Recent Increase of Greenhouse Gas Emissions from Cryosphere-Influenced Reservoirs under Climate Change.

Abstract

Global warming leads to cryosphere degradation, transferring large amounts of terrestrial carbon and nitrogen to reservoirs, which may accelerate the release of greenhouse gases (GHGs) to the atmosphere. However, the spatial dynamics and decadal trends of GHG emissions from these reservoirs remain elusive. Here we compile a comprehensive data set of CO2 (1108 measurements), CH4 (661) and N2O (313) concentrations to estimate that cryosphere-influenced reservoirs emit 56.7 ± 9.3 Tg CO2 eq yr-1 of GHGs. Cryosphere-influenced reservoirs account for less than 10% of the global reservoir area, yet they contribute disproportionately high levels of CO2 and N2O emissions. Between 2000 and 2020, total emissions from cryosphere-influenced reservoirs increased significantly by 0.31 ± 0.11 Tg CO2 eq yr-1, which were mainly caused by climate warming and resultant cryosphere melt and thaw. This study highlights that, in contrast to the declining GHG emission trends observed in other reservoirs worldwide with little cryosphere impacts, emissions from cryosphere-influenced reservoirs are on the rise. This represents a growing and critically underappreciated source of anthropogenic GHGs under climate change.