Permafrost regions store vast amounts of organic carbon that are increasingly vulnerable to rapid environmental change. Abrupt permafrost thaw can rapidly remove vegetation cover and transfer substantial carbon to the atmosphere and aquatic systems. However, despite growing recognition of its importance, the distribution and evolution of abrupt thaw, and the controls on the magnitude, timing, and persistence of carbon release, lateral mobilization, and long-term sequestration remain poorly quantified and inadequately represented in current Earth System Models.

This session aims to bring together researchers across cryosphere science, geomorphology, biogeosciences, microbiology, hydrology, and ecology to advance understanding of abrupt permafrost thaw dynamics and its role as a potential driver of nonlinear carbon-cycle responses. We seek contributions that quantify abrupt thaw processes or characterize spatial hotspots or biogeochemical hot moments, using field observations, laboratory experiments, remote sensing, and modeling approaches to improve their representation in coupled landscape–biogeochemical models under a changing climate.

• B - Biogeosciences
• EP - Earth and Planetary Surface Processes
• GC - Global Environmental Change
• NH - Natural Hazards