This study addresses the fate of permafrost carbon mobilised by retrogressive thaw slumps, one of the most dynamic forms of abrupt Arctic permafrost degradation. Because permafrost carbon feedbacks represent a key uncertainty in climate change projections, improved constraints on the age and stability of thaw-mobilised carbon are of broad scientific relevance. By linking activation energy distributions with thermally resolved radiocarbon measurements, the authors provide a mechanistic perspective on the stability of particulate carbon exported from thaw slumps, offering insights that will be of interest to the wider geoscience community working on Arctic carbon cycling and climate feedbacks.

Coastal marshes play an important role in climate regulation and ecosystem services. This study provides the first large-scale assessment of carbon storage in Nordic coastal marshes, a region currently underrepresented in global blue carbon datasets. It shows how grazing management and environmental conditions jointly influence carbon storage and vegetation structure.

This study demonstrated, through an ocean alkalinity enhancement (OAE) experiment using mesocosms, that higher pH levels can reduce the ratio of biogenic silica to particulate organic carbon in sinking particles by promoting the dissolution of diatom-derived silica in seawater. Higher pH conditions might also cause organic carbon produced by diatoms to be remineralized at shallower depths, thereby reducing its ocean residence time and weakening the biological carbon pump for sequestering atmospheric carbon dioxide. This study also provides valuable insights into the linkage between OAE and biogeochemical processes in the ocean.