Exclusive: 25 years of data reveal the new driver of forest carbon loss

The conversation around tropical forest loss has long centered on deforestation: the visible, mappable clearing of trees for agriculture, logging, and development. It's a tractable problem. You can see it from space and draw lines around it.

But biomass tells a different story. Across the pantropics, the dominant driver of biomass loss isn't deforestation. It's degradation: the slow thinning of forests that remain standing, not resulting in any land cover/land use change. And for the people whose livelihoods, investments, and climate commitments depend on those forests staying intact, it's a problem that has been hiding in plain sight.

What data shows

The headline finding is consistent across every region analyzed: degradation dominates, not as a secondary factor, but overwhelmingly. The more striking insight is where the losses are happening. Not at the deforestation frontier, but also in the intact interior. Not where forests are disappearing, but where they're quietly thinning and where their health decreasing.

In the Brazilian Amazon, the most alarming signal isn't Rondônia, the textbook deforestation frontier. It's Amazonas, the vast, supposedly secure interior, where less than 1 percent of forest area has been lost. Biomass there is declining almost entirely from degradation, and the rate is accelerating: annual losses have worsened by 92 million tonnes per year since 2015. Even in Rondônia, where 19.3 percent of forest area has been cleared, degradation still accounts for nearly four times more biomass loss than clearing. The frontier we've been watching isn't where the carbon is being lost.


In Papua, forest area actually grew slightly over the past 25 years while biomass declined, a pattern consistent with selective logging or fire-related thinning rather than land conversion. The forest looks intact but the carbon is receding.

In the Democratic Republic of Congo (DRC), 25 of 26 provinces are losing biomass, driven by diffuse smallholder disturbance and shifting agriculture across an enormous landscape. The losses aren't concentrated in any one place, they're everywhere, and they're worsening.


In the United States, the net picture is one of biomass gain. But the losses that do exist are almost entirely fire-driven degradation. California lost only 1 percent of its forest area but 13 percent of its forest stock. Fire doesn't convert land. It reduces density, quietly, across millions of acres. Communities that live alongside these forests feel the consequences. The carbon accounting, until now, largely has not.

The through-line across all four regions: the places we think of as secure are not. Our trend lines closely mirror independent data sources: this is not a data artifact or a methodological quirk. It is what is happening to these forests.

Why it matters for forest carbon finance

The reason avoided degradation has been chronically underfunded isn't that the ecological or climate value is in doubt. It's that the measurement infrastructure to credibly quantify it hasn't existed. And without credible measurement, there is no basis to reward protection, for carbon credits, no signal to attract investment.

Standard forest monitoring looks at where forests disappear. Biomass-based monitoring looks at what forests contain. A forest that loses 20 percent of its carbon while retaining 99 percent of its area is invisible to deforestation alerts, but fully visible in above-ground biomass data. That distinction is the difference between a forest that generates finance and one that doesn't, regardless of what's actually happening to its carbon.

That constraint is now lifting. 

Today we're launching the Chloris Biomass Viewer, a public tool that makes 25 years of pantropical above-ground biomass data explorable across 1,455 jurisdictions. For the first time, anyone working in forest carbon, from developers, investors, standards bodies, and governments, can see not just where forests are disappearing, but where they are thinning, and how fast. Often an indicator where deforestation will happen in the future. Jurisdictions that have been protecting forests and absorbing degradation pressure with no financial return now have the evidentiary foundation to make that case.

The 19 Gt net loss across pantropical forests since 2000 is not primarily a story of land conversion. It is a story of forests quietly thinning under pressure from climate and human disturbance, in ways that only direct biomass estimates can reliably detect. Bringing that loss into view is the first step toward rewarding the communities and governments working to prevent it.

What the science has established

The scientific literature on this has been building for years. Baccini et al. (2017) found that degradation accounts for roughly 69 percent of tropical carbon losses. Qin et al. (2021) put that figure at 73 percent for the Brazilian Amazon alone. Matricardi et al. (2020) found that the total degraded area in Brazil exceeded the deforested area over a 23-year period. Pearson et al. (2017) estimated 2.1 Gt CO₂ per year from degradation across 74 countries, a number larger than many national emissions inventories.

The mechanisms are well understood: selective logging, fire, drought stress, and climate-induced dieback all reduce biomass density across vast areas of standing forest. Bourgoin et al. (2024) found that selective logging reduces forest height by 15 percent and fire by 50 percent, with low recovery after 20 years. Gatti et al. (2021) showed that eastern Amazonia has already flipped from carbon sink to carbon source.

This isn't a peripheral finding. It is the central story of tropical forest carbon, and for the first time, the tools to see it, measure it, and act on it at scale are publicly available.


Analysis based on Chloris Geospatial's pantropical AGB dataset covering 1,455 jurisdictions, 2000–2025. Full references available on request.

The Chloris Biomass Viewer is publicly available. Browse 25 years of global, above-ground biomass trends across, from the Amazon interior to the Congo Basin to the forests of Southeast Asia. Explore the Chloris Biomass Viewer