The fires that could reshape the Amazon

A firefighter battling flames in the Brasilia National Forest of Brazil on Sept. 4. Ueslei Marcelino/Reuters
 

 By Manuela Andreoni

 

Large parts of Brazil, a country that holds over a tenth of the world’s fresh water, are on fire. They include vast areas of the Amazon rainforest and the Pantanal, the world’s largest wetlands, as well as the Cerrado grasslands and the Atlantic forests along the country’s eastern coast.

The number of fires in the country has more than doubled compared with last year, burning an area the size of Costa Rica in August alone.

Smoke covered large parts of South America this month and blackened the skies of some of the region’s biggest cities, including Buenos Aires; São Paulo, Brazil; and La Paz, Bolivia. As if that weren’t dystopian enough, black rain from the soot produced by the fires has fallen over cities in several states in Brazil in the past few days.

In much of Brazil, fire season usually peaks this time of the year, as farmers set fire to pasture and burn recently deforested plots to clear them of unwanted vegetation. But blazes have unleashed a lot more destruction this year.

Though experts say many of the fires were very likely started by humans, the abundance of dry vegetation fueled immense blazes that grew out of control in extraordinary ways.

Almost half of the fires in the Amazon burned pristine forests, according to data from Brazil’s National Institute for Space Research. That is far from typical. It means fighting deforestation in the Amazon is no longer enough to stop fires.

This matters because it shows that the fire-control practices in some of the world’s most biodiverse places are not working. And that threatens myriad forms of life, including us. The collapse of the Amazon rainforest could release the equivalent of as much as 20 years’ worth of global carbon emissions into the atmosphere.

Deforestation and fires

The drought-depleted Madeira River, a tributary of the Amazon, in Humaita, Amazonas State, on Sept. 7. Edmar Barros/Associated Press

 

 

Deforestation is still a big problem in South America. The Cerrado grasslands, in the east of Brazil, continue to lose much of their tree cover as farmers plant soy crops that can cover areas as big as whole cities. And, while deforestation in the Amazon rainforest has slowed, it is still happening at a faster pace than the forest’s recovery rate.

Stopping deforestation should still be the priority, scientists told me. But, as the planet warms, other threats are growing.

A study from 2018 showed that, when there is drought in the Amazon, fires can increase even when deforestation goes down. That’s because drier vegetation in the form of standing trees continues to fuel the blazes.

“If fires are a direct consequence of deforestation, then a policy to fight deforestation should also be effective against fires,” said Luiz Aragão, a scientist at the space research institute and one of the authors of the study. “And what we are seeing is that it isn’t.”

Large parts of South America are under the worst category of drought. That’s partly because of natural climate patterns, such as the El Niño, which are associated with scarcer rains in the region. But global warming is probably making matters worse in the background.

Last year, scientists found that higher temperatures had made the drought in the Amazon more intense. It’s also likely that these weather patterns will change soon, as La Niña, which cools the Pacific and usually means more rain in this part of the world, sets in.

Ecosystems may change in dramatic ways

  

Part of the Brasília National Forest burning on Sept. 3. Eraldo Peres/Associated Press

 

 Looking years ahead, the situation is unlikely to improve. Humans are still burning fossil fuels that heat up the atmosphere, so extreme droughts like the current one are likely to become more frequent, scientists say.

“Maybe 2024 is the best year of the ones that are coming, as incredible as it may seem,” said Erika Berenguer, a senior research associate at the University of Oxford. “The climate models show a big share of the biome is going to become drier.”

Brazil’s environment minister, Marina Silva, recently told senators there that “we may lose the Pantanal by the end of the century,” explaining that dwindling rain and increasing heat are huge obstacles to the wetlands’ abitity to recharge to sustainable levels.

The Amazon is very likely to transform sharply if this trend continues. The forest didn’t evolve to burn like other ecosystems such as the boreal forests, Berenguer told me. The bark on its trees is thin, unlike that of redwood trees and sequoias, so even a little fire can kill them.

The types of Amazonian plants that can grow back after fires aren’t the majestic trees we associate with the rainforest, but scrubbier ones that grow and die fast and hold a lot less planet-warming carbon in their trunks.

“What the data shows is that even 30 years after fire, the burned forest still has 25 percent less carbon than a forest that never burned,” Berenguer told me.