Large increase in atmospheric methane over West Siberian wetlands during summer detected from space

抄録

Although wetlands are the largest natural source of atmospheric methane, the amount and variability of methane emissions from wetlands still have large uncertainty. We investigated the local growth rate of the column-averaged methane dry air mole fraction (XCH₄) in Siberia where wetlands are widely abundant using 11-year (2009-2019) Greenhouse gases Observing SATellite (GOSAT) data. While the mean growth rate during the summer from the GOSAT observations is 7.2 ppb yr⁻¹ globally, that in West Siberia is 8.4 ppb yr⁻¹. In particular, the growth rates in West Siberia after 2013 is much larger in July and August than in the other months. Moreover, the growth of XCH₄ in West Siberia appears to larger than in the other boreal areas. These results imply that methane emissions from wetlands in West Siberia increased during the summer in recent several years.