The East Siberian Arctic Shelf is a significant source of atmospheric methane as referred from multi-year ship-based observations (2000-2015)

Abstract:

According to NOAA/CMDL data, the highest concentration and greatest seasonal amplitudes of atmospheric methane (CH₄) occur at 60–70N, outside the 30–60N band where the main sources of anthropogenic CH₄ is located, indicating that the northern environment is a source of these gases. Analyses of ice core samples also suggest a strong pole-to-pole gradient existing during inter-glacial epochs back to preindustrial times, which is independent of anthropogenic activity. The global budget of CH₄ established >40 years ago, when very little knowledge existed about Arctic terrestrial sources and nothing was known about Arctic marine sources, has never considered contribution of Arctic sources of CH₄ adequately. Here we present results of the multiyear high-precision continuous measurements across the Barents Sea, the Kara Sea, the Laptev Sea, the East Siberian Sea, the Chukchi Sea, the Bering Sea, the Sea of Okhotsk and the Japan Sea performed during one expedition in each of two years (2011 and 2012). Results of our investigations demonstrate that concentrations of dissolved CH₄ measured in the surface water in all 8 seas were supersaturated regards to the atmosphere. However, anomalously high concentrations of dissolved CH4 in the surface water (up to 5,000-12,000% of super-saturation) was found in the East Siberian Arctic Shelf, which is composed of the Laptev Sea, the East Siberian Sea and the Chukchi Sea.