The Amazon rainforest is nearing a “tipping point” where trees could die off en masse, researchers say.
A study suggests the world’s largest rainforest is losing its ability to recover from damage caused by drought, fires and deforestation.
Large tracts of land could become sparsely forested savannahs, which absorb carbon dioxide from the air much less efficiently than tropical forests.
The vast forest traps carbon that would otherwise contribute to global warming.
But previous studies have shown that parts of the Amazon are now emitting more carbon dioxide than it can absorb.
“The trees are declining in health and could be approaching a tipping point – basically a mass loss of trees,” said Dr. Chris Boulton from the University of Exeter.
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The findings, based on three decades of satellite data, show alarming trends in the “health” of the Amazon rainforest.
There is evidence of loss of resilience in more than 75% of forests, with trees taking longer to recover from the effects of droughts, largely due to climate change and human impacts such as deforestation and fires.
A vicious cycle of damage could trigger a “dieback,” the scientists said.
And while it’s not clear when that critical point might be reached, the impact on climate change, biodiversity and the local community would be “devastating”.
Once the process begins, it could take decades for a “significant portion” of the Amazon to transform into savannah — an entirely different ecosystem composed of a mix of grasslands and trees.
“The Amazon stores a lot of carbon and all of that would be released into the atmosphere, which would then further contribute to rising temperatures and have future implications for global average temperatures,” Dr said of the issue.
Around a fifth of the rainforest has already been lost compared to pre-industrial levels, they said.
The research was carried out by the University of Exeter, the Potsdam Institute for Climate Impact Research (PIK) and the Technical University of Munich.
“Deforestation and climate change are likely to be the main drivers of this decline,” says Prof. Niklas Boers from PIK and the Technical University of Munich.
dr Bonnie Waring, of the Grantham Institute – Climate Change and Environment, Imperial College London, commented: “These latest findings are consistent with mounting evidence that the twin pressures of climate change and human exploitation of tropical forests are threatening the world’s largest rainforest, in which is home to every 10th species known to science.”
The results, based on satellite data from 1991 to 2016, are published in the journal Nature Climate Change.
Follow Helen on Twitter @hbriggs.
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