African forests have shifted from absorbing carbon dioxide to emitting it, complicating global efforts to reach net-zero emissions. This change, driven by deforestation in the Congo rainforest, occurred between 2010 and 2017. Researchers highlight the urgent need for faster reductions in fossil fuel emissions to compensate.
African forests and shrubby woodlands, once a major global carbon sink responsible for 20 percent of all CO2 uptake by plants, have turned into a net source of emissions. The Congo rainforest, known as the "lungs of Africa," previously absorbed an estimated 600 million tonnes of CO2 annually, but logging and mining have reduced this capacity.
A study published in Scientific Reports analyzed satellite data on forest canopy color, moisture, and height, cross-referenced with sparse ground measurements. It found that while biomass increased from 2007 to 2010, African forests lost 106 million tonnes of biomass yearly from 2011 to 2017—equivalent to about 200 million tonnes of CO2 emissions annually. This loss stems primarily from deforestation in the Democratic Republic of Congo (DRC), where impoverished farmers clear land for slash-and-burn agriculture and foreign-owned companies illegally harvest hardwoods like African teak and coralwood.
Heiko Balzter of the University of Leicester, UK, who led the research, warned: "If we are losing the tropical forests as one of the means of mitigating climate change, then we basically have to reduce our emissions of greenhouse gasses from fossil fuel burning even faster to get to near-zero emissions."
However, Simon Lewis of University College London questioned the reliability of satellite data for assessing carbon in high-biomass or selectively logged forests, noting it cannot distinguish tree types like dense mahogany from lighter balsa. He acknowledged: "Deforestation in Democratic Republic of Congo… is higher than it was in the 2000s. And we all know that. But whether that is enough to tip the whole carbon balance of the entire continent is unknown."
The study excluded Congo's peatlands, which store 30 billion tonnes of ancient carbon and absorb a small amount of CO2 yearly. This trend mirrors the Amazon, which also became a net emitter recently, though its deforestation has declined under government measures. At the COP30 summit, Brazil launched the Tropical Forests Forever Facility, offering $4 per hectare for preserved forests, with a $25 billion goal but only $6.6 billion pledged so far. Balzter suggested this could outperform flawed carbon credits: "It’s really important to make this Tropical Forest Forever Facility work, and make it work quite quickly, to try and reverse this trend of the African tree biomass actually releasing carbon into the atmosphere."