The Central Congo Basin boasts the largest variety of tropical peatlands globally, covering 16.7 million hectares. Previously, radiocarbon dating of ancient peat was confined to just 14 samples, which poorly represented the area, indicating that peat development typically commenced during the Holocene. However, recent findings indicate that peat began forming in multiple locations during the late Pleistocene. The earliest date identified by the author is 42,300 years before present, highlighting that this peatland is one of the oldest in the world, twice as ancient as previously thought.

The central Congo Basin, which spans the equator, encompasses 360,000 km.² This wetland is shared by the Republic of the Congo and the Democratic Republic of the Congo.

Out of this wetland area, it is estimated that 167,600 km² have a median thickness of 1.7 m.

These peatlands rank among the most carbon-dense ecosystems worldwide, storing an average of 1712 mg c ha^-1 with a total of 29 pg c^-1 stored in peat.

Although research into the formation and expansion of this vast carbon reservoir is in its early stages, it includes studies on peat initiation and basin-wide development dynamics.

“These peat marshes serve as crucial global carbon reservoirs, equivalent to three years’ worth of fossil fuel emissions,” said Greta Dargie, a researcher from the University of Leeds.

“We now know that these are the oldest tropical peatlands on Earth.”

The research initiated with the team trekking through the inaccessible peat marshes of Congo, collecting peat samples up to 6 m deep on the forest floor using surgical tools.

Upon returning to the lab, they dated small samples of peat to ascertain when peat formation began at each sampling site.

Over a decade, researchers successfully collected and dated more than 50 cores from throughout the Central Congo Basin, reconstructing the development of the peatlands over time.

Scientists were surprised not only by the great age of these peatlands.

“One of our unexpected discoveries was that some of the older peatlands in central Congo started forming during periods when the region’s climate was considerably drier than today,” stated a researcher.

“The earlier hypothesis suggested that peat began forming in response to a wetter climate at the onset of the Holocene around 12,000 years ago.”

“We now understand that non-climatic factors must have helped saturate the soil enough for peat formation to occur.”

“This raises important questions about how climate change in the 21st century will impact peatland landscapes and the substantial carbon stored within them.”

The Congo Basin peat marshes provide essential resources for local communities, including fish, bushmeat, and building materials.

Due to their remoteness, these swamps also serve as crucial habitats for species such as forest elephants, Nile crocodiles, lowland gorillas, and bonobo chimpanzees.

While Congolese peatlands have largely avoided threats such as deforestation and drainage compared to many tropical regions, the push for improved local livelihoods and extraction of resources like oil can conflict with biodiversity and carbon conservation objectives.

Dr. Pauline Gulliver, a researcher at the University of Glasgow, remarked:

“These peatlands meticulously draw carbon from the atmosphere, safely storing it for at least 40,000 years.”

“The dynamics of peat cannot be understood within a timeframe that aligns with societal expectations.”

“If peatlands are compromised, they could release a significant amount of carbon into the atmosphere, worsening global warming.”

“It’s crucial to manage the carbon within the Congo Basin peatlands carefully to prevent such occurrences.”

Survey results were published in the journal Environmental Survey Letter.

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Greta C. Dargy et al. 2025. The timing of peat initiation throughout the central Congo Basin. environment. res. Rent 20, 084080; doi:10.1088/1748-9326/ade905