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.