In about three-quarters of the Amazon, forest resilience to disturbance has declined since the early 2000s, which scientists consider a red flag.
A new study, which analyzes data on Amazonian vegetation taken by satellite, has found that the resilience of the Amazon rainforest – the ability to recover from events such as droughts or fires – has consistently declined by more than three-quarters of the ecosystem since the early 2000s.
The research, led by Chris Boulton and Tim Lenton from the University of Exeter, UK, and Niklas Boers from the Technical University of Munich and the Institute for Climate Impact Research in Potsdam, Germany , illustrates the need to minimize human land use in the Amazon region and limit greenhouse gas emissions on a global scale. The results are published in the journal Natural climate change
According to the authors, the Amazon could soon reach a tipping point, the crossing of which would trigger vegetation dieback and turn much of the forest into savannah. This would have major implications for biodiversity, global carbon storage and climate change.
It’s unclear when this tipping point might be reached, but the study says the loss of resilience is “consistent” with approaching a tipping point. “Many researchers have speculated that a tipping point may be reached, but our study provides vital empirical evidence that we are approaching that threshold,” Boers says.
“If exceeded, the consequences would be devastating on several levels. The world, South America and Brazil would lose an important ecosystem that provides many of their services, such as climate and water regulation, biodiversity, cultural context and food supply, for nothing name a few.“Warns Alex Koberle, researcher at the Grantham Institute for Climate Change and the Environment at Imperial College London (UK) in statements to the Science Media Center (SMC) in the UK.
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pronounced loss
Scientists analyzed 30 years of satellite data, revealing a decline in resilience since the early 2000s, with more pronounced losses in drier areas, as well as regions within 200 kilometers of large farms and settlements. .
“This is alarming, since the models of the Intergovernmental Panel on Climate Change (IPCC) predict a general drying of the Amazon region in response to anthropogenic global warming.Boer Notes.
The study used a variety of data sources, including vegetation optical depth (VOD), a measure of the total biomass of trees and other plants in a given area.
Despite climate change, average rainfall in the Amazon has not changed dramatically in recent decades. However, dry seasons have lengthened and droughts have become more frequent and severe.
VOD measurements from the study suggest that overall biomass has decreased slightly, but the loss of resilience is much more pronounced. The researchers insist on this distinction between resilience and the average “state” of the tropical forest.
“The jungle can have more or lessIt looks the same, but it can lose resilience, slowing recovery after a major event like a drought,” says Lenton, director of the Global Systems Institute in Exeter, UK.
“Previous studies based on computer simulations have indicated that large parts of the Amazon may be heading for dieback before showing a strong change in average state. Our observational analysis now shows that in many regions, destabilization already appears to be underwayBoulton warns.
time to act
“Our new analysis of empirical data provides further evidence for concerns about forest resilience, especially in the near future.Lenton says. “Confirms that it is necessary to strongly limit logging, but also to limit global greenhouse gas emissions, to safeguard the Amazon”.
“Passing such a tipping point would make it even more difficult to meet our overall net emissions goal, due to the loss of the “free service” provided by Amazon’s carbon sink, which currently eliminates some of our emissions. »says Chantelle Burton, scientist at the Hadley Center of the Meteorological Office (UK) in statements to the SMC.
However, it seems that there is still time to act: “Our study shows that the Amazon is approaching a tipping point, but also that it may not have passed it yetBoers concludes.
Reference:
“Pronounced loss of resilience of the Amazon rainforest since the early 2000s”. Natural climate change. 2022