The data shows that the Amazon is approaching a tipping point after which rainforests will be lost, with “profound” consequences for global climate and biodiversity.
Computer models have previously pointed to the possibility of an Amazon mass die-off, but the new analysis is based on actual satellite observations over the past three decades.
A new statistical analysis shows that more than 75% of intact forests have lost stability since the early 2000s, meaning it takes longer to recover from droughts and wildfires.
The greatest loss of stability is seen in areas closer to farms, roads, and urban areas, as well as in regions that are becoming drier, suggesting that deforestation and global warming are the cause. The scientists conclude that these factors “may already bring the Amazon closer to the critical threshold of rainforest extinction.”
The study does not predict when the tipping point might be reached. But the researchers warned that by the time a tipping point can be detected, it will be too late to stop it.
Once launched, the rainforest will turn into grassland in at most a few decades, releasing huge amounts of carbon and further accelerating global warming.
Tipping points on a planetary scale are among the biggest fears of climate scientists because they are irreversible on a human time scale. In 2021, the same statistical method revealed warning signs of the collapse of the Gulf Stream and other key Atlantic currents, with “an almost complete loss of stability over the past century.”
The cessation of these currents would have catastrophic consequences for the whole world, interrupting the monsoon rains and endangering the Antarctic ice sheets.
Another recent study found that a significant portion of the Greenland ice sheet is on the verge of a tipping point that will lead to a sea level rise of 7 meters over time.
“Many researchers suggest that a tipping point for Amazon may be reached, but our study provides important empirical evidence that we are approaching this threshold,” said Professor Niklas Burs from the Technical University of Munich in Germany.
“Seeing this kind of buckling in observations is worrisome. The Amazon rainforest stores a huge amount of carbon that can be released even in the event of a partial die off.
The edge of the ice sheet in the north of Kangerlussuaq, Greenland. Photo: Hannibal Hanschke/ReutersScientists said the Amazon’s extinction had “profound consequences on a global scale”. Burs added: “The Amazon is definitely one of the fastest elements of the climate system.”
A study published in the journal Nature Climate Change examined satellite data on the amount of vegetation in more than 6,000 grid cells in the pristine Amazon from 1991 to 2016.
They found that over the past 20 years, areas affected by drought or fires have taken significantly longer to recover than before. This is a key sign of increasing instability, as it shows that recovery processes are fading.
The drier parts of the forest lost more stability than the wetter ones. “This is worrisome because the IPCC [Intergovernmental Panel on Climate Change] Models predict a general drying up of the Amazon region in response to global warming,” Burs said.
Areas close to human destruction of the forest have also become more unstable. Trees are critical to rain production, so cutting them down to clear land for beef and soybeans creates a vicious cycle of drier conditions and more tree loss.
Another 2021 study based on data from hundreds of small plane flights found that the Amazon is now emitting more carbon dioxide than it absorbs, mostly due to fires.
But Burs said the data indicated the tipping point had not yet passed: “So there is hope.” Professor Tim Lenton of the University of Exeter in the UK, co-author of the study, said: “This supports efforts to reverse deforestation and degradation of the Amazon to restore some resilience to ongoing climate change.”
Chris Jones of the Met Office’s Hadley Centre, who is not part of the research team, said: “This study adds to the strong evidence that climate change is a risk today and that these serious and irreversible impacts could become a reality. We have a narrow window of opportunity to take urgent action.
“An alarming conclusion [of the study] is consistent with other recent studies of increased tree mortality, increased fires, and reduced regional carbon sinks. An IPCC report released last week said the risks of large-scale single events, such as the Amazon die-off, are now closer than ever.”
Bernardo Flores of the Federal University of Santa Catarina in Brazil said: “The study shows that while a forest may appear beautiful, with its normal structure and biodiversity, the internal processes are already subtly changing, reducing the system’s ability to persist over a long run. The approach taken is interesting in that it provides early warning signals of these changes.”
Flores’ research showed that savannas expanded into the heart of the Amazon due to forest fires.
The government of Brazilian President Jair Bolsonaro has come under fire for encouraging further deforestation, which rose 22% in the year to November, the highest level since 2006.
Burs said: “It is very difficult to say which will come first: [loss of stability] natural vegetation systems or just bulldozers approaching the forest.”