 The study uses a coupled hydrology biogeochemistry model to estimate changes in pan-arctic land-atmospheric methane and carbon dioxide exchanges under two climate change scenarios, considering water-table dynamics and permafrost flooring effects. The simulations indicate that terrestrial ecosystems act as a net GHG-sync of minus 0.2 PGCO2, EQYR-1, with CH4 emissions and CO2 uptakes projected to increase in response to warming climate, but the increasing rates depend on the scenario. Thorin-permafrost offsets about two-thirds of the accumulated GHG-sync over the century under the no-policy scenario, while nearly all CO2-induced GHG-sync through photosynthesis is undone by CH4-induced GHG source over the century. The study highlights the importance of increasing active layer depth in affecting soil carbon decomposition and methane emissions in response to future climate change. This article was offered by Su Dong-shu, Qian Lai-chuang, Xiong Dao, and others. We are article.tv, links in the description below.