No respite from permafrost-thaw impacts in absence of a global tipping point

Arctic permafrost, the largest non-seasonal component of Earth’s cryosphere, contains a significant climate-sensitive carbon pool. Its potential for loss due to climatic changes leading to a global tipping point, where thawing accelerates with disproportionate impacts, remains debated. Here, we provide an integrative perspective on this question, building on a cross-disciplinary meta-analysis of literature supported by geospatial analyses of global data products and climate model output. Contrary to the existence of a global-scale tipping point, scientific evidence suggests a quasi-linear response to global warming, both from observation-based and model-based projections. While certain processes, such as talik development, thermokarst, thermo-erosion, and vegetation interactions, can drive rapid local permafrost thaw and ground ice loss, they do not accumulate to a non-linear response beyond regional scales. We conclude that there is no safety margin for Arctic permafrost where its loss would be acceptable. Instead, with each increment of global warming, more land areas underlain by permafrost will proportionally experience thaw, causing detrimental local impacts and global feedbacks.