Vast African Forests Store Twice as Much Carbon as Previously Thought

The carbon-rich miombo woodlands have shrunk considerably in recent decades. (Cynthia R Matonhodze/Bloomberg)

(Bloomberg) -- A forested expanse of southern Africa could store more than double the amount of carbon dioxide as was previously estimated, according to a study published Wednesday, underscoring the value of protecting it.

Africa’s miombo woodlands — named for a type of tree that’s commonly found in them — stretch from Mozambique in the southeast to Angola in the west. Using data from drones, land-based sensors and helicopters, researchers concluded the forests are far more valuable as carbon sinks than prior studies showed. That means they could hold much greater value for carbon offset projects or debt-for-nature swaps. It also means their destruction releases more carbon into the atmosphere than once known. 

The study, led by researchers from the London-based carbon data provider Sylvera Ltd. and funded by the World Bank, was based on about 450 billion laser-scanning measurements across an area in northern Mozambique that’s eight times the size of Manhattan. The team used that data to estimate the weight of the trees and found the amount of carbon they stored above ground was as much as 2.2 times that calculated using older techniques such as measuring trunk diameters.

Extrapolating the results across the miombo woodlands, the researchers concluded that the forests hold almost as much additional carbon as the world’s annual net increase in atmospheric CO2. 

The paper was published in the peer-reviewed journal Communications Earth & Environment. Researchers from University College London and the University of Maryland were among the co-authors.

The main reason why older methods underestimated how much carbon the miombo forests contain is that they were biased toward measuring smaller trees, Andrew Burt, research lead at Sylvera, said in an interview.

The woodlands have shrunk over the past four decades from 2.7 million square kilometers (about 1 million square miles) to roughly 1.9 million square kilometers. They’re home to tens of millions of people, many who lack access to electricity and use the trees as cooking fuel. Deforestation for logging is also a serious problem in the region.

Mozambique ranked among the 10 countries with the biggest annual net loss of forest area between 2010 and 2020, according to the Food and Agriculture Organization of the United Nations. Three other regional countries that host the miombo woodlands were also among the 10 worst.

(Adds ranking on deforestation. An earlier version corrected the description of calculation techniques in the third paragraph.)

©2024 Bloomberg L.P.

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