The Amazon rainforest is more vulnerable than expected: if deforestation continues, two-thirds of the rainforest could become savannah if the temperature rises by 1.5 to 1.9 degrees, as climate researchers report. This tipping point threatens to occur when deforestation reaches 22 to 28 percent – currently it is 15 to 18 percent. The reason for the increased vulnerability is the rainfall generated by the forest itself: if deforestation increases, the rainforest loses this ability.
The Amazon rainforest is a hotspot of biodiversity and is considered the “green lung” of the earth. The tropical forest trees bind large amounts of the greenhouse gas CO2, and at the same time the water vapor they release cools and humidifies the atmosphere. Rainforests generate a large part of the rainfall they need themselves. In the Amazon region, this self-produced rain locally accounts for up to 50 percent of the total rainfall. The water vapor released by the trees also plays an important role in jump-starting the annual rainy season.
But climate change and deforestation are increasingly affecting the Amazon rainforest: 17 to 18 percent of its area has already been destroyed by deforestation, and dry periods are becoming more frequent due to global warming. There is now increasing evidence that the area is approaching a tipping point. The rainforest could then irreversibly transform into a savannah. However, when this tipping point will be reached is debatable.
Intact forests are resilient
Now a new model analysis provides more precise information. For their simulation, Nico Wunderling from the Goethe University in Frankfurt am Main and his team first reconstructed how much moisture is self-generated in the Amazon region and how it is transported in the atmosphere above the rainforest. They then coupled this with various climate scenarios that simulated warming of 1.5 to more than four degrees. The team then examined how this affects forest cover and the crossing of the tipping point to savanna, with and without additional deforestation.
The simulations showed: Without continued deforestation, the Amazon rainforest will only reach the tipping point when the temperature rises by 3.7 to 4.0 degrees. “But even then there is no point at which the entire Amazon system tips over,” report Wunderling and his colleagues. Even with strong warming, only around 35 percent of the forest area converted into savanna in the model. “This suggests that there are areas in the Amazon rainforest that exhibit high resilience to drought and climate change-related declines in precipitation,” the team said.
If deforestation continues, there is a risk of tipping over at just 1.5 degrees
But that changes drastically if deforestation continues: “After we include deforestation in our analyses, we find tipping points in all climate scenarios,” the researchers write. A warming of 1.5 to 1.9 degrees and a forest loss of 22 to 28 percent are enough to cause large parts of the Amazon region to collapse by the middle of this century. Up to 77 percent of the rainforest could disappear with this already moderate warming.
“(Video: Potsdam Institute for Climate Impact Research)
“Deforestation makes the Amazon significantly more vulnerable than we previously thought,” says Wunderling. His co-author Arie Staal from Utrecht University explains: “If deforestation disrupts moisture transport in one part of the Amazon, entire regions can lose resilience due to spreading drought effects – even hundreds or even thousands of kilometers away. Global warming and deforestation are thereby changing precipitation patterns across the entire Amazon.”
The study provides the most detailed assessment to date of how warming and deforestation affect the stability of the Amazon. But this development is not inevitable, the researchers emphasize: “If deforestation is stopped, already damaged forests are ecologically restored and emissions are reduced quickly, the risks can be significantly reduced,” says co-author Johan Rockström from the Potsdam Institute for Climate Impact Research.
Source: Nico Wunderling (Goethe University Frankfurt am Main) et al., Nature, 2026; doi: 10.1038/s41586-026-10456-0