- Deforestation of 22-28% of the Amazon Rainforest, coupled with 1.5-1.9°C of global warming, could trigger a widespread shift of the Amazon Rainforest to degraded forest and savanna grassland ecosystems, a new study warns.
- This looming Amazon threshold modeled by researchers could be reached as early as the 2040s. Hitting this rainforest loss/global temperature threshold, or tipping point, could ultimately impact more than 70% of the Amazon Basin within decades, resulting in release of large amounts of carbon stored in forest and soils.
- Roughly 17-18% of the Amazon has already been deforested, and global temperatures are expected to rise to 1.5°C above preindustrial levels annually as early as 2030.
- Experts underline that the new findings reinforce the urgent need to halt Amazon deforestation, restore significant amounts of rainforest and drastically slash carbon emissions.
Deforestation coupled with climate change is rapidly pushing the Amazon Rainforest toward a perilous tipping point that could come much sooner than previously thought. That’s the warning from a new paper, published in Nature, which determined that deforestation of 22-28% of the rainforest, combined with 1.5-1.9° Celsius (2.7-3.4° Fahrenheit) of global warming, could trigger a widespread transformation of the biome as early as the 2040s.
Researchers found that crossing this deforestation/global temperature threshold could lead to more than two-thirds of the rainforest becoming degraded or transitioning to a savanna ecosystem. Currently, about 17-18% of the Amazon is deforested and 1.5°C of warming over preindustrial levels is likely to be officially reached by 2030, while scientists say it is increasingly likely 2°C (3.6°F) of warming may be surpassed by 2050.
In the worst-case scenario, “This critical [Amazon] threshold could be reached as early as the 2040s,” Nico Wunderling, first author on the paper and a researcher at the Potsdam Institute for Climate Impact Research, told Mongabay in an interview. “Although I’d be a little bit more optimistic: If current [downward] trends [for] Brazilian deforestation continue, then deforestation-wise, we might not reach [the tipping point] by mid-century.”
“I think we can confidently say that the more deforestation happens, the lower this global warming threshold becomes,” said Arie Staal, study co-author and an assistant professor at Utrecht University.
For Carlos Nobre, a professor at the University of São Paulo and co-chair of the
Science Panel for the Amazon, who wasn’t involved in the study, this new research serves as an urgent warning that the Amazon’s tipping point could be reached far sooner than formerly anticipated. Previous research published in 2016 and led by Nobre pointed to around 20-25% deforestation and 2°C warming as a critical Amazon threshold.
“The paper is an improvement of the study we published 10 years ago along the same lines, [and] it shows we are even closer to a tipping point,” Nobre said in an interview with Mongabay. “I think this paper is very important to show how urgently we have to save the Amazon.”
A ‘tremendous risk’
The authors of the new paper analyzed climate projections, hydrological modeling and atmospheric moisture transport to arrive at their findings.
Up to half of the Amazon Rainforest’s precipitation is recycled by its trees, but large-scale deforestation disrupts this vital biome-wide hydrological cycle. Major tree loss reduces the release of water vapor to the atmosphere, decreases rainfall and intensifies drought. And when moisture transport is disrupted in one area, the resulting drought stress can kill trees hundreds of kilometers away, Staal explained.
Where Amazon deforestation occurs could be crucial. According to the team’s simulations, projected forest loss will happen predominantly in the eastern Amazon Basin contributing to “downwind cascading transitions,” with much dryer air moving westward over the more forested part of the biome, weakening the hydrological cycle.
However, “If we’re beyond a tipping point, that doesn’t mean that that the Amazon Rainforest is gone the next day,” Wunderling explained, as that process would unfold over decades. “But it means that we’re then on a hard-to-reverse trajectory.”
Hitting the threshold would mean less rainfall, triggering a transition of healthy rainforest into dry forest, savanna or treeless ecosystems, though the detailed impact remains unclear. “But what is clear,” Wunderling said, is that the Amazon would become “a type of degraded ecosystem that cannot fulfill its ecosystem services, such as water recycling, such as the biodiversity … we currently see.”
This scenario is already playing out in the heavily deforested southern Amazon, Nobre noted, a region already very close to its own tipping point. There, the dry season has already been extended by 4-5 weeks annually and rainfall has seriously declined.
Consequences of hitting this threshold across the wider Amazon would be far-reaching, including the loss of the rainforest’s unique biodiversity, disruption of regional water cycles, and in time, the release of billions of tons of CO2 currently locked up in Amazonia’s forest and soils.
“This is a tremendous risk for the Amazon,” Nobre emphasized. But in turn, these impacts would eventually extend far beyond the rainforest, with other ecosystems, such as tropical savanna that depend upon the rainforest for moisture, becoming deeply degraded and transitioning from grassland to semiarid vegetation.
Halting deforestation, ramping up reforestation
The current study offered an additional finding: In the absence of additional Amazon deforestation, a large-scale transition would not become likely until warming levels of around 3.7-4°C (6.7-7.2°F). This would still be a “highly unsafe scenario” for the rainforest, the authors write, as up to 35% of the Amazon would still degrade or become savanna.
But for Wunderling, this finding shows that the existing rainforest system has resilience in the face of warming temperatures — provided that deforestation is tempered. That’s a finding which offers hope that the Amazon crisis “can be turned around,” he said. “In that way, it is a positive scenario, as it shows we need to reach a very high level of warming [of 3.7–4°C] before we see these partial system-wide Amazon Rainforest transition risks.”
The study authors emphasize the urgent need for action to bolster rainforest resilience in the face of climate change by protecting existing forest and restoring lost forest areas. They point to efforts such as Brazil’s pledged restoration of 24 million hectares (59.3 million acres) of rainforest as positive steps.
Wunderling noted that new research could be done to determine exactly where reforestation would do the most good, “so that this atmospheric moisture recycling feedback is revitalized.”
“The negative effects of deforestation can largely be compensated … by reforestation,” Staal added, which “also would give [the world] time” to decarbonize.
Nobre agreed to the urgent call for action: “We really have to move very quickly to stop complete deforestation and degradation [and] do larger forest restoration [while] avoiding global warming reaching 1.8°C [3.2°F],” he said.
“If we don’t do that by 2040, we cross the tipping point; then it is impossible to save the Amazon.”
Banner image: Burned-over forest in the Brazilian state of Acre, one of the epicenters of deforestation in the Amazon. Image by Victor Moriyama/Climate Visuals (CC BY-NC-ND 4.0).
Study finds deforestation accounts for major Amazon rainfall decline
Citation:
Wunderling, N., Sakschewski, B., Rockström, J., Flores, B. M., Hirota, M., Staal, A. (2026): Deforestation-induced drying lowers Amazon climate threshold. Nature. doi:10.1038/s41586-026-10456-0
Hansen, J. E., Sato, M., Simons, L., Nazarenko, L. S., Sangha, I., Kharecha, P., … Li, J. (2023). Global warming in the pipeline. Oxford Open Climate Change. doi:10.1093/oxfclm/kgad008
Nobre, C. A., Sampaio, G., Borma, L. S., Castilla-Rubio, J. C., Silva, J. S., & Cardoso, M. (2016). Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm. Proceedings of the National Academy of Sciences, 113(39), 10759-10768. doi:10.1073/pnas.1605516113
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