Previous projections suggested stability of ice- and organic-rich permafrost in northeast Siberia beyond 2100, even under pessimistic warming scenarios. However, these projections lacked thermokarst processes. This study incorporates thermokarst into a numerical model and projects substantial permafrost degradation under strong warming (RCP8.5), while moderate warming (RCP4.5) shows thawing moderated by stabilizing feedbacks. Thaw-affected carbon by 2100 could be up to three-fold (RCP4.5) or twelve-fold (RCP8.5) higher than projections ignoring thermokarst. The study highlights the need for improved Earth system models to accurately assess global permafrost carbon-climate feedback and emphasizes climate change mitigation.

Jan Nitzbon, Sebastian Westermann, Moritz Langer, Léo C. P. Martin, Jens Strauss, Sebastian Laboor, Julia Boike