The Amazon rainforest, the planet's vast critical tropical biome, is losing its ability to recover from droughts, fires and other human activities, scientists warned in a new report published on Monday.
Affected heavily by climate change and relentless deforestation, the rainforest – which also houses at least 10% of the world’s known biodiversity – could irretrievably transition into savannah, with dire consequences for the region and the world, according to a study published in the Nature Climate Change journal.
Researchers warned that the results mean the Amazon could be approaching a so-called "tipping point" faster than previously understood. Analysing 25 years of satellite data, researchers measured for the first time the Amazon's “resilience” against shocks such as droughts and fires, which is a key indicator of overall health. This has declined across more than three-quarters of the Amazon basin, home to half the world's rainforest, according to an AFP report on the study.
Deforestation and fires have been particularly damaging to the entire region in recent years. According to a report released by the World Meteorological Organization (WMO) in August 2021, wildfires in the southern Amazon in 2020 and in the nearby Pantanal region were the worst on record, mainly due to the deadly combination of drought and human activity. These catastrophic fires made 2020 more destructive even than 2019, the previous record-holder for fire damage, according to the WMO report.
Worryingly, deforestation in Brazil has surged since far-right President Jair Bolsonaro took office in 2019, hitting a 15-year high last year, the AFP report adds. Scientists also reported recently that Brazil's rainforest – 60 percent of the Amazon basin's total – had shifted from a “sink” to a “source” of CO2, releasing 20 percent more of the greenhouse gas into the atmosphere over the last decade than it absorbed, the report explains.
But what could the "savannification" of the Amazon mean for South America and the rest of the planet? Some 90 billion tonnes of CO2 stored in its rainforest – twice worldwide annual emissions from all sources – could be released into the atmosphere, pushing global temperatures up even faster, the new study explains.
Researchers of the study – from the University of Exeter and the Technical University of Munich – looked at satellite data that estimated the total amount of biomass, trees and other plants, in a given area as well as the water content of trees and how green the vegetation appeared. These are all indicators of forest health and resilience, a Reuters report on the new study explains.
In areas hit hardest by destruction or drought, the forest's ability to bounce back was reduced by approximately half, co-author Tim Lenton, director of the University of Exeter's Global Systems Institute, told AFP. “But of course it's not just climate change -- people are busy chopping or burning the forest down, which is a second pressure point," Lenton says in the report. “Those two things interact, so there are concerns the transition could happen even earlier.”
The hotter and drier conditions have already started having a direct effect on the region’s biodiversity. These conditions – over the past four decades – have decreased the body size of the rainforest's birds while increasing their wingspans, according to a study published in the journal Science Advances in November 2021. Most species lost an average of two percent of body weight every decade. In all, the scientists investigated 77 species whose habitats ranged from the cool, dark forest floor to the sunlit and warmer midstory -- the forest's middle layer of vegetation.