A tract of Amazon jungle burns as it is cleared by farmers in Rio Pardo, Rondonia, Brazil September 15, 2019. Fire is not natural in the Amazon. Virgin rainforest, no matter how fierce the sun, is too wet to catch alight. If the forest burns it is almost always because of humans. In August, around the peak of the so-called "queimadas" as the burning season here is known, the number of fires in Brazil's Amazon jumped to its highest since 2010.

REUTERS/Ricardo Moraes

Fire is the second stage in clearing the forest, usually for raising cattle. First, choice woods are cut and sold, then the rest is burned. It is cheap, it is effective, and it is hard to catch those responsible. Cutting down the forest is illegal without permission, and using fire is against the law except in exceptional circumstances.

REUTERS/Ueslei Marcelino

Yet fire is changing the landscape. The latest data from August 2018 through July 2019 showed more rainforest was cleared than at any point in the past 11 years. An area larger than Puerto Rico was cut down. Preliminary figures suggest the rate has increased since.

REUTERS/Bruno Kelly

Three teams of Reuters journalists spent weeks traveling thousands of miles across the world's largest tropical rainforest this year, witnessing the devastation of what scientists regard as a vital protection against climate change.

REUTERS/Bruno Kelly

On the Trans-Amazonian highway, near the river port of Humaita, the August night sky did not go dark. The flames from a forest fire, stretching into the distance beside the road, glowed a dusky yellow. For days it burned.

REUTERS/Ueslei Marcelino

Some people have taken protecting the forest into their own hands. Reuters spent seven days with an indigenous vigilante group fighting to keep illegal loggers off their land in the state of Maranhao.

REUTERS/Ueslei Marcelino

One night in September, alerted by the rumble of heavy trucks, six Guajajara tribesmen -- faces painted for battle -- rushed to ambush a group of loggers. At a choke point in the local network of rutted dirt roads, they lay in wait, a 4x4 blocking the road, rifles and handguns at the ready. When the trucks arrived, the loggers, who numbered around eight, were first to fire. The Guajajara shot back, forcing the loggers to scatter into the forest. The indigenous warriors burnt the trucks, piled high with freshly cut lumber.

REUTERS/Ueslei Marcelino

A Guajajara Indian "forest guardian" draws water from a well at a loggers camp on Arariboia indigenous land near the city of Amarante, Maranhao state, Brazil, September 11, 2019. REUTERS/Ueslei Marcelino

One of the men that night was Paulo Paulino Guajajara. He knew it was dangerous work and spoke frankly of his fear. "I'm scared at times, but we have to lift up our heads and act. We are here fighting," he said. Four weeks later, he was dead. Members of his tribe said loggers had shot him through the head.

REUTERS/Ricardo Moraes

An aerial view shows smoke rising over a deforested plot of the Amazon jungle in Porto Velho, Rondonia State, Brazil, August 24, 2019. REUTERS/Ueslei Marcelino

An aerial view shows a tract of Amazon jungle burning as it is cleared by farmers in Itaituba, Para, Brazil September 26, 2019. REUTERS/Ricardo Moraes

An aerial view of a deforested plot of the Amazon in Boca do Acre, Amazonas state, Brazil August 24, 2019. REUTERS/Bruno Kelly

An aerial view shows a deforested plot of the Amazon near Porto Velho, Rondonia State, Brazil, September 17, 2019. REUTERS/Bruno Kelly

An aerial view of a burned tract of Amazon jungle as it was cleared by loggers and farmers near Porto Velho, Brazil August 29, 2019. REUTERS/Ricardo Moraes

Eliane Muller, 40, walks next to a burnt tract of the Amazon forest as it is cleared by farmers, after the fire hit 2 acres from her cassava plantation in Rio Pardo, Rondonia, Brazil September 16, 2019. REUTERS/Ricardo Moraes

The carcass of a cow lies along a tract of the Amazon jungle as it is cleared by loggers and farmers in Porto Velho, Brazil August 24, 2019. REUTERS/Ueslei Marcelino

A cow is seen amid smoke from a burning tract of the Amazon jungle as it is cleared by loggers and farmers in Apui, Amazonas state, Brazil September 3, 2019. REUTERS/Bruno Kelly

An Indigenous named Pedro Mura from the Mura tribe reacts in front of a deforested area in nondemarcated indigenous land, inside the Amazon rainforest near Humaita, Amazonas State, Brazil August 20, 2019. REUTERS/Ueslei Marcelino

Employees relax in a camp inside the Bom Retiro deforestation area on the right side of the BR 319 highway near Humaita, Amazonas state, Brazil September 20, 2019. REUTERS/Bruno Kelly

Jose, 2, plays while a fire burns a tract of Amazon jungle as it is cleared by loggers and farmers near Porto Velho, Brazil August 27, 2019. REUTERS/Ricardo Moraes

A Brazilian Institute for the Environment and Renewable Natural Resources (IBAMA) fire brigade member attempts to control hot points during a fire at Tenharim Marmelos Indigenous Land, Amazonas state, Brazil, September 15, 2019. REUTERS/Bruno Kelly

A fire burns a tract of Amazon jungle near Porto Velho, Brazil September 9, 2019. REUTERS/Bruno Kelly

A burning tree is seen during a fire in an area of the Amazon rainforest in Itapua do Oeste, Rondonia State, Brazil, September 11, 2019. REUTERS/Bruno Kelly

Brazilian Institute for the Environment and Renewable Natural Resources (IBAMA) fire brigade members are seen as they attempt to control hot points during a fire at Tenharim Marmelos Indigenous Land, Amazonas state, Brazil, September 15, 2019. REUTERS/Bruno Kelly

A tract of Amazon jungle burns at Tenharim Marmelos Indigenous Land, Amazonas state, Brazil, September 15, 2019. REUTERS/Bruno Kelly

Smoke billows during a fire in an area of the Amazon rainforest near Porto Velho, Rondonia State, Brazil, September 10, 2019. REUTERS/Bruno Kelly