Sources of methane for the atmosphere along the West Antarctic Peninsula at the end of Austral summer

Methane is the second most important greenhouse gas in the atmosphere. It also has a global warming potential 30 times higher than CO2 over a 100-year period. But there are still uncertainties about the methane budget and the ocean contribution to it. Especially the polar regions, due to a lack of data, mainly because of the remote nature of the area. Our study focuses on methane concentration along the atmosphere-sea ice-water column-sediment continuum in shallow areas of the West Antarctic Peninsula (WAP) during the end of Austral summer. The main goal is to constrain methane sources and sinks in those areas to better understand each compartment's contribution to the atmosphere. Our study provides evidence that the WAP is a source of methane to the atmosphere, with saturation ranging from 98% up to 3000%. The sources of methane are diverse and can be multiple at a given location, leading to water-column oversaturation. One of the highlights of this research is the evidence of a methane source from subglacial meltwater, which has been observed in the Arctic but not yet in the Antarctic. Sediment remains an important source, with mean fluxes of 1.40 ± 2.59 mmol*m-2*d-1 going from the sediment to the water column. This study is contributing to a better understanding of methane processes in the West Antarctic Peninsula and the types of sources present.