Convection in the active layer speeds up permafrost thaw in coarse-grained soils

Permafrost thaw plays a crucial role in climate change dynamics, yet the intricate small-scale processes driving thawing remain inadequately understood. Here we reveal that the density anomaly of water has the potential to trigger convection in coarse-grained soils above permafrost. By using high-resolution numerical simulations of the primitive equations in porous media we show that convection significantly accelerates the thawing process. Climate models that predominantly account for thawing induced by diffusive processes alone overlook this aspect, which can self-reinforce and lead to enhanced climate-permafrost feedback.