Tiny patches of deforestation, often no larger than a football field, are responsible for more than half of all carbon losses in the Tropics, according to a new study that challenges long‑held assumptions about the drivers of emissions in the world’s most important forests.
Published in Nature, the research delivers the most detailed reconstruction to date, showing how tropical forest carbon between the Tropics of Cancer and Capricorn has changed over the past 30 years. Scientists at the Laboratory for Climate and Environmental Sciences (LSCE) in France, working with the European Space Agency’s Climate Change Initiative, found that clearings smaller than two hectares account for 56% of net carbon losses, despite representing just 5% of the total disturbed area.
The team used a high‑resolution bookkeeping approach that combines sub‑hectare satellite observations with new biomass‑recovery curves, enabling carbon losses and gains to be mapped at a 30‑metre scale. Their analysis shows that disturbances in tropical humid forests caused nearly 16 billion tonnes of carbon loss between 1990 and 2020, whilst tropical dry forests showed a rough balance between disturbance‑driven losses and natural regrowth.
According to Yidi Xu and Philippe Ciais, the study’s lead authors, the breakthrough came from the unprecedented detail provided by ESA’s biomass maps. “Unlike previous global models that rely on simplified assumptions or continental averages, our approach captured how disturbance type, size, and local climate conditions shape forest recovery,” they said. “This allowed us to discover that small‑scale human activities, not just large clear‑cutting or wildfires, are quietly driving the majority of tropical carbon losses.”
Most of these clearings are not linked to logging or catastrophic fires.
Instead, they reflect the cumulative impact of everyday human activity, expanding croplands, creating pasture, building roads, and establishing settlements. In humid forests, these disturbances often fail to regrow, locking in long‑term emissions and amplifying the climate impact of each hectare lost.
The study also shows that disturbances are increasingly encroaching on denser, more carbon‑rich humid forests. While undisturbed tropical forests continue to act as a carbon sink, their ability to offset losses elsewhere is now only just enough to keep the overall tropical carbon balance close to neutral.
The findings carry significant implications for climate policy, particularly in regions such as Africa, where small‑scale disturbances dominate. The authors argue that curbing incremental agricultural expansion could deliver far greater climate benefits than previously recognised, and that regenerating forests must be protected from repeated disturbance to maintain their carbon‑storage potential.
ESA’s Head of Actionable Climate Information, Clement Albergel, said the study reinforces the importance of long‑term satellite monitoring. “As tropical forests face increasingly frequent hazards from climate change, fires, and human encroachment, this study underscores a vital truth: even the smallest clearings matter,” he said. “Through ESA’s maps of biomass, we’re gaining an unprecedented view of how these ecosystems lose and regain carbon – knowledge that is crucial for protecting them while there is still time.”
For more information: Xu, Y., Ciais, P., Santoro, M. et al. Small persistent humid forest clearings drive tropical forest biomass losses. Nature 649, 375–380 (2026). https://doi.org/10.1038/s41586-025-09870-7.
