Brazil wildfires worsened by ‘megadrought’ and extreme heat – DW – 08-30-2024

Some 2,700 fires have raged in the southern Brazilian state of Sao Paulo over the past week, with more than 40 communities on high alert, with the state capital and other cities shrouded in heavy, gray smoke.

At last count, authorities said more than 59,000 hectares (about 146,000 acres) had been burned by the flames, an area the size of Chicago. This included vast swaths of sugar cane fields, one of the country’s top exports.

The federal police suspect arson as the cause of the fires. The fires started at several locations at the same time and spread quickly through bone-dry vegetation in a region where it has not rained for months.

“We have had an explosive combination of three factors in recent days: high temperatures, very strong winds and very low relative humidity,” São Paulo Governor Tarcisio de Freitas said Tuesday.

Extreme heat and drought fuel fires

The dry season in Brazil usually lasts from August to October. But climate experts with the World Weather Attributiona group of scientists who study the effects of climate change on extreme weather, said last June was the “driest, hottest and windiest” month in the country since records began in 1979.

Those conditions have left the state of Sao Paulo and the Amazon rainforest further north facing their worst fire season in decades. In August, Sao Paulo recorded more than 3,480 separate fires, double the number for all of 2023. And in the first six months of 2024, the Amazon has seen its highest number of fire outbreaks in 20 years.

These same extreme conditions have also fueled record fires in the Cerrado Plateau, a tropical savanna, and the Pantanal, the world’s largest tropical wetland, a biodiverse area teeming with species of plants and animals. The Pantanal, located between the Amazon and Sao Paulo, lost some 600,000 hectares to flames in June, an area the size of Luxembourg.

About 20% of the Amazon rainforest has already disappeared

In an early August report, WWA said fires in the Pantanal were “40 percent more intense due to climate change.” The data bears this out: Annual rainfall in the wetlands has been steadily declining for more than 40 years.

“These massive droughts are becoming more frequent and more severe,” said Carlos Peres, a Brazilian conservation expert at the University of East Anglia in the United Kingdom, adding that about three-fifths of Brazil is becoming increasingly drier.

Using satellite image analysis, the Brazilian environmental institute MapBiomas revealed in June that the Amazon and Pantanal regions “experienced severe water reductions.” The Amazon rainforest experienced a historic drought from June to November 2023, caused by low rainfall and persistently high temperatures. But the Pantanal biome dried out the most in 2023, with a 61% decrease compared to the historical average of 1985.

Peres grew up as the son of a cattle rancher in the state of Para in the 1960s and 1970s, on the eastern edge of the Amazon rainforest. In his lifetime, he has seen the Amazon shrink by about 20 percent. And with that loss of forest, some of what remains is increasingly going up in flames.

“Up until about 25 years ago, forests in the Amazon, even if they were on sandy soils and seasonally dry areas, would not burn unless there was some kind of human disturbance, like logging,” Peres said. “But that has changed.”

He said that successive droughts and shorter rainy seasons do not give the ground enough time to fill with water, making the vegetation above it more vulnerable to fires. Luciana Gatti, who leads a group of researchers at INPE, Brazil’s National Institute for Space Research, told DW from Sao Paulo that the problem is only getting worse.

“We are accelerating the climate crisis,” Gatti said, stressing that deforestation was doing more to raise temperatures in the Amazon than global climate change. “The forest that is left is not the same; it is as if the Amazon is sick.”

Trees and other plant life act as climate regulators, absorbing planet-warming carbon dioxide but also releasing water vapor into the air through a process called evapotranspiration. In Brazil, Gatti said, water evaporating from the Amazon and Pantanal wetlands acts as a “climate buffer,” helping to cool the atmosphere. But with increasing wildfires and deforestation, that buffer is weakening.

In a 2021 study published in the journal NatureGatti wrote that parts of the southeastern Amazon have even begun to act as a source of carbon dioxide, rather than absorbing it as usual. And, she said, while deforestation has slowed somewhat in recent years, forest degradation from fire and other factors has gotten worse. “And the problem is that the fire is more and more uncontrolled each time.”

Fire and drought ‘more often’

“These extreme events are becoming more and more common,” said Julia Tavares, a Brazilian plant ecologist and postdoctoral researcher at Sweden’s Uppsala University. In a 2023 studyShe and her fellow researchers investigated how different parts of the rainforest responded to the warmer, drier conditions. They found that parts of the Amazon rainforest were coming under increasing pressure.

The World Resource Institute reports that wildfires around the world are getting worse, destroying twice as many trees as 20 years ago. And a 2022 report from the UN Environment Programme predicted that extreme fires would increase by 30% by 2050.

However, Tavares said that the changing climate was not the direct cause of the fires in Brazil, adding that natural fires are very rare in tropical climates.

“It’s caused by humans, human actions that are amplified by climate change, because you have better conditions for fire to spread,” she said, highlighting the vast swaths of land, often cleared by ranchers and farmers who set fires using a technique known as slash-and-burn agriculture, that are continually nibbling away at the pristine rainforest.

“Things are changing very quickly,” said Peres, outlining how increased fires and droughts were threatening water and food security and wiping out biodiversity. and be harmful to human health.

He pointed out that every time a forest burns, it sets the stage for “more frequent and intense fires the next time,” as more vegetation dies and becomes fuel for the next forest fire.

“By the time the forest burns for the third time, you have no forest left,” Peres said. “And the damage that does, both in terms of loss of biodiversity and loss of carbon storage, is enormous.”

Edited by: Jennifer Collins