Permafrost Degradation Modulates Recent Silicate Chemical Weathering Records in East Siberian Arctic Shelf Sediments

As the Arctic rapidly warms, permanently frozen ground — a mixture of ice and soil — begins to thaw. This can cause soil particles to react with water and air, potentially influencing atmospheric CO₂ levels and thus climate change. We analyzed seafloor sediments from the Siberian coast to understand how thawing permafrost affects these reactions over recent decades. Our findings reveal a two-stage process. During early thaw, exposure of fresh mineral surfaces and infiltration of meltwater do enhance chemical weathering. However, as thawing intensifies, widespread ground collapse (thermokarst) accelerates erosion, sending large amounts of rock fragments rapidly to the ocean. Different regions, with different permafrost coverage and at different stages of thaw, show different weathering trends. These findings contribute to our understanding of how Arctic warming drives a suite of related earth surface processes that ultimately influence climate change. They also reveal a new pathway: weakly weathered materials continue reacting with seawater on the seafloor, shaping the Arctic carbon cycle.