Ebullition-driven fluxes of methane from shallow hot spots suggest significant under-estimation of annual emission from the East Siberian Arctic Shelf

The high-latitude, shallow ESAS has been alternately subaerial and inundated with seawater during glacial and interglacial periods respectively. Subaerial conditions foster the formation of permafrost and associated hydrate deposits whereas inundation with relatively warm seawater destabilizes the permafrost and hydrates. Our measurements of CH4 in 1994-2000 and 2003-2010 over ESAS demonstrate the system to be in a destabilization period. First estimates of ESAS methane emissions indicated the current atmospheric budget, which arises from gradual diffusion and ebullition, was on par with estimates of methane emissions from the entire World Ocean (≈8 Tg-CH4). Large transient emissions remained to be assessed; yet initial data suggested that component could increase significantly annual emissions. New data obtained in 2008-2010 show that contribution of ebullition-driven CH4 fluxes from shallow hot spots alone could multiply previously reported annual emission from the entire ESAS.