The fate of rainforests is critical to the health of the planet, as they are home to a unique array of animals and plants, store vast amounts of carbon, and greatly influence global weather patterns.
Scientists say about three-quarters of rainforests are showing signs of “gross resilience” – a reduced ability to recover from disruptions such as droughts, logging and fires. Their study is based on monthly observations of satellite data over the past 20 years, which mapped the forest’s biomass (organic material) and greenery to show how it has changed in response to fluctuating weather patterns.
This decline in resilience since the early 2000s is a warning sign of irreversible decline, the authors say. While it is impossible to say exactly when the transition from rainforest to savannah might occur, once it becomes apparent it will be too late to stop.
“It’s worth reminding ourselves that if it comes to a tipping point and we make the decision to lose the Amazon rainforest, then we will have a significant response to global climate change,” Timothy M. Lenton, one of the authors of the new study and director, said at a briefing Fellow at the Global Systems Institute at the University of Exeter in the UK.
“We are losing about 90 billion tons of carbon dioxide, mostly in trees, but also in the soil (of the Amazon),” Lenton said.
If the Amazon is no longer a rainforest, it won’t store as much carbon.
Previous studies based on computer simulations have reached similar conclusions about the ecological point of no return for the Amazon rainforest, but the authors said their study, published in the journal Nature Climate Change on Monday, used real-world observations.
The authors say that once we reach the tipping point, the rainforest could disappear fairly quickly. “My hunch, whatever it takes, (is it) it could happen within decades,” Lenton said.
The study found that the loss of resilience was most noticeable in areas close to human activities, as well as those that received less rainfall. The study also notes that the loss of resilience does not mean loss of forest cover, meaning that the rainforest may be close to the point of no return without well-defined change.
Shantel Burton, senior scientist at the Met Office’s Hadley Center in the UK, said how the Amazon rainforest will withstand the challenges of climate change, land use and fire remains a matter of question. She said this new study was “really important.”
“This study offers some observational data about what is already happening with this significant carbon sink and shows that human land use and changes in weather and climate patterns are already causing important changes in the system,” Burton. who was not involved in the study, told the Science Media Center in London.
“Passing this kind of tipping point will make it even more difficult to achieve our goal of reducing Net Zero emissions globally due to the loss of ‘free services’ provided by Amazon’s carbon sink, which is currently removing some of our emissions.”
Richard Allan, professor of climatology at the University of Reading, said the study is a “comprehensive and rigorous assessment of the longevity of the Amazon.”
“We have come to the tempting conclusion that much of the Amazon is showing signs that it may be approaching a tipping point towards irreversible decline; but since several satellite sensors are used to determine the “violence” of vegetation, we must be sure that these data records show accurate trends, ”Allan was quoted as saying by SMC.
“In any case, it cannot be denied that human activity is waging a war of attrition from different sides against the natural world, although, fortunately, in this case the solutions are known: stop deforestation while reducing greenhouse gas emissions rapidly and massively.”