Work

Divergent controls on surface and thermal offsets in permafrost across the three poles

Year: 2025

Type: article

Abstract: The thermal response of permafrost to climate change is quantified by two key metrics: the surface offset ( SO ), the mean annual temperature difference between near-surface air and the ground surface, and the thermal offset ( TO ), the equivalent difference between the ground surface and the top of permafrost. However, a comprehensive global synthesis of their magnitude, variability, and controlling drivers remains elusive. Here, synthesizing data from 117 sites across the three poles, we reveal a fundamental, scale-dependent decoupling of their controls. We show that SO is primarily controlled by large-scale climate, with precipitation dictating the similar large magnitude of SO in the Arctic (3.1 ± 0.3 °C, cold-humid permafrost) and the Third Pole (3.2 ± 0.2 °C, warm-dry permafrost), but small in Antarctica (1.0 ± 0.2 °C, ultraxerous permafrost). In contrast, TO is predominantly determined by local-scale substrate properties, being markedly negative in the Arctic (−0.5 ± 0.2 °C), weakly negative in the Third Pole (−0.2 ± 0.1 °C), and negligible in Antarctica (−0.1 ± 0.1 °C). Critically, this substrate control can be overridden by regional climate, such as advective heat transport following rainfall. This synthesis establishes the first global benchmarks for permafrost thermal states and reveals a paradigm of divergent, multi-scale controls essential for improving models that predict the fate of Earth’s thawing cryosphere.

Source: npj Climate and Atmospheric Science

DOI: 10.1038/s41612-025-01235-1