Africa’s Forests Have Switched Sides. The Carbon Math Just Changed.

For decades, the global climate framework has rested on a comforting assumption: that the world’s great tropical forests would continue to absorb carbon, buying time for governments and industries to decarbonise. That assumption has now been definitively challenged.

A study published in Scientific Reports, led by researchers at the National Centre for Earth Observation at the Universities of Leicester, Sheffield and Edinburgh, presents the most detailed analysis to date of biomass changes across Africa’s forests and woody savannas. The study concludes that Africa’s forests are now a net carbon source. Between 2010 and 2017, the continent lost an average of 106 billion kilograms of forest biomass per year, a weighted mean across two sub-periods with different rates of decline, driven overwhelmingly by deforestation in tropical moist broadleaf forests.

Between 2007 and 2010, Africa’s forests and woody savannas were gaining roughly 439 teragrams of aboveground biomass per year. After 2010, the trend reversed. Biomass declined by 132 teragrams per year from 2010 to 2015, and continued falling at 41 teragrams per year through 2017. The worst losses were concentrated in the Democratic Republic of Congo, Madagascar, and parts of West Africa, where deforestation for agriculture, mining, and timber has accelerated sharply.

What This Means for Climate Arithmetic

 

The significance of this finding extends well beyond ecology. Africa’s forests and woody savannas store an estimated 59 petagrams of carbon in aboveground biomass alone. That is roughly equivalent to six years of total global fossil fuel emissions. When forests of this scale stop absorbing carbon and begin releasing it instead, the gap between what nations have pledged under the Paris Agreement and what they need to deliver widens considerably.

The study’s authors note that the current round of revisions to Nationally Determined Contributions will need to be substantially more ambitious to compensate for the loss of this natural sink. Put simply, if forests are no longer doing part of the work, human systems must do more.

This is not an isolated finding. All three of the planet’s major tropical rainforest regions, the Amazon, Southeast Asia, and now Africa, have shown signs of weakening carbon absorption or outright reversal. The Amazon’s eastern reaches have been identified as net emitters. Australian tropical forests have shown similar patterns. Africa’s shift completes a troubling global picture.

 

Implications for Carbon Markets and Forest Finance

 

For participants in voluntary and compliance carbon markets, this study raises pointed questions. Forest-based carbon credits, particularly REDD+ instruments tied to avoided deforestation in Africa, depend on the assumption that standing forests will continue sequestering carbon at historical rates. If the baseline itself has shifted from sink to source, the additionality and permanence claims embedded in many offset instruments deserve fresh scrutiny.

Some forest carbon projects may still deliver meaningful sequestration when they are well governed and rigorously monitored, particularly in regions with intact forest cover. But confidence in tropical forest credits has declined because continental-scale evidence suggests forests are releasing carbon, not absorbing it.

Brazil’s Tropical Forests Forever Facility, launched at COP30, represents one attempt to address this challenge at scale. The facility aims to mobilise $125 billion, combining $25 billion in sovereign sponsor capital with $100 billion in private investment, and to pay forested nations for keeping their forests intact. Governance, land tenure, and economic conditions vary across Africa, so replicating Brazil’s facility may be challenging. The need to develop effective mechanisms has grown.

 

Understanding the Drivers

 

The study identifies deforestation in tropical moist broadleaf forests as the primary driver. This is not random clearing. It is the product of interlocking pressures: agricultural expansion to feed a growing population, infrastructure development, mining for minerals increasingly sought by global supply chains, and rising demand for timber exports, particularly from Asian markets.

Africa’s population is projected to nearly double by 2050. FAO statistics show that annual harvested roundwood on the continent rose from 277 million cubic metres in 1961 to 768 million by 2017. These pressures are structural and cannot be reversed by conservation pledges alone.

Notably, gains in savanna biomass partially offset the losses, likely due to shrub encroachment driven by rising atmospheric CO2, which favours woody plants over grasses. But these gains are far too small to compensate for the sheer volume of carbon being released from destroyed rainforest.

 

Governance, Technology, and the Path Forward

 

The researchers call for stronger forest governance, capacity building in monitoring systems, and financial mechanisms such as REDD+ to create incentives for forest protection. They also highlight the role of satellite-enabled alert systems, such as those deployed in Kenya, which can detect illegal logging in near-real time.

Restoration initiatives like AFR100, the African Forest Landscape Restoration Initiative, aim to bring 100 million hectares of degraded land into restoration by 2030. These programmes matter. But the study makes clear that restoration alone cannot substitute for halting the primary drivers of forest loss. Trees planted today will take decades to store the carbon that mature forests release when they are felled.

A Recalibration, Not a Catastrophe

 

The findings do not mean recovery is impossible. Africa’s forests retain enormous carbon stocks, and the Congo Basin’s core peat-rich forests remain largely intact. Where Indigenous and local communities manage forests directly, outcomes tend to be significantly better. The tools for monitoring, protecting, and restoring forests exist and are improving rapidly.

These findings indicate that climate models, carbon budgets, national pledges, and financial instruments must account for the loss of African forest sinks. Forests will no longer offset as much carbon, so mitigation efforts must increase.

Nature-based solutions remain essential, but they are not self-executing. Forest protection requires sustained capital, credible governance, and honest accounting. The forests of Africa have been absorbing carbon on behalf of the global economy for generations. That benefit is diminishing.

Reference: Rodríguez-Veiga, P. et al. Loss of tropical moist broadleaf forest has turned Africa’s forests from a carbon sink into a source. Scientific Reports 15, 41744 (2025).

https://www.nature.com/articles/s41598-025-27462-3