Last week, around 2,700 fires raged in the southern Brazilian state of São Paulo. More than 40 municipalities were on high alert, and the state capital and other cities were shrouded in thick, gray smoke.

According to the latest calculations by the authorities, more than 59,000 hectares of land were destroyed by the flames, an area the size of Chicago. This included large areas of sugar cane fields, one of the country’s most important exports.

The federal police suspect arson as the cause of the fires, which broke out simultaneously in different locations and spread quickly through the dry vegetation of 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,” said São Paulo Governor Tarcisio de Freitas on 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 studying the impact of climate change on weather extremes said last June was the country’s “driest, hottest and windiest” month since weather records began in 1979.

Under these conditions, the state of Sao Paulo and the Amazon rainforest further north experienced the worst fire season in decades. In August, more than 3,480 individual fires were recorded in Sao Paulo, twice as many as in all of 2023. And in the first six months of 2024, the Amazon region saw the highest number of fire outbreaks in the last 20 years..

The same extreme conditions have also fuelled the record-breaking fires in the Cerrado plateau, a tropical savannah, and in the Pantanal, the world’s largest tropical wetland, an area rich in biodiversity and animal and plant species. In the Pantanal, between the Amazon and Sao Paulo, around 600,000 hectares were lost in flames in June, an area the size of Luxembourg.

About 20 percent of the Amazon rainforest has already disappeared

A report from early August said that fires in the Pantanal were “40 percent more intense due to climate change.” The data proves this: annual rainfall in the wetlands has been steadily declining for over 40 years.

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

By analyzing satellite images, the Brazilian environmental institute MapBiomas In June, it was announced that the Amazon and Pantanal regions were “facing a serious water shortage.” The Amazon rainforest experienced a historic drought from June to November 2023, due to low rainfall and persistent high temperatures. But the Pantanal biome dried out the most in 2023, recording a 61% decline compared to the 1985 historical average.

Peres grew up in the 1960s and 1970s as the son of a cattle rancher in the state of Pará on the eastern edge of the Amazon rainforest. Over the course of his life, he has witnessed how the Amazon has shrunk by around 20 percent. And with this loss of forest, more and more of the remaining forests are going up in flames.

“Until about 25 years ago, forests in the Amazon region did not burn, even if they were on sandy soil or in seasonally dry areas, unless there was human intervention such as logging,” says Peres. “But that has changed.”

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

“We are accelerating climate collapse,” said Gatti, stressing that deforestation is contributing more to the rise in temperature in the Amazon than global climate change. “The remaining forest is no longer the same; it is as if the Amazon is sick.”

Trees and other plants act as climate regulators by absorbing carbon dioxide, which warms the planet, but also by releasing water vapor into the air through evapotranspiration. In Brazil, says Gatti, the water evaporating from the wetlands of the Amazon and Pantanal acts as a “climate buffer” and helps cool the atmosphere. But as forest fires and deforestation increase, this buffer is weakening.

In a 2021 study published in the journal NatureGatti wrote that parts of the southeastern Amazon were even acting as sources of CO2, rather than absorbing it as usual. And while deforestation has declined somewhat in recent years, forest degradation from fire and other factors has worsened, she said. “And the problem is that the fires are becoming more uncontrolled each time.”

Fires and droughts “more frequent”

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

The World Resources Institute reports that forest fires around the world are getting worse, destroying twice as many trees as they did 20 years ago. And a 2022 report by the UN Environment Programme Extreme fires are forecast to increase by 30% by 2050.

However, Tavares said that climate change was not the immediate cause of the fires in Brazil. Naturally occurring fires are very rare in a tropical climate.

“The causes are people, human activity, which is exacerbated by climate change because it creates better conditions for fire to spread,” she said, pointing to the vast areas of land that are often cleared by ranchers and farmers who set fires using a technique known as slash-and-burn, constantly destroying pristine rainforest.

“Things are changing very quickly,” Peres said, explaining how increasing fires and droughts are threatening water and food security and wiping out biodiversity. and harm human health.

He pointed out that each wildfire lays the foundation for “more frequent and more intense fires the next time” because more vegetation dies and becomes fuel for the next wildfire.

“If the forest burns for the third time, there will be no forest left,” Peres said. “And the damage this causes, both in terms of biodiversity loss and carbon storage, is enormous.”

Edited by: Jennifer Collins