The study, led by a team of scientists from the University of Bristol, used satellite data to examine the world’s three largest tropical forests — the Amazon, Central Africa, and Borneo — and revealed that the destruction of these ecosystems is currently happening at a faster rate than regrowth.

This is the first of its kind to estimate aboveground carbon absorption in tropical forests recovering from degradation and deforestation. The researchers found that areas recovering from human disturbances, such as logging, as well as forests re-growing in previously deforested areas, were annually removing at least 107 million tonnes from the atmosphere. However, the total amount of carbon being taken up in aboveground forest re-growth was only enough to counterbalance 26% of the current carbon emissions from tropical deforestation and degradation.

Lead author Dr Viola Heinrich, who gained her PhD in physical geography at Bristol University, noted that while the protection of ancient tropical forests remains a priority, the study demonstrated the value in sustainably managing forest areas that can recover from human disturbances. “The carbon recovery models we developed can inform scientists and policymakers on the carbon storage potential of secondary and degraded forests if they are protected and allowed to recover,” she said.

The research team included experts from Brazil’s National Institute for Space Research. Dr Jo House, co-author of the study, emphasised the urgency of reducing deforestation and restoring areas, which are the most cost-effective and immediate way to remove carbon from the atmosphere. “Our research demonstrates that time is running out,” she said.

The study also found that one-third of forests degraded by logging or fire were later completely deforested, highlighting the vulnerability of the carbon sink in recovering forests. Dr Heinrich noted that tropical forests, which provide vital resources for millions of people and animals, need to be protected and restored for their carbon and climate value. She added that on a local scale, people need to be allowed to continue to use them sustainably.

The findings of this study align with previous research that has shown that the world’s forests are under threat due to human activities. The Global Forest Resources Assessment 2020, released by the United Nations Food and Agriculture Organization, revealed that the world lost 178 million hectares of forest between 1990 and 2020. Deforestation, forest degradation, and wildfires were among the major drivers of this loss.

The researchers hope that their findings will inform decisions about protecting tropical forests and reducing carbon emissions. “The urgency and scale of the problem means that we must now consider secondary forests as part of the solution to the climate crisis,” said Dr Heinrich.