An African forest that spans three countries, supports over 300 million people, and is a habitat for the continent’s most iconic creatures could be storing double the carbon it has previously been credited with, researchers say.
The Miombo is what’s known as a dry forest, a woodland type that has been relatively unstudied compared to the famous rainforests of the Amazon and Congo basin. As large as Mexico, its 1.9 million square kilometres spread west from northern Tanzania to coastal Angola, overlapping with the Mopane woodlands, and south to Mozambique. It provides the people who depend on it with around $9 billion worth of resources, including construction materials, food, and natural medicines, according to a 2016 study.
At the same time, those human activities are changing the Miombo: woodland cover fell by approximately 800,000 km2 in the two decades to 2020. That has attracted the attention of conservationists and commodity traders, with an 11-nation Miombo Alliance, founded in September 2024 and partnered by trading group Trafigura, seeking out forest restoration projects that offer carbon offset opportunities.
But criticism of carbon offsetting schemes has dismissed them as “pollution allowances”, in the words of Rachel Rose Jackson, director of non-profit climate research group Corporate Accountability. And some Miombo locals, such as Edwin Tambara, a director at the African Wildlife Foundation, stress the importance of indigenous ownership and leadership of conservation – a principle that can harness long-held knowledge of best practice when it comes to the forest’s sustainable exploitation.
Now, amid this debate about the future of the Miombo, researchers have found that the forest could be locking up twice the amount of carbon previously thought, amounting to an extra 3.7 billion metric tons sequestered. That’s more carbon than China emitted in 2023.
Allometry, which is the study of how living things change with size, has historically underestimated the carbon characteristics of large trees. But, Professor Mathias Disney of University College London, a co-author of the paper recently published in Communications Earth and Environment journal, explains that a new 3D mapping method using light detection and ranging technology (lidar) can give an “aboveground biomass” estimate with lower uncertainty.
Using this technique, the researchers found that the Miombo stores between 1.5 and 2.2 times more teragrams of carbon than previously thought. If those findings are accurate, the Miombo Alliance is sitting on a more valuable carbon asset than it realised. “If you double the amount of carbon that’s stored across these woodlands … you’ve essentially doubled their dollar value overnight,” Disney told CNN.
That means a greater incentive to protect it and a higher price for cutting it down. But the study points out, the forest’s value lies in more than just carbon. “These ecosystems also hold cultural and spiritual significance, provide habitat for substantial plant and animal biodiversity, and regulate both the climate and water resources.”
Therefore, working with local communities to find ways to reduce the need to encroach upon the forest is essential. One such example, cited by the African Wildlife Foundation’s Tambara, is a 2016 project that brought drought-resistant sugarcane to Tanzanian smallholders, giving them greater yields from smaller plots. That left more of the forest, and its carbon, untouched – which, Corporate Accountability and other environment campaigners say, is the ultimate goal.
