New research using aerial imagery from 2012 to 2023 mapped more than 260 million dead trees within 10 kilometres of US coastlines and the Great Lakes. The study found that mortality tripled in low-lying coastal forests and doubled around expanding freshwater lakes and inland wetlands, pointing to rising water levels and waterlogging as the main drivers, not just saltwater intrusion. The findings complicate carbon accounting. Dead trees release carbon as they decompose, and if forests do not recover, the land may lose its ability to store carbon over the long term. But researchers note that wetland vegetation that replaces the forest could also accumulate carbon, so the net effect depends on how the landscape transitions. The study was published as a preprint on bioRxiv.
