The Amazon rainforest is losing its ability to recover from fires and droughts
The rainforest could be approaching a tipping point that would see much of the land turned into savannah.
The Amazon rainforest’s ability to recover from damaging events such as droughts and fires has consistently declined across more than three quarters of its landmass over the last 20 years.
The figure was calculated by using satellite data by researchers based at the University of Exeter, the Potsdam Institute for Climate Impact Research (PIK) and Technical University of Munich.
The team were investigating the claim that the Amazon is reaching a tipping point that could see the loss of many of its trees.
It is as yet uncertain when this critical point may be reached but as the Amazon covers an area of 6.7 million km2 and is home to one in ten species on Earth, the loss would have a major knock-on effect on biodiversity, climate change and global carbon storage.
The team used a technique that had previously been used to measure the health of the Greenland ice sheet. Its aim is to predict how close a given system is to an abrupt change by identifying a slowing down of its attributes such as its reaction to changes in weather.
They analysed two satellite data sets on biomass and the greenness of the forest and found that there was a slowing down in the restoring forces that usually bring the system back to its equilibrium after suffering damage.
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"The Amazon rainforest is a highly complex system, so it's very difficult to predict if and when a tipping point could be reached," said Dr Chris Boulton, of Exeter's Global Systems Institute.
"We now have satellite data on the Amazon that covers a sufficiently long timespan to observe changes in resilience.
"Our study looked in detail at month-to-month changes as the forest responded to fluctuating weather conditions.
"We studied metrics that are theoretically related to the rate of recovery after perturbations (external events that affect the forest), to see how the resilience of the Amazon ecosystem has changed in recent decades.
"Resilience dropped during the major droughts of 2005 and 2010, as part of an ongoing decline from the early 2000s to the most recent data in 2016.”
The team found that although average rainfall hasn’t changed significantly over recent year, dry seasons have become longer and droughts more severe.
They also found that although the overall amount of biomass has only declined slightly, the rainforest’s ability to recover from damaging events has declined much more.
"The rainforest can look more or less the same, yet it can be losing resilience – making it slower to recover from a major event like a drought," said Professor Tim Lenton, Director of Exeter’s Global Systems Institute.
"This gives new compelling evidence to support efforts to reverse deforestation and degradation of the Amazon to give it back some resilience against ongoing climate change."
Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.
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