New research suggests that this tipping point may be much closer than previously thought. According to a study published in the journal Nature Communications, 40% of the current Amazon rainforest is now at a point where it may exist as a savan rather than a rainforest.
Any change from Rainforest to Savannah will still take decades to take full effect, but once in the way the process is difficult to reverse. Rainforests support a larger range of species than savannas and play a much greater role in absorbing carbon dioxide from the atmosphere.
Some parts of the Amazon are receiving much less rainfall than they used to because of the changing climate. According to the study, under the leadership of the Stockholm Resilience Center based on computer models and data analysis, rainfall is now occurring at a level in about 40% of the forest, where rainforest can be expected to exist as a spring. is.
Last year, Brazil’s president, Jair Bolsonaro, was warned that the Amazon’s continued destruction by fires and lodgers would bring the area closer to a tipping point where the rainforest could turn into a savanna. This year’s fire at Amazon is the worst in a decade, a 60% increase in fire hotspots compared to last year.
The study’s lead author Ari Staal said that the ecology of rainforests means that although they effectively produce their own rainfall in the right climate, they are also at risk of drying out in the wrong conditions.
“As the forests grow and spread over an area, it affects rainfall,” he explained. “Forests make their own rain because the leaves give water vapor and it rains further down. Rain means less fire leads to even more forests. ”
But if large areas of the rainforest are lost, the rainfall level in this area decreases accordingly. This low level of “atmospheric moisture recycling” was simulated in the computer model used in the study.
Stall told the Guardian, “The forest conditions become harder to fix. Once the rainforest has crossed the threshold and turned into an open savanna-type mixture of wood and grassland , It is unlikely to return to its former position naturally.
“It is difficult to return from the ‘trap’ because of the feedback mechanism in which the open, grassy ecosystem is more flammable, and the fires, in turn, keep the ecosystem open,” he said.
The team of researchers ran computer simulations where forests could be expected to exist in tropical regions of the Earth, observing certain climatic conditions, and observed minimum and maximum areas of potential forest cover.
He also looked at what was likely to happen from increasing greenhouse gas emissions, and found that the ability of the forests to grow back would be greatly reduced once the trees were lost.
The paper’s co-author Ingo Fetzer of the Stockholm Resilience Center said: “We now understand that rainforests on all continents are very sensitive to global change and may lose the ability to adapt rapidly. Once gone, it will take several decades for them to recover to their original condition. And given that the rainforest hosts the most of all global species, all of this will be lost forever. “