now exceed the total area of the Siberian wetlands (electronic supplementary material, figure S5). This implies that the ESAS remains an active source of CH4 to the atmosphere year-round. Increasing storminess [38–40] and rapid sea-ice retreat [36] causing increased CH4 fluxes from the ESAS are possible new climate-change-driven processes. Continuing warming of the AO will strengthen these processes, and the role of the ESAS as a year-round contributor to global CH4 emissions will grow over time” (see Natalia Shakhova, Igor Semiletov et al, ““The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice”, Royal Society Philosophical Transactions A, 7 September 2015: http://rsta.royalsocietypublishing.org/content/373/2052/20140451 ).