The Amazon rainforest is reaching a critical “tipping point,” according to researchers, beyond which it may no longer be able to recover from events such as droughts and wildfires.
The result, a new analysis of satellite data shows, would be permanent loss of much of the rainforest, with devastating consequences for climate change and biodiversity.
The study, published Monday in the journal Nature Climate Change, looked at satellite data of vegetation in parts of the Amazon that have not been altered by human activities such as logging, from 1991 to 2016. It found that since the early 2000s, areas that suffered droughts or wildfires have been taking longer to recover than before, with drier areas of the forest experiencing the greatest decline.
The study’s authors warned that if climate change continues, some of these areas might stop growing back as rainforest altogether, a phenomenon known as “dieback.” This could have dramatic worldwide consequences, as it would mean that much less carbon dioxide — the most prevalent greenhouse gas that causes global warming — would be absorbed by growing trees.
“It’s worth reminding ourselves that if it gets to that tipping point and we commit to losing the Amazon rainforest, then we get a significant feedback to global climate change,” Timothy Lenton, an author of the study and director of the Global Systems Institute at the University of Exeter in the U.K., said at a news briefing.
“Many researchers have theorized that an Amazon tipping point could be reached, but our study provides vital empirical evidence that we are approaching that threshold,” said co-author Niklas Boers, a professor at the Technical University of Munich in Germany. “Seeing such a resilience loss in observations is worrying. The Amazon rainforest stores huge amounts of carbon that could be released in the case of even partial dieback.”
The Amazon covers more than 2 million square miles in South America. The destruction of the Amazon could cause the release of an estimated 90 billion tons of carbon dioxide, equal to several years of global emissions. Warmer temperatures, leading to increased water evaporation that dries out vegetation, has made its trees more vulnerable to droughts and wildfires.
The Amazon is also seeing increased deforestation under current Brazilian President Jair Bolsonaro, a right-wing advocate of logging, ranching and farming in the rainforest.
While the researchers cautioned that the many different factors involved in causing an Amazon dieback make the scenario impossible to predict with certainty, Boers said, “the Amazon is definitely one of the fastest of these tipping elements in the climate system.”
This threshold has not yet been crossed, however, meaning that if governments take swift action to reduce emissions, it could still be avoided.