The drying up of the Amazon rainforest is approaching ‘tipping point’, scientists warn


By Anastasia Moloney BOGOTA, March 7 (Thomson Reuters Foundation) – The Amazon rainforest is recovering more slowly from long periods of drought over the past two decades, damaging its complex ecosystem and bringing the world’s largest rainforest one step closer to possible tipping, researchers said Monday.

A study published in the journal Nature Climate Change found that more than three-quarters of rainforest had lost its ability to recover from shocks, such as droughts and fires, and return to a healthy state. “In (forest) areas closer to human land use, such as urban areas and cropland, they tend to lose resilience faster,” said Chris Boulton, one of the report’s authors. from the Global Systems Institute at the University of Exeter.

Drier areas that receive less rainfall have also been hit particularly hard, he told an online event. Curbing the growing deforestation of the Amazon is essential to prevent the runaway effects of climate change due to the large amount of planet-warming carbon dioxide absorbed by the trees of the forest.

The researchers looked at satellite data that estimated the total amount of biomass – trees and other plants – in a given area as well as the water content of the trees and the degree of greenness of the vegetation, all indicators of health and forest resilience. They also looked at month-to-month changes as the forest responded to fluctuations in weather over a 20-year period, a long enough period to observe changes in resilience, Boulton said.

The resilience of the Amazon ecosystem in particular plummeted during the major droughts of 2005 and 2010, part of a continuing decline from the early 2000s to 2016, when the most recent data was collected, according to the study. . Scientists say dry seasons in the Amazon basin – spanning eight South American countries – have become longer and droughts have become more common and severe as climate change intensifies.

“As a result, we would expect the forest to recover from a drought more slowly now than it would have 20 years ago,” Boulton said. CLOSER TIP POINT?

As more rainforest is cut down or burned and the Amazon becomes less resilient, it could reach a tipping point where significant parts of the forest canopy are lost and become drier open savannah or more forest. shorter and drier, scientists warn. This would effectively trigger the death of the Amazon as a rainforest, the scientists said, with devastating consequences for biodiversity and climate change.

Such a change could trigger the extinction of thousands of species and the release of such a colossal amount of carbon dioxide into the atmosphere that it would sabotage global attempts to limit global climate change. It’s unclear when this critical tipping point could be reached or how long it would take for forest to transition to savannah once a tipping point is crossed, the report’s authors said.

But scientists said drier areas of the Amazon rainforest, where most resilience has been lost, are likely to reach the tipping point sooner. The satellite data collected “means we’ve probably gotten closer to that tipping point, (but) it also suggests that we haven’t passed that tipping point yet, so there’s hope,” the official said. Report author Niklas Boars, Potsdam Institute for Climate. Impact Research and Technical University of Munich, said during the online event.

Tim Lenton, director of the Global Systems Institute in Exeter and another author of the report, said the loss of resilience observed in the Amazon “is quite pronounced, clear and statistically significant”. What was also evident, he said, is that drier forests are a factor in “more intense fires that spread farther”.

Veteran tropical ecologist Daniel Nepstad, who was not involved in the report, said parts of the rainforest have already turned to scrubland, showing “a glimpse of what regional tipping points look like, in particularly in the southeastern Amazon”. “I don’t see the forest going (suddenly) to turn into savannah,” Nepstad, who heads the US-based Earth Innovation Institute, told the Thomson Reuters Foundation.

“It will be a long process of scrub – thorny scrub which increases the vulnerability of the forests,” he said.

(This story has not been edited by the Devdiscourse team and is auto-generated from a syndicated feed.)


Comments are closed.