Permafrost and wildfire carbon emissions indicate need for additional action to keep Paris Agreement temperature goals within reach
First-of-its kind analysis integrating three types of biological emissions from permafrost ecosystems – gradual thickening of seasonally-thawed soil, abrupt permafrost thaw, and intensifying fire regimes.
Research link: Communications Earth & Environment (2026)
Rapid Arctic warming is thawing carbon-rich permafrost, releasing greenhouse gases that accelerate climate change. Despite the importance of this feedback, permafrost-enabled global-scale models simulate only gradual, top-down thickening of the seasonally-thawed soil. This ignores abrupt permafrost thaw and intensifying fire regimes that combust soil carbon and further accelerate thaw.
This study expands a leading compact Earth system model (OSCAR v3.0), enabling initial estimates of the impacts of abrupt thaw and wildfire, together with gradual thaw, on remaining carbon budgets consistent with the temperature goals of the Paris Agreement. OSCAR, which is built on four Land Surface Models (LSMs), is extended by adding new modules to simulate abrupt permafrost thaw emissions from below-ground combustion (above-ground combustion is already represented in OSCAR), and post-fire-induced permafrost thaw.
These new modules build on published observational studies and combine process-based understanding, projected changes in disturbance frequency, and syntheses of existing observational and experimental data. The new model suggests that including permafrost thaw and fire-related carbon emissions reduces the remaining allowable carbon budgets from 2025 onward by 25 % ± 12 % for avoiding 1.5 °C and 17 % ± 7 % for avoiding 2.0 °C, relative to simulations without these processes. Accounting for these additional emissions is critical for setting emissions reduction targets aligned with the Paris Agreement.
Lead researcher: Christina Schädel, Woodwell Climate Research Center (WCRC)
Contributing authors: Thomas Gasser (WCRC), Brendan Rogers (WCRC), Rachael Treharne (WCRC), Merritt Turetsky (U Colorado Boulder), Trevor Smith (WCRC), Erin MacDonald (WCRC), Susan Natali (WCRC)