Satellite Ice Extent, Sea Surface Temperature, Chlorophyll, and Atmospheric Methane Trends in the Barents and Kara Seas

Over a decade (2003-2015) of sea-ice extent, sea surface temperature (SST), and lower tropospheric methane satellite data were analyzed for statistically-significant anomalies and trends in the Barents and Kara Seas (BKS), at the pixel and focus area scales. Large positive methane anomalies were discovered around Franz Josef Land (FJL) and offshore west Novaya Zemlya (methane increased at 3.06 to 3.49 ppb yr-1). The southeast Barents Sea, south Kara Sea, and coastal areas around FJL exhibited the strongest BKS methane growth.SST increased 0.0018 to 0.15°C yr -1 with fastest increase in the southeast Barents Sea in June. This is due to the seasonal strengthening of the warm Murman Current and the transport of increasingly warmer waters from the North Atlantic. The greatest Kara Sea SST growth was in September. Likely sources of the increasing tropospheric methane include seepage from subsea permafrost and hydrates and petroleum reservoirs under the central and east Barents Sea and the Kara Sea. While the atmospheric methane growth’s spatial pattern poorly matched seabed depth, increasing methane may relate to advection of warm, methane-laden bottom waters into shallower waters (enhancing ventilation of methane-rich bottom waters) and from seasonal mixed layer deepening. he strongest fall chlorophyll growth was between the edge of the Central Bank and the Barents Sea Polar Front where upwelling is likely. Chlorophyll and methane growth were co-located in the southeast Barents Sea where currents upwell bottom waters. Trends suggest an ice-free Barents Sea around 2030, which will increase BKS methane emissions