Army to fight Amazon fires

Under international pressure to contain fires sweeping parts of Brazil's Amazon, President Jair Bolsonaro on Friday authorized use of the military to battle the huge blazes while thousands took to the streets to protest his environmental policies.

Brazilian forces will deploy starting Saturday to border areas, indigenous territories and other affected regions in the Amazon to assist in putting out fires for a month, according to a presidential decree.

The military will "act strongly" to control the wildfires, Bolsonaro promised.

The armed forces will collaborate with public security and environmental protection agencies, the decree says.

"The protection of the forest is our duty," the president said. "We are aware of that and will act to combat deforestation and criminal activities that put people at risk in the Amazon. We are a government of zero tolerance for crime, and in the environmental field it will not be different."

Bolsonaro has previously described rainforest protections as an obstacle to Brazil's economic development, sparring with critics who note that the Amazon produces vast amounts of oxygen and is considered crucial for efforts to contain climate change.

As the president spoke, thousands of Brazilians demonstrated in Rio de Janeiro, Sao Paulo and the capital of Brasilia demanding the government announce concrete actions to curb the fires. People also banged pots from their homes, a traditional mode of protest in South America.

Charred trees and fallen branches were seen around Porto Velho, the capital of Rondonia state, which borders Bolivia. In some instances, the burned fields were adjacent to intact livestock ranches and other farms, suggesting the fires had been managed as part of a land-clearing policy.

A large column of smoke billowed from one fire, and smoke rose from a couple of nearby wooded areas. Life appeared normal in Porto Velho. However, visibility from the windows of an arriving airplane was poor because of smog enveloping the region.

Neighbouring Bolivia and Paraguay have also struggled to contain fires that swept through woods and fields, in many cases set to clear land for farming. About 7,500 square kilometres of land has been affected in Bolivia, Defence Minister Javier Zavaleta said.

Some 370 square kilometres have burned in northern Paraguay, near the borders with Brazil and Bolivia, said Joaquín Roa, a Paraguayan state emergency official. He said the situation had stabilized.

Close to 20% of the Amazon has already been deforested, said Thomas Lovejoy, a George Mason University environmental scientist.

"I worry that the current deforestation will push past the tipping point leading to massive loss of forest and biodiversity," Lovejoy wrote in an email to The Associated Press. He said Brazil is "turning its back" on past environmental achievements, including the 1992 Earth Summit, and has proposed infrastructure projects that will accelerate the challenge of climate change.

"Fires are directly burning into the Amazon rainforest and that releases the carbon stored in those trees," said Doug Morton, a NASA scientist. "The carbon then enters the atmosphere as carbon dioxide or methane, where it contributes to the greenhouse gases that are causing climate change, bringing us a warmer and a drier planet."