African forests have officially flipped. Instead of absorbing carbon, they’re now releasing it

For decades, we’ve relied on the world’s tropical forests to do the heavy lifting in the fight against climate change. We assumed that the vast greenery of Africa was soaking up our excess carbon dioxide. But a new study in Scientific Reports suggests that safety net has snapped.

A new study in Scientific Reports finds that in recent years, the continent’s forests changed from a carbon sink to a carbon source, releasing more CO2 than it absorbs.

A Continent-Wide Reversal

Using over a decade of satellite imagery and machine learning, researchers led by the University of Leicester’s National Centre for Earth Observation tracked the “breathing” of the continent. The data reveals a stark pivot:

• 2010–2017: The trend reversed. The continent began losing an average of 106 million tons of biomass each year.
• 2007–2010: African forests were growing, gaining roughly 439 million metric tons of biomass annually.

To put that in perspective, that annual loss releases roughly 200 million tons of carbon dioxide back into the atmosphere.

“This is a critical wake-up call for global climate policy,” said Professor Heiko Balzter, senior author of the study and director of Leicester’s Institute for Environmental Futures, in a university statement. “If Africa’s forests are no longer absorbing carbon, it means other regions and the world as a whole will need to cut greenhouse gas emissions even more deeply to stay within the 2°C goal of the Paris Agreement.”

The “bleed” is concentrated in tropical moist broadleaf forests, specifically in the Democratic Republic of Congo (DRC), Madagascar, and West Africa. These humid ecosystems, once reliable reservoirs for carbon, are being dismantled.

Satellite Imagery

How do we know this with such precision? For a long time, we didn’t. Field data in remote African forests is notoriously sparse. To get a clear picture, Balzter and his colleagues turned to an arsenal of Earth-observing satellites, including NASA’s GEDI laser instrument aboard the International Space Station and Japan’s ALOS radar satellites.

By combining laser scans (which measure how tall the trees are) with radar (which tracks density), the team created the most detailed biomass maps of Africa ever produced, down to a 100-meter resolution. When they cross-checked this with ground measurements, the results were unambiguous.

“We can claim with high confidence that the transition from a carbon sink to a source is real,” the authors wrote.

On average, Africa’s tropical forests gained carbon until 2010, then lost it rapidly—especially between 2015 and 2017. Gains in savannas, likely caused by shrub encroachment from rising CO₂ fertilization, offered only partial relief. They were not enough to offset the destruction elsewhere.

Anthropocene Effect

The main cause for this reversal is exactly what you’d expect: humans. Across the Congo Basin, the world’s forgotten rainforest, deforestation has surged. Farmers clear land for subsistence crops using slash-and-burn methods. Timber companies, often foreign-owned, strip out valuable hardwoods. Roads and mining sites carve open once-intact forests.

“Deforestation in Democratic Republic of Congo… is higher than it was in the 2000s,” said Simon Lewis, a forest ecologist at University College London, who was not involved in the study, speaking to New Scientist. “But whether that is enough to tip the whole carbon balance of the entire continent is unknown.”

However, the authors believe it is. The shift they detected aligns with independent evidence like rising timber harvests and satellite-observed forest loss rates, which was reported by the FAO and NASA since 2012.

The collapse follows a worrying pattern. In the Amazon, decades of deforestation and heat have turned parts of the rainforest into net emitters. In Southeast Asia, peatland fires have done the same. For the first time, all three of the planet’s major tropical forest belts—Amazonia, the Congo Basin, and Southeast Asia—are no longer reliable carbon sinks.

The implications reach far beyond Africa. “If we are losing the tropical forests as one of the means of mitigating climate change,” Balzter also told New Scientist, “then we basically have to reduce our emissions from fossil fuel burning even faster to get to near-zero emissions.”

The Stakes Are High

The study’s authors estimate that Africa’s forests and woodlands still hold about 59 billion tons of carbon above ground, a staggering figure, roughly equivalent to six years of global fossil fuel emissions. Losing even a fraction of that could destabilize the global carbon cycle and send us even further down the climate spiral.

The research also proves how fragile natural climate buffers have become. As forests flip from sink to source, they magnify rather than mitigate warming. Efforts such as the African Forest Landscape Restoration Initiative (AFR100) and digital platforms like Restor are beginning to mobilize local communities, investors, and governments toward reforestation goals. But without decisive global financing, those projects will struggle to match the scale of loss.

On satellite maps, the Congo Basin still appears as a vast stretch of vegetation spanning six nations and more than 3 million square kilometers. But hidden beneath that canopy are clearings for farms, scars from logging, networks of roads cutting through what once seemed endless wilderness.

In the span of a decade, Africa’s forests have crossed a critical threshold. What was once a shield against climate change is now feeding it. “The world otherwise risks losing an important carbon sink needed to achieve the goals of the Paris Agreement,” the researchers warned.

Whether that shield can be restored depends on choices made now—by governments, financiers, and consumers far beyond Africa’s borders.