The devastating wildfires that tore through the world’s biggest tropical wetland, Brazil’s Pantanal, in June were made at least four times more likely and 40% more intense by human-caused climate disruption, a study has found.
Charred corpses of monkeys, caimans and snakes have been left in the aftermath of the blaze, which burned 440,000 hectares (1.1m acres) and is thought to have killed millions of animals and countless more plants, insects and fungi.
The extent of the destruction exceeded the previous June record by more than 70%. This was driven by extreme fire weather that created a vast tinderbox. The month was the driest, hottest, and windiest June in the Brazilian Pantanal since observations began.
Such conditions are expected to occur once every 35 years at the current 1.2C level of global heating above pre-industrial levels, according to an international team of scientists at World Weather Attribution. If humans had not destabilised the climate by burning trees, gas, oil and coal, such extreme fire weather would have been far rarer, they said.
The once-unusual wind, heat and aridity made the fire weather conditions 40% more intense and four to five times more probable, revealed the analysis, which is based on observations of the weather as well as computer models.
The El Niño climate pattern, which faded before June, did not appear to have made a significant contribution.
These trends would grow worse in the future unless humanity stopped burning fossil fuels and forests, the scientists warned. And if global heating reached 2C, severe fire weather conditions would become about twice as likely and 17% more intense.
This is grim news for the human and non-human residents of this global centre of natural diversity. Located at the border with Bolivia and Paraguay, the Pantanal is home to many Indigenous groups and a huge range of unique species, and provides vital ecosystem services to the surrounding area, which is inhabited by tens of thousands of ranchers, farmers and fishers.
It is normally a vast carbon store, but like an increasing area of the Earth’s land, it is starting to create more emissions than in the past due to fires.
The origins of the fires are not always clear. Many start in and around areas that have been invaded or degraded by settlers. Others originate in accidents and from supposedly controlled burns that spread out of control.
Dr Clair Barnes, a researcher at the Grantham Institute, Imperial College London, said: “Climate change has supercharged the Pantanal wildfires. As fossil fuel emissions warm the climate, the wetland is heating up, drying out and turning into a tinderbox. This means small fires can rapidly accelerate into devastating ones, regardless of how they’re started.”
The team of 18 researchers said the local threat should be minimised by reducing deforestation and strengthening bans on controlled burns. But the risks remain severe because 9% of the biome has already burned this year, and the peak of the wildfire season is usually in August and September.
“This year’s Pantanal wildfires have the potential to become the worst ever,” said one of the collaborating scientists, Filippe LM Santos, a researcher at the University of Évora, Portugal, and the Federal University of Rio de Janeiro. “Even hotter conditions are expected over this month and the months ahead, and there is a considerable threat that wildfires could burn more than 3m hectares.
“Unfortunately, massive wildfires are becoming a new normal in the Pantanal. The area of wetland submerged by floodwaters is decreasing as temperatures increase, making vegetation much drier and more flammable.” Yearly rainfall in the Pantanal has been decreasing for more than 40 years.
The authors said the study – one of dozens that show destructive weather events becoming more likely and more intense around the world – highlighted the urgent need to replace fossil fuels with renewable energy.
“Our study should be taken as a warning,” said Dr Friederike Otto, a senior lecturer in climate science at the Grantham Institute. “If the world continues to burn fossil fuels, precious ecosystems like the Pantanal wetland and Amazon rainforest could pass tipping points where natural recovery from wildfires and drought becomes impossible.”
