The Congo Basin still absorbs carbon - but how much, and for how long, is contested
The Congo Basin is the largest remaining net carbon sink in the tropics, yet published figures for how much carbon it takes up differ widely because they measure different things. At the same time, about 780,000 hectares of its primary forest were lost in 2024, and peer-reviewed work shows the wider tropical sink has been weakening since the 1990s.
Key points
- WRI: the basin is the tropics' largest remaining net carbon sink.
- Primary forest loss in 2024: 780,000 hectares, 0.44 percent of the basin's primary forest.
- Loss rose 14.2 percent in 2024 compared with 2023.
- DRC accounts for over 75 percent of the basin's primary forest loss.
What happened
The Congo Basin covers six countries - Cameroon, the Central African Republic, DR Congo, Equatorial Guinea, Gabon and the Republic of Congo - and supports roughly 100 million people. Its forests store carbon in trees and in the Cuvette Centrale peatlands, which CIFOR-ICRAF puts at about 29 billion tonnes of carbon over 167,600 square kilometres.
Most arguments about the basin are arguments about definitions. Gross absorption counts what trees take in; a net sink subtracts what is released by tree death, fire and clearing. Primary forest loss, tree cover loss and permanent deforestation are also three different measures, and swapping them produces very different headlines.
Claim by claim
Why this label: World Resources Institute, citing Global Forest Watch data. This is a net figure - what remains after emissions from the same forests are subtracted.
On the ladder: a claim earns Verified from primary evidence, or from two independent sources that do not copy each other.
Why this label: CIFOR-ICRAF reporting gives this much larger number. It does not match WRI's net figure because the two are not measuring the same thing, and neither source presents its number as the other's measure. Readers should not treat 160 million and 600 million as two estimates of one quantity.
On the ladder: credible sources conflict, so we show both workings. One side's own statement is that side's position — never proof.
Why this label: WRI / Global Forest Watch figures. Primary forest loss is not all permanent deforestation: WRI notes loss from shifting agriculture, charcoal and fire can be temporary, though recovery can take decades.
On the ladder: a claim earns Verified from primary evidence, or from two independent sources that do not copy each other.
Why this label: From the peer-reviewed study in Nature by Hubau and colleagues, tracking some 300,000 trees over 30 years, as summarised by the University of Leeds. The same work found the African sink stayed stable for three decades to 2015 while the Amazon's declined, with signs of increased African carbon losses after 2010.
On the ladder: a claim earns Verified from primary evidence, or from two independent sources that do not copy each other.
Why this label: Not established. WRI still measures a net sink for 2015 to 2024, while CIFOR-ICRAF reports a December 2025 University of Leicester study finding biomass losses of 106 million tonnes a year between 2011 and 2017, raising the possibility that parts of the basin are turning from sink to source. A possibility in some areas is not a basin-wide finding.
On the ladder: credible sources conflict, so we show both workings. One side's own statement is that side's position — never proof.
What we know / what we don't know yet
What we know
- The basin is still a net sink on WRI's 2015 to 2024 measure.
- Primary forest loss rose in 2024, and DR Congo accounts for most of it.
- The long-running peer-reviewed record shows tropical forest uptake weakening since the 1990s.
What we don't know yet
- A single basin-wide net figure that all research groups agree on, using the same definitions and years.
- Whether the post-2010 signs of rising carbon losses in African plots have continued since the plot data used in these studies.
Why it matters
If the last big tropical net sink weakens, the world loses part of the free help it gets against climate change, and every emissions target gets harder. The size of that risk depends on numbers that are still argued over, which is a reason to fund measurement in the basin, not to pick the scariest figure.
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