The Congo Basin peatlands cover 0.3% of Earth's land surface and store roughly 100 gigatonnes of carbon — about one-third of all tropical peatland carbon globally. The carbon is old, accumulated over millennia under waterlogged conditions that suppress decomposition. The prevailing model treats these deposits as stable: carbon locked in place, removed from the active cycle, a vault.
Published in Nature Geoscience, Drake, Hemingway, and colleagues at ETH Zurich measured radiocarbon ages of dissolved inorganic carbon in Lac Mai Ndombe and Lac Tumba, Africa's largest blackwater lakes, sitting within these peatlands. The dissolved carbon is 2,170 to 3,515 radiocarbon years old. Up to 40% of the CO2 being emitted from these lakes originates not from recent plant decomposition but from ancient peat deposits that have been locked underground for millennia. The mechanism appears to be microbial respiration of old carbon within the peat, with the resulting CO2 transported into the lakes and outgassed to the atmosphere.
The structural insight is about the difference between a vault and a slow leak. The carbon was not released by a catastrophic event — no fire, no draining, no sudden disturbance. It is being mobilized continuously, at a rate invisible against the backdrop of the total stock but measurable in the isotopic composition of what the lakes exhale. The vault is not sealed. It has never been sealed. The question — whether the leak represents a natural equilibrium balanced by new peat formation, or a destabilizing pathway accelerated by warming — cannot be answered from the leak alone. But the leak's existence changes what the vault means. A hundred gigatonnes is either storage or a source, depending on the plumbing.