New research challenges the long-held assumption that carbon stored in tropical peatlands in the Congo Basin would not be released into the atmosphere for thousands of years to come.
Scientists have discovered that vast peatlands in Central Africa, long considered stable reserves of carbon, are releasing ancient carbon into the atmosphere.
A Congo Basin it is home to one of the largest tropical peatland systems in the world. Although these peatlands cover just 0.3% of the Earth’s surface, they store approximately a third of all the carbon contained in tropical peatlands. For decades, researchers assumed this carbon was stored safely for thousands of yearsunless extreme conditions, such as prolonged drought, disrupt the ecosystem, says .
New research led by scientists at ETH Zurich challenges this assumption. In one published in Nature Geoscience, researchers examined two murky “blackwater” lakes—Lac Mai Ndombe and Lac Tumba—whose tea-colored waters are rich in organic matter from the surrounding peat-rich swamp forests. Measurements revealed that significant amounts of carbon dioxide are escaping from these lakes to the atmosphere.
Surprisingly, radiocarbon dating has shown that up to 40% of the carbon dioxide emitted comes from peat accumulated thousands of years agonot from plants that have recently grown. The discovery suggests that ancient carbon reservoirs in the Congo Basin are already “leaking,” even without clear evidence of significant drought-driven peat collapse. It is not yet clear how this ancient carbon moves from the deep layers of peat into the lake water, and scientists continue to investigate whether the process represents a destabilizing change or a natural cycle balanced by the formation of new peat.
The study also points to future climate risks. Drier conditions can allow oxygen to penetrate deeper into peat soils, accelerating microbial decomposition and releasing even more carbon dioxide.
Human pressures can worsen these threats. Population growth and deforestation in the region could intensify dryness, reducing forest-driven moisture recycling, which could keep lake levels persistently low. Researchers warn that such changes could transform the swamps of the Congo Basin into important sources of greenhouse gases.
