Africa’s forests have shifted from absorbing carbon to emitting it, driven by deforestation and forest degradation.
Between 2010 and 2017, biomass declined sharply, threatening a vital global carbon buffer.
Experts urge urgent policy action to halt deforestation and meet Paris Agreement climate goals.
African forests and woody savanna — traditionally known to have served as carbon sink by removing atmospheric carbon have now transitioned into a carbon source, a groundbreaking study has revealed.
The findings published in the journal Scientific Reports stated that new high-resolution satellite-derived biomass maps indicate the change has been witnessed since 2010 and until 2017.
The study provides the first continent-wide, high-resolution assessment of aboveground woody biomass changes in Africa over a decade. The authors noted that Africa’s ecosystem contribute around 20 per cent of global carbon removals through terrestrial net primary production, 40 per cent of the world’s carbon emissions from biomass burning and 20 per cent of emissions from deforestation and forest degradation.
Carbon is mainly removed from the atmosphere during photosynthesis, the scientists noted, while carbon emissions mainly occur due to forest cover loss during wildfire, agricultural and fuelwood burning and shifting cultivation.
“Between 2007 and 2010, the continent gained 439±66 Tg yr−1 (teragrammes per year) of aboveground biomass, but from 2010 to 2015 biomass declined by −132±20 Tg yr-1 and from 2015 to 2017 this decline continued with a loss of −41±6 Tg yr-1 — indicating they transformed from acting as carbon sink to net carbon source,” the researchers wrote.
The decline in carbon sequestration was primarily driven by significant deforestation in tropical moist broadleaf forests, mainly in the Democratic Republic of Congo, Madagascar and some West African countries, and forest degradation, the findings showed. The continent lost around 106 billion kilogrammes of forest biomass per year, according to the scientists. That is equivalent to the weight of about 106 million cars.
Their findings, they added, are consistent with growing forest loss rates in Africa since 2010 as estimated by the United Nations Food and Agriculture Organization (FAO).
FAO statistics on increasing annual harvested roundwood from 277 million cubic metres in 1961 up to 768 million m3 by 2017 also confirm these forest losses, the authors noted.
“Gains in savanna biomass partially offset these losses, likely due to shrub encroachment. Our findings underline the urgent need for implementing policies to halt global deforestation as required by the Glasgow Leaders Declaration to close the global emissions gap,” they said in a statement.
The long-term persistence of these trends will depend on local governance and whether resources are used sustainably. The results provide further independent evidence of a shift in forest functioning from a carbon sink to a source around this time period, which is consistent with recent studies of all pantropical regions, according to the researchers.
In a statement, Heiko Balzter, senior author and director of the Institute for Environmental Futures at the University of Leicester, said, “This is a critical wake-up call for global climate policy. 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 and avoid catastrophic climate change. Climate finance for the Tropical Forests Forever Facility must be scaled up quickly to put an end to global deforestation for good.”
The researchers warned that the current ongoing revisions of Nationally Determined Contributions to the Paris Agreement need to be more ambitious to compensate for the ongoing loss of natural carbon sinks.
Without urgent action to stop forest loss, the world risks losing one of its most important natural carbon buffers, they concluded.