Amazon Rainforest Nearing Savannah “Tipping Point”

The Amazon rainforest’s trees may soon die off en masse, researchers warn. According to a 20-year satellite study published yesterday (March 7) in Nature Climate Change, the famous forest is exhibiting signs of poor health that could mean large portions of it will become savannah in the near future. Such an ecological shift could happen quickly, Timothy M. Lenton, a coauthor on the study and a director of the Global Systems Institute at the University of Exeter, tells CNN. “My hunch, for what it’s worth, (is that) it could happen in the space of decades.”

“The Amazon is a custodian of biodiversity and possesses a vital ability to pull in carbon dioxide from the atmosphere, so it is clearly concerning that its health is deteriorating as human-caused deforestation and climate change metes out increasingly potent and harmful impacts on the ecosystem,” University of Reading climate scientist Richard Allan, who was not involved in the study, says in a statement to the Science Media Centre (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—bigger than the next two largest forests combined. Approximately one-fifth of the forest has already been lost since pre-industrial times, the study’s authors tell BBC News, and the rest is threatened by deforestation and climate change. To measure the massive forest’s resilience, researchers analyzed satellite data to determine the biomass and greenness of the forest from 1991–2006, looking for month-to-month changes in response to weather conditions. More than three-quarters of the forest exhibited reduced resilience since 2000, with trees taking longer to recover from stresses like droughts and fires. The most pronounced resilience loss occurred in areas with less rainfall and those geographically nearer to human activity, the researchers report.

“As a scientist, I am not supposed to have anxiety. But after reading this paper, I am very, very anxious,” Carlos Nobre, a climate scientist at the University of São Paulo’s Institute of Advanced Studies in Brazil who was not involved in the work, tells The Washington Post. “This paper shows we are moving in the completely wrong direction. . . . If we exceed the tipping point, that’s very bad news.”

The paper’s conclusion is similar to that of 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 in this area of potential Amazon dieback in the last two decades, with large uncertainty in model projections,” Chantelle Burton, a climate scientist at the Met Office Hadley Centre who was not involved in the research, tells the SMC. “What this study does is offer some observational-based evidence for what is already happening to this significant carbon sink, and shows that human land-use and changes to weather and climate patterns are already driving an important change in the system.”

“Passing a tipping point of this kind would make it even more difficult to achieve our goal of Net Zero emissions globally because of the loss of the “free service” provided by the Amazon carbon sink which currently removes some of our emissions,” she adds.

See “Deforestation Tied to Changes in Disease Dynamics”

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

“In any case it is undeniable that human activities are waging a war of attrition from multiple sides against the natural world,” he continues, “though thankfully in this case the solutions are known: to cease deforestation while rapidly and massively cutting greenhouse gas emissions.”

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