Africa’s forests flip from climate shield to carbon source

For decades, the world counted on Africa’s vast tropical forests to quietly absorb excess carbon dioxide. But new research in Scientific Reports reveals that this natural climate buffer has collapsed: Africa’s forests are now releasing more carbon than they capture.

A decade of satellite data and machine-learning analysis led by the University of Leicester’s National Centre for Earth Observation shows a dramatic shift, as highlighted by Zme Science.

While in 2007–2010 African forests gained roughly 439 million metric tons of biomass each year, the trend reversed in 2010–2017, with forests losing about 106 million tons of biomass annually, equivalent to roughly 200 million tons of CO₂ released.

“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 losses are concentrated in tropical moist broadleaf forests—in the Democratic Republic of Congo, Madagascar, and West Africa—and are driven by accelerating human pressures including deforestation, slash-and-burn agriculture, logging, and expanding roads and mines.

To quantify the change, researchers combined NASA’s GEDI laser scanner data from the ISS with Japan’s ALOS radar imagery to produce the most detailed biomass maps ever made for the continent, at 100-meter resolution. Ground checks confirmed the findings.

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

Savannas did gain some carbon due to shrub expansion, but not nearly enough to counter losses in humid tropical forests.

“Deforestation in Democratic Republic of Congo… is higher than it was in the 2000s,” said Simon Lewis of University College London, speaking to New Scientist. “But whether that is enough to tip the whole carbon balance of the entire continent is unknown.”

The finding now places all three major tropical forest regions, the Amazon, Congo Basin, and Southeast Asia, in the same alarming category: no longer reliable carbon sinks.

“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.”

Africa’s forests still hold about 59 billion tons of carbon above ground, equivalent to six years of global fossil-fuel emissions. Losing more of that, the authors warn, could further destabilise the global climate.

Initiatives like AFR100 and platforms like Restor aim to restore damaged landscapes, but without large-scale international financing, they cannot keep pace with the accelerating loss.

In just a decade, one of the planet’s most important climate defences has flipped. Whether it can be rebuilt depends on global decisions made now.

By Sabina Mammadli