Permafrost Thaw Could Cause Northern High Latitudes to Become a Net Carbon Source

Earth System Dynamics, 30 June 2026

Northern high latitude ecosystems above 50°N currently serve as an important carbon sink, storing at least twice the amount of carbon in the atmosphere within boreal forests, tundra, permafrost, and soils. As temperatures rise, thawing permafrost releases increasing amounts of carbon dioxide and methane, and may ultimately cause this region to become a net source of emissions. Researchers examined when this sink-to-source transition could occur using an advanced Earth system model that simulates permafrost, vegetation, and wildfire processes under a range of future emissions scenarios. In a low emissions scenario, permafrost carbon emissions increase the risk of northern high latitudes becoming a net carbon source by more than 50% at 2°C of warming. Importantly, overshoot scenarios further reduce the ability of this region to sequester carbon by providing less optimal conditions for vegetation growth as temperatures begin to decline after reaching a peak temperature. Wildfires also weaken the resilience of this region to warming, reducing its ability to act as a carbon sink. The study highlights the importance of minimizing temperature overshoot and the need to incorporate permafrost, vegetation, and wildfire feedbacks into the Earth system models used to estimate the remaining carbon budget left to achieve the goals of the Paris Agreement.

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