Amazon rainforest nears Savannah’s ‘tipping point’


Jhe trees in the Amazon rainforest could soon die en masse, researchers warn. According to a 20-year satellite study published yesterday (March 7) in Natural climate change, the famous forest is showing signs of poor health that could mean that large parts of it will become savannah in the near future. Such ecological change could happen quickly, says Timothy M. Lenton, co-author of the study and director of the Global Systems Institute at the University of Exeter. CNN. “My hunch, for what it’s worth, (is that) this could happen within the span of decades.”

“The Amazon is a custodian of biodiversity and has a vital ability to extract carbon dioxide from the atmosphere, so it is clearly concerning that its health is deteriorating as human-caused deforestation and climate change have increasingly powerful and harmful impacts on the ecosystem,” University of Reading climatologist Richard Allan, who was not involved in the study, said in a statement to the Science Media Center (SMC). .

Covering more than 6 million square kilometers and spanning parts of eight countries, the Amazon Basin is home to the largest forest in the world, larger than the two largest forests combined. About a fifth of the forest has already disappeared since the pre-industrial era, explain the authors of the study. BBC News, and the rest are threatened by deforestation and climate change. To measure the resilience of the massive forest, the researchers analyzed satellite data to determine forest biomass and greenness from 1991 to 2006, looking for month-to-month changes in response to weather conditions. More than three-quarters of the forest had shown reduced resilience since 2000, with trees taking longer to recover from stresses such as droughts and fires. The most pronounced loss of resilience occurred in areas with less rainfall and those geographically closer to human activity, the researchers report.

“As a scientist, I’m not supposed to have anxiety. But after reading this article, I’m very, very anxious,” said Carlos Nobre, a climatologist at the University’s Institute for Advanced Study. of São Paulo in Brazil, which did not take part in the work. The Washington Post. “This document shows that we are going in the wrong direction. . . . If we pass the tipping point, that’s very bad news.

The paper’s conclusion is similar to previous modeling studies, but experts say the new study is stronger because it’s based on real-world data. “There has been a lot of research into this area of ​​potential Amazon dieback over the past two decades, with great uncertainty in model projections,” said Chantelle Burton, a climatologist at the Met Office Hadley Center who doesn’t did not participate in the research. the SMC. “What this study does is offer observational evidence of what is already happening in this important carbon sink, and shows that human land use and changes in weather and climate are already driving a significant change in the system.”

“Passing such a tipping point would make it even more difficult to achieve our goal of net zero emissions globally due to the loss of the ‘free service’ provided by Amazon’s carbon sink which is currently removing some of our shows,” she adds. .

See “Deforestation linked to changes in disease dynamics”

Allen calls the study “a comprehensive and rigorous assessment of the sustainability of the Amazon” in his comments to SMC, while noting that, “because multiple satellite sensors are used to infer the ‘lushness’ of vegetation, we must be sure that these data records show accurate trends.

“In any case, it is undeniable that human activities are waging a multi-sided war of attrition against the natural world”, he continues, “although, fortunately, in this case, the solutions are known: stop deforestation while rapidly and massively reducing greenhouse gas emissions.”


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