By Betty Huang –
The Congo Basin, often referred to as the “lungs of Africa” and one of the world’s largest land-based carbon sinks, is releasing 1,000-year-old peat carbon into the atmosphere, according to a recent study published in Nature Geoscience. Stretching across six countries—Cameroon, Central African Republic, Democratic Republic of the Congo, Republic of the Congo, Equatorial Guinea, and Gabon—the Basin contains one of the world’s largest tropical peatland systems. These peatlands form when plants absorb carbon dioxide and later die in waterlogged, low-oxygen conditions where decomposition slows. Over time, partially decayed plant material accumulates as peat, locking carbon underground.
In studying Africa’s largest blackwater lake, Lac Mai Ndombe, along with the smaller Lac Tumba, researchers found that significant amounts of carbon dioxide (CO2) were outgassing into the atmosphere not only from recent plant life, but also from peat (partially decayed plant material) that has been locked away for thousands of years. Although the Basin’s peatlands cover just 0.3 percent of Earth’s land surface, they contain an estimated 30 billion metric tons of carbon, roughly one-third of all tropical peatland carbon. Altogether, this represents about twice the amount of carbon stored in all the world’s forests combined.
Of the CO2 emission from Lac Mai Ndombe and Lac Tumba, the study reported that up to 40 percent come from ancient peat. The researchers estimate that Lake Mai Ndombe alone may be releasing more than 150 gigagrams (Gg) of ancient carbon each year. The findings suggest that microbes within the peat break down long-stored carbon through respiration, producing CO₂ that moves through groundwater into the lakes and is then released into the atmosphere.
Peatlands remain effective carbon sinks because they absorb more carbon than they emit under stable, waterlogged conditions. While the Congo Basin remains relatively intact compared to heavily drained peatlands in Southeast Asia, paleoenvironmental records indicate that past periods of reduced rainfall were associated with peat oxidation and carbon loss. If warming temperatures or altered rainfall patterns lower water tables, deeper peat layers could become exposed to oxygen, accelerating microbial decomposition and increasing emissions. Under sustained climate stress, this gradual release could evolve into a stronger positive climate feedback.
Storing carbon that has accumulated over the past 10,000 years, the Congo Basin peatlands represent one of the planet’s most significant long-term carbon archives. However, despite their global importance, these remote ecosystems remain among the least studied tropical peatlands on Earth. Large parts of the central Basin are difficult to reach, and travel to isolated lakes and swamp forests often requires boats. As a result, their full role in the global carbon cycle has remained uncertain. Protecting the Basin begins with recognizing how closely its future is tied to the global climate.
Map: Nature Geoscience
Sources: ScienceDaily, Gizmodo, The Guardian, ScienceDirect