"South American #monsoon heading towards ‘tipping point’ likely to cause Amazon dieback - ‘Shocking’ study finds #Amazon#rainforest will be unable to sustain itself and transport moisture once ‘regime shift’ occurs - The South American monsoon, which determines the climate of much of the continent, is being pushed towards a “critical destabilisation point”, according to a study that links regional rainfall to Amazon deforestation and global heating.
The authors of the report said they found their results “shocking” and urged policymakers to act with urgency to forestall a tipping point, which could result in up to 30% less rainfall, a dieback of the forest and a dire impact on food production.
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Human degradation of the Amazon – by land clearance, fire, logging and mining – is pushing that system towards a tipping point, after which drier conditions would be expected to cause an abrupt “regime shift” in the rainforest, which would be unable to sustain itself and transport moisture.
Other biomes in the region would also be affected, along with swathes of agricultural land because the monsoon stretches thousands of miles south from the Amazon to the River Plate (Rio de la Plata) basin. There would also be a climate impact because the Amazon – which would be worst affected – has historically served as an important carbon sink, though another study this week suggests it is now so degraded that it is at best carbon neutral. A dieback of the forest would release enormous amounts of carbon.
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The researchers on the Amazon-monsoon paper saw several precursors of the tipping point, including falling rainfall in many areas, the steady lengthening of the Amazon dry season, reduced soil moisture and the increasing frequency and intensity of droughts. There have been three statistically one-in-100-year droughts in the space of a single decade.
“It is shocking to see these signs of destabilisation,” said the lead author, Nils Bochow, of the University of Tromsø and the Potsdam Institute of Climate Impact Research. “But we shouldn’t lose hope. We can still act. We need stricter rules regarding the rainforest.”
