Georgina Gustin writes:

The world’s largest rainforest is losing its ability to bounce back from droughts and fires, pushing it farther toward a threshold where it could transform into arid savannah, releasing dangerous amounts of greenhouse gases in the process.

A study published Monday in the journal Nature Climate Change found that the Amazon has become less resilient as deforestation has continued and rising temperatures have worsened drought. The authors said the rainforest’s ability to recover from such events has diminished across three-quarters of its area in the last two decades, especially in parts that are closer to human activity, like urban areas and croplands.

“We’ve found a pronounced loss of Amazon rainforest resilience over the last 20 years,” said Chris Boulton, a climate scientist with the University of Exeter and a co-author of the report. “And when I say resilience, I mean the ability of the Amazon rainforest to restore itself back to a stable state.”

The study adds to a mounting pile of research projecting that the Amazon will reach a point when it rapidly converts into a different, drier ecosystem, although the timing of this “tipping point” remains uncertain and whether it will encompass the entire rainforest is also debated. The authors of the new study have said the change could come within decades. They were reluctant to be more specific, but said the tipping point could be sooner even than current models suggest.

“The core idea is, if the system is heading toward a tipping point, where by definition it’s getting less stable, this means that before that happens, it gets slower recovering from all these perturbations, like the drought events that are happening year to year,” said Tim Lenton, a professor of climate science at the University of Exeter and a co-author of the study. [Continue reading…]