Permafrost Carbon-Climate Feedback Increases Earth System Tipping Risks

Environmental Research Letters, 12 June 2026

Global warming leads to widespread permafrost thaw, releasing carbon dioxide and methane that drives further warming in a feedback cycle. Many models do not fully represent this feedback, which risks underestimating the threat of long-term warming impacts. This study investigates how this feedback affects the likelihood and timing of crossing tipping points in the Earth system under stabilization and temporary overshoot scenarios. Earth system tipping points are thresholds beyond which major components of the climate system – such as the polar ice sheets, ocean circulation, and the Amazon Rainforest – can undergo large and potentially irreversible changes. The study shows that the permafrost carbon-climate feedback leads to additional warming that increases the probability of crossing one or more tipping points by up to 50%. The feedback can also bring the timing at which these thresholds are crossed forwards by hundreds of years. The impact is particularly strong for the West Antarctic Ice Sheet and the Atlantic Meridional Overturning Circulation (AMOC), where including this permafrost feedback leads to earlier tipping. It is therefore essential to include the permafrost-carbon climate feedback when estimating future climate risks.

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