Congo lakes are releasing ancient carbon, raising climate concerns, study says

Two large lakes in ​the Democratic Republic of Congo are releasing ​carbon that has been locked away ‌for thousands ​of years in surrounding peatlands, scientists said, in what could pose a threat to climate stability. Tropical peatlands, which play a crucial ‌role in climate regulation, were assumed to keep their carbon securely stored for millennia, according to researchers from the ETH Zurich university who published their findings in Nature Geoscience.

Two large lakes in ​the Democratic Republic of Congo are releasing ​carbon that has been locked away ‌for thousands ​of years in surrounding peatlands, scientists said, in what could pose a threat to climate stability.

Tropical peatlands, which play a crucial ‌role in climate regulation, were assumed to keep their carbon securely stored for millennia, according to researchers from the ETH Zurich university who published their findings in Nature Geoscience. However, the researchers from ‌ETH Zurich found that up to 40% of carbon dioxide emissions from Lakes Mai Ndombe ‌and Tumba come from ancient peat deposits, some over 3,000 years old, rather than recent plant matter.

"We were surprised to find that ancient carbon is being released via the lake," lead author Travis Drake said in a statement. "The ⁠carbon ​reservoir has a leak, ⁠so to speak, from which ancient carbon is escaping," co-author Matti Barthel said.

It is unclear how the carbon ⁠moves from peatlands into the lakes. Researchers say the phenomenon could worsen with climate change or changes ​in land use, such as the conversion of forest into cropland, which increases drought conditions. Peat, ⁠formed from the accumulation of dead plant material, does not decompose in a water-logged state but when it ⁠dries, the ​organisms that break down plant material revive and the carbon seeps back into the atmosphere.

The swamps and peatlands of the Congo Basin cover only 0.3% of the earth's ⁠land surface, yet hold one-third of the carbon stored in its tropical peatlands, positioning the region ⁠as a major carbon ⁠reservoir globally. It remains one of the world’s least-studied major forest regions, and researchers say far more work is needed to understand how its vast ‌ecosystems are ‌changing. (Reporting and writing by Clement Bonnerot, editing ​by Robbie Corey-Boulet, Alexandra Hudson)