Methane Emissions and Dynamics in the Weddell and Scotia Seas

Abstract

The Southern Ocean's role in the global methane ((Formula presented.)) cycle remains uncertain due to limited measurement data from this remote region. It is unclear if the Southern Ocean acts as a source or sink of atmospheric (Formula presented.), and climatic changes can have consequences on the amount of marine (Formula presented.) released due to the acceleration of glacial melting and uncertain consequences on seabed (Formula presented.) reservoirs. Monitoring (Formula presented.) here is essential to understanding its impact on the global (Formula presented.) budget now and in the future. This study measured (Formula presented.) concentrations in both ocean and atmosphere during an expedition in the Scotia Sea, Weddell Sea, and South Georgia shelf, linking seabed activity, water column concentrations, sea-air fluxes, and atmospheric (Formula presented.) levels. All areas were found to be a small source of (Formula presented.) to the atmosphere. Surface water (Formula presented.) concentrations of off-shelf waters were found to be lower south of the Southern Antarctic Circumpolar Current front, where upwelling brings (Formula presented.) -depleted waters to the surface. On-shelf regions show higher (Formula presented.) emissions compared to off-shelf, with average sea-air (Formula presented.) fluxes of 0.269 (Formula presented.) 0.035 μmol m−2 d−1 and 0.136 (Formula presented.) 0.021 μmol m−2 d−1, respectively, likely due to seabed seepage and methane-enriched freshwater. This study finds that the Weddell and Scotia seas (including the South Georgia shelf) are a small source of atmospheric (Formula presented.). As this result contradicts previous studies identifying this area as a (Formula presented.) sink, continued monitoring is needed to understand how emissions are changing and may continue to change in the future.