The Amazon rainforest is losing the rainfall that sustains it, pushing the world’s largest tropical ecosystem closer to a potential tipping point, scientists warn.
A new study, published in Nature Communications, has found that deforestation is driving a sharp fall in rainfall during the Amazon’s dry season and intensifying heat across the region.
The researchers say these changes may be “early signs of biome destabilisation” – in other words, signals that the forest is starting to struggle to keep itself stable.
Researchers analysed satellite and climate records from 1985 to 2020, covering 2.6 million km² (1,000,000 square miles) of Brazil’s Amazon region – nearly four times the size of Texas.
They found that rainfall in the dry season has dropped by about 21mm (0.8 inches), with around three-quarters of that directly linked to deforestation.
Over the same period, maximum daily temperatures rose by about 2°C (3.6 °F), with 16.5 per cent of that increase due to forest loss and the rest caused by global climate change.
Plants are essential to the Amazon's rain cycle. They draw water from the soil and release it through their leaves in a process called transpiration, which helps seed clouds and generate rain.
When trees are cut down, that cycle weakens: fewer clouds form, less rain falls, and the forest becomes hotter and drier – a feedback loop that accelerates decline.
Eventually, the Amazon will reach a tipping point, where the rainforest can no longer support itself. The result is a rapid, irreversible collapse of the ecosystem, which could eventually transform the region into a savannah.
Not only would this massively impact the entire water cycle of South America, but it would also release the carbon currently stored in the rainforest.
“These findings underscore the importance of maintaining and restoring forest cover in the Amazon as a crucial strategy for mitigating climate change and ensuring the stability of ecosystems,” the scientists conclude.
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