Ancient Peatland "Leak" Discovered in Congo Basin Lakes Releasing Thousands of Years of Stored Carbon

ETH Zurich researchers find Congo Basin blackwater lakes are releasing 2,000-year-old carbon, signaling a potential leak in one of Earth's largest carbon sinks.

By: AXL Media

Published: Feb 24, 2026, 8:21 AM EST

Source: The information in this article was sourced from ETH Zurich

Mapping the Hidden Flux of Tropical Carbon Sinks

The Congo Basin, home to the world’s most extensive tropical peatland complex, holds approximately one-third of all carbon stored in such ecosystems globally. Despite covering only 0.3% of the Earth's surface, these swamps and forests represent a massive terrestrial battery of organic matter. Researchers from ETH Zurich, navigating the remote and difficult-to-access Lac Mai Ndombe, have identified a significant transfer of this stored energy into the atmosphere. According to the study published in Nature Geoscience, these blackwater lakes act as conduits, releasing carbon that has been sequestered for millennia.

Radiocarbon Dating Uncovers Ancient Emissions

By utilizing radiocarbon dating on the CO₂ dissolved in the dark, tea-colored waters of Lake Mai Ndombe, the research team discovered a "leak" in the reservoir. While scientists expected the emissions to stem from recently decomposed plant matter, the results showed that 40% of the carbon originated from ancient peat layers. According to lead author Travis Drake, this finding is a significant departure from the traditional understanding that peat-bound carbon remains stable unless disturbed by extreme events like severe droughts.

Microbial Activity and the Methane Balance

Beyond carbon dioxide, the study investigated the emission of methane, a potent greenhouse gas, and found its release is heavily dictated by seasonal water levels. During periods of high water, specialized microorganisms are more effective at breaking down methane before it reaches the surface. However, according to Professor Jordon Hemingway, lower water levels during the dry season significantly reduce this microbial filtration, allowing larger quantities of methane to escape. This suggests that the region's climate impact is highly sensitive to hydrological shifts.