Congo Lakes Release Ancient Carbon from Peatlands

Two major lakes in the Democratic Republic of Congo are emitting carbon that has been locked away for thousands of years in surrounding tropical peatlands, raising fresh concerns about climate stability. The findings, published in Nature Geoscience by researchers from ETH Zurich, challenge long-held assumptions that tropical peatlands securely store carbon over millennial timescales.

Scientists examined carbon emissions from Lake Mai-Ndombe and Lake Tumba in the Congo Basin, identifying an unexpected source of atmospheric carbon dioxide.

Ancient Carbon Detected in Lake Emissions

The study found that up to 40% of carbon dioxide released from the two lakes originates from ancient peat deposits, some more than 3,000 years old. This carbon was previously believed to remain stably trapped in waterlogged peat soils.

Researchers described the discovery as surprising, indicating that the carbon reservoir may be “leaking” into the lakes and subsequently into the atmosphere. The exact mechanism by which carbon travels from peatlands into the lakes remains unclear.

Role of Tropical Peatlands

Tropical peatlands are vital carbon sinks. Formed from accumulated dead plant material in waterlogged conditions, peat prevents decomposition and locks away carbon. However, when peat dries due to drought or land-use changes, microbial activity resumes, releasing stored carbon back into the atmosphere.

The swamps and peatlands of the Congo Basin cover only 0.3% of the Earth’s land surface yet store around one-third of the carbon contained in tropical peatlands globally. This makes the region a critical carbon reservoir.

Climate Change and Land-Use Risks

Scientists warn that climate change and deforestation could exacerbate the phenomenon. Conversion of forests into cropland may intensify drought conditions, increasing peat drying and accelerating carbon release.

Important Facts for Exams

• Peat forms from partially decomposed plant material in waterlogged conditions.
• Tropical peatlands are significant global carbon sinks.
• The Congo Basin is the world’s second-largest rainforest after the Amazon.
• Carbon dioxide is a major greenhouse gas contributing to global warming.

Need for Further Research

The Congo Basin remains one of the least-studied major forest ecosystems in the world. Researchers emphasise that more extensive monitoring is essential to understand how climate shifts and human activities may destabilise its vast carbon stores, with potential implications for global climate regulation.