The data came back in February from a network of 321 monitoring towers distributed across the Amazon basin — towers that have been measuring the flow of carbon dioxide in and out of the forest canopy for up to three decades. What they showed stopped the scientists who read the report. For the first time in the measurement record, more than a quarter of the forest — 26% of the total Amazon biome — was emitting more carbon dioxide than it was absorbing. The world's greatest carbon sink, the ecosystem often called 'the lungs of the Earth,' had turned, in a significant portion of its area, into a lung that was exhaling the planet's future.
The study, published in Nature on March 14 by researchers at Brazil's National Institute for Space Research (INPE), the UK's Met Office, and the University of Leeds, is being described by climate scientists as one of the most consequential pieces of scientific work of the decade. It confirms what the models have been predicting since the 1990s and what direct observations have been suggesting since 2021: the Amazon is not just being deforested at its edges. It is experiencing a systemic internal breakdown driven by the interaction of deforestation, climate change, and drought in ways that amplify each other in a self-reinforcing feedback loop.
The implications cascade outward with terrifying speed. The Amazon stores approximately 150-200 billion tons of carbon. If the entire forest transitions from sink to source — a threshold that this study says is now a plausible scenario within decades rather than centuries — it would release the equivalent of roughly 10-15 years of global fossil fuel emissions. It would also trigger cascading effects on the South American water cycle, devastating agriculture in Brazil, Peru, Bolivia, and beyond. And it would contribute to a climate feedback that would make the 1.5°C Paris Agreement target not just missed but irrelevant.
INPE/Met Office/Leeds study, Nature, March 2026. The affected area — approximately 1.4 million km² — is larger than the combined area of France, Germany, and Spain.
How a Forest Dies From the Inside
The mechanism of Amazon collapse is more complex than the simple image of chainsaws and burning trees that has long dominated public awareness of the crisis. Deforestation — which was dramatically reduced under the Lula government between 2023 and 2025 before partially rebounding — is the catalyst, not the entire cause. What deforestation does is fragment the forest, creating edges where the microclimate breaks down: drier air, more wind, more sunlight reaching the forest floor, more vulnerability to fire.
Once fragmentation reaches a threshold — scientists call it the 'forest edge effect' — the changes begin to spread inward, past the visible deforestation boundary. Drought stress, exacerbated by climate change, kills trees that are internally weakened by edge effects. Fires that would once have been stopped by the humidity of intact forest now spread deeper. The trees that die release the carbon stored in their biomass. The forest canopy thins, allowing more solar radiation, further drying the understory, killing more trees. The cycle accelerates.
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'What we are seeing is not a linear process,' said Dr. Carlos Nobre, lead author of the INPE study and one of the world's foremost Amazon scientists. 'Below the threshold, you can deforest and regrow and the forest is resilient. Once you cross the threshold — and we have crossed it in 26% of the basin — you cannot simply reforest your way back. The climatic and ecological conditions that allow the forest to maintain itself have been altered. You are in a new regime.'
Moisture Recycling Breakdown
The Amazon generates approximately half of its own rainfall through a process called 'biotic pumping' — trees release water vapor that forms clouds and falls as rain, which waters more trees. The INPE study found that in the degraded 26%, this moisture recycling has broken down by 40-60%, creating a drying trend that is self-perpetuating and independent of deforestation rates.
Source: INPE/Met Office/University of Leeds, Nature, March 2026The Political Economy of Destruction
Brazil's agricultural frontier — soybeans, cattle, and the supply chains that depend on them — has pushed relentlessly against the Amazon for decades. Under the Bolsonaro government, INPE itself was politically pressured to underreport deforestation data; its director was fired when he refused. Enforcement agencies were defunded. Land-grabbers moved with impunity. The Lula government reversed these trends significantly, but the institutional damage — weakened enforcement agencies, corrupt local governance, a land registry that still does not accurately reflect legal boundaries — remains.
The international community has provided $2.4 billion to the Amazon Fund since its relaunch in 2023, a significant but inadequate contribution to the scale of the problem. The study's authors estimate that keeping the tipping point from spreading to 50% — a level they consider potentially catastrophic in its own right — would require a combination of zero new deforestation, active restoration of 150,000 km² of degraded forest, and immediate emissions reductions to limit temperature increase to below 1.5°C. All three conditions must be met simultaneously.
An estimated 150-200 billion metric tons of carbon stored in Amazon biomass and soil. Full transition to source status would release the equivalent of 10-15 years of current global fossil fuel emissions.
Fire Season 2025 Sets Record
The 2025 Amazon fire season, driven by the worst drought in the basin's instrumental record, burned approximately 180,000 km² — an area larger than Florida. Smoke reached São Paulo and Buenos Aires. The fires destroyed an estimated 2.3 billion trees and accelerated the transition of affected areas past the tipping threshold, according to post-season INPE analysis.
Source: INPE Deforestation and Fire Monitor, February 2026What Can Still Be Saved
The 26% figure is alarming, but it is not everything. Seventy-four percent of the Amazon remains above the tipping threshold. The science is clear on what is required to keep it there: halting new deforestation immediately, funding restoration at scale, and — critically — addressing the climate change that is making the forest increasingly vulnerable to drought and fire independently of human land use. None of these things are technically impossible. All of them are politically difficult.
What happens in the Amazon over the next decade will be determined not primarily by climate scientists or Brazilian forest rangers, but by financial systems, trade agreements, and the political choices of governments in Brasília, Washington, Beijing, and Brussels. The soybeans on which the pressure depends flow through international supply chains that answer to global commodity markets. The financing for agricultural expansion comes from banks that are subject to regulation. These are points of leverage that have not been used with anything close to the urgency the science demands.
The towers are still measuring. The data will keep arriving. And somewhere in the remaining 74% of the Amazon, trees are still pulling carbon from the air, still generating rain, still performing the ten-thousand-year-old work of making this planet habitable. How long they continue to do so is, in the most literal sense, up to us.