Variable effects of climate change on carbon balance in northern ecosystems

Abstract

Accumulation of carbon dioxide (CO2) and methane (CH4) in the atmosphere of the planet accelerates climate change, and northern high-latitude regions are warming faster than the planetary average. This accelerated warming of northern regions is associated with multiple climate feedbacks, including those linked to the mobilization of old organic carbon previously sequestered in the frozen ground. This critical climate-feedback mechanism has major uncertainties, and may respond nonlinearly to ongoing warming at high latitudes. This study examines the role of freshwater ecosystems in the subarctic carbon balance, and addresses some sources of nonlinearity in the effect of climate warming on these ecosystems. Specifically, I examine the CO2 and CH4 dynamics in permafrost thaw-related ecosystems, and the associated biogeochemical processes. Our results show that major sources of variation in the dynamics of these two gases are associated with the geomorphological properties of the landscape, the degree of ground warming and seasonal biogeochemical dynamics. Accelerated climate change in northern regions may also intensify the CO2 and CH4 cycles in these regions, and may substantially increase the current CH4 flux from these ecosystems.