Researchers at ETH Zurich have now discovered for the first time that large blackwater lakes in the extensive peatlands of the central Congo Basin are releasing ancient carbon. To date, climate researchers had assumed that carbon was stored safely for millenia in the peat. How the carbon is mobilized from the peat to the lake, where it is finally released to the atmosphere, is still unknown. Climate changes and altered land use, especially the conversion of forest to cropland, could exacerbate this trend—with consequences for the global climate.