Alarming decline in the carbon sink of European forests driven by disturbances.

Forests are carbon sinks essential for climate change mitigation. However, increased harvests and natural disturbances across Europe have recently challenged this role. To project the future carbon sink capacity of Europe's forests, we integrated country reports from the United Nations Framework Convention on Climate Change with remote sensing maps of disturbances and above-ground biomass. Our model simulates biomass dynamics at 18 km resolution from 2010 to 2030, predicting a 39% decrease in the EU-27 forest carbon sink, driven by disturbances outpacing biomass recovery. Consequently, the 2030 forest carbon sink will fall 27% short of the estimated target consistent with EU-27 climate objectives. We demonstrate that the three billion trees initiative is insufficient for climate change mitigation and needs to be combined with a 28% reduction in forest harvests from 2025 to 2030 to meet these targets.