Implications of a warming Arctic - Methane emissions from submerged permafrost underlying the rapidly warming East Siberian Arctic Sea (Invited)

Methane (CH4) release from thawing Arctic permafrost is one of the few carbon-climate mechanisms that could change dramatically, forecast climate change in the near term. Submerged Arctic permafrost, such as underlies the vast East Siberian Arctic Sea (ESAS), is at particular risk due to rapidly warming oceans transferring heat to these deposits. Based on multibeam sonar surveys spanning thousands of kilometers, extensive methane bubble emissions across the ESAS have been documented. These bubble emissions are ubiquitous and in shallow water (< 50 m) depositing a fraction of the escaping gas into the water column with the rest directly escaping to the air. Multibeam sonar data was analyzed to estimate ebullition fluxes for the ESAS and compared well with a mass balance estimate based on 'storm ventilation' mass budget measurements. Maps of the spatial distribution of ebullition emissions correlated with warm riverine input, suggesting a new positive feedback system between warming climate and methane emissions. These inputs are mirrored in satellite methane column data.