After four decades of research, a scientist returns to the Amazon in an effort to change the behavior that has lead to years of environmental crisis.

Stopping the Greatest Threat to the Amazon, One Fire at a Time

After four decades of research, a scientist returns to the Amazon in an effort to change the behavior that has lead to years of environmental crisis.

• Nov. 22, 2025

Daniel Nepstad first set fire to the Amazon rainforest in 1985.

He was a young researcher at the time, studying how tropical forests remained so lush, even during the dry season. “I became obsessed with the incredible ability of these forests to endure drought,” he said.

After years of experiments, including numerous attempts to intentionally light the Amazon aflame, he arrived at a surprising conclusion: “Forests are pretty hard to burn down.”

Much has changed since then.

As climate change has pushed global temperatures to record levels, the Amazon has become increasingly combustible, creating years of rolling environmental crisis.

Persistent heat makes it harder for vegetation to retain moisture, which in turn makes it easier for forests to burn. On top of that, the vast majority of fires in the Amazon are set by humans, particularly by farmers clearing land for agriculture. Fire begets fire.

Last year, a record amount of tropical primary forests burned around the globe, according to the World Economic Forum, five times as much as the prior year’s level of forest loss. In the Amazon, fires consumed an area larger than California.

Now Mr. Nepstad is returning to the Amazon to try to stop fires in a region that scientists have identified as a critical bulwark against global warming.

“Fire is the biggest threat to the Amazon, but it’s also a problem that’s possible to solve,” Mr. Nepstad said. “This is the biggest climate solution that could happen over the next new years.”

Working through his own nonprofit organization, the Earth Innovation Institute, along with a coalition of other groups, local business leaders and international research groups, Mr. Nepstad is trying to encourage small shifts in behavior that might help stop fires before they begin.

The changes he is asking farmers to make can be modest: planting different crops, letting forests return and pooling resources to afford machinery that can clear land instead of resorting to intentional burns. Yet in the aggregate, he believes these modifications can have a major effect.

Dan Nepstad stands inside the protected forest of Fazenda Vitória; plowing a swath of deforested Amazon rainforest on a farm near Paragominas; cattle on restored pasture at Fazenda Vitória.

On a recent weekend, ahead of his participation the United Nations climate summit in Belém, Brazil, Mr. Nepstad, a tropical ecologist, returned to Paragominas, the city where he began his research 41 years ago.

Mr. Nepstad and his team spent days traveling to remote farms with just a few dozen head of cattle and to large ranches with thousands of cows, explaining how different farming practices could reduce the risk of fire and help land be more resilient when flames arrive.

Fires in Brazil have grown worse in recent years. Last year, they swept across the Pantanal, the world’s largest wetlands. After seasonal rains failed to materialize last year, a record number of fires charred the Amazon. Five years earlier, in 2019, another bad fire season consumed vast tracts of land.

All these blazes present myriad challenges. When virgin rainforest burns, it takes a toll on biodiversity. When agricultural land burns, it affects the livelihoods of the more than 40 million people who live in the Amazon.

The fires also release vast quantities of stored carbon dioxide into the atmosphere, accelerating global warming.

This marks a stark reversal of an age-old trend. In recent centuries, the Amazon acted like a filter, absorbing many of the planet-warming emissions from the burning of fossil fuels like coal, oil and gas.

But some of this area is no longer a reliable carbon sink. In recent years, parts of the Amazon that have been developed into farmland, including the area where Mr. Nepstad started his career, now produce more carbon dioxide than they absorb.

Left unchecked, scientists warn that the loss of Amazon to fire and deforestation could lead to irreversible changes, leading to much of the forest giving way to grasslands and further accelerating global temperature rise.

“We have had record-breaking fires in the Amazon,” said Carlos Nobre, a Brazilian scientist who has spent his career studying the region. If Brazilians aren’t able to get the fires under control, Dr. Nobre said, “the Amazon will cross the tipping point.”

Image

Dr. Nepstad blowing on a leaf cutter ant’s nest to see if it is active in the protected forest at Fazenda Vitória, near Paragominas.

Mr. Nepstad set out from Belém at 5 a.m. on a Saturday morning and started driving south in a pickup truck, crossing the Guamá River as the sun rose.

A century ago, this part of the Amazon was largely untouched. Thick forest covered the nearly half-million square miles that today make up the state of Pará, which sits on the Equator and includes the mouth of the Amazon River.

That all changed in the second half of the 20th century, when the Brazilian government began building a series of highways across the rainforest in a bid to open up land for economic development. And by the late 1970s, more farmers were intentionally setting fires to clear land for agriculture.

After a seven-hour drive through fields of soybeans destined for China, palm trees that will become palm oil and eucalyptus trees that will be turned into paper, Mr. Nepstad pulled into a the tiny village of Formosa, a poor settlement deep in Amazonian farmland.

For years, the farmers in Formosa and other nearby settlements have intentionally set fires to clear their land for cattle ranching and crops like cassava. But those fires are increasingly difficult to control, and have been escaping and spreading to nearby forests and farms.

Inside a community building, 50 people had gathered to listen to Mr. Nepstad and his team pitch their fire prevention plan.

One of Mr. Nepstad’s partners was Maxiely Scaramussa Bergamin, the president of the rural farmer’s union. Ms. Bergamin spoke about the benefits of growing in-demand crops like açaí and cacao. In addition to selling for a premium, these plants can displace cattle and, in turn, help stop intentional fires from spreading.

Maxiely Scaramussa Bergamin, president of the farmers’ union; Gleyciany Sobral de Souza, whose audience included Dr. Nepstad, left, speaking during a community meeting; Samuel Silva harvested açaí near Paragominas.

A team of firefighters addressed the audience, explaining how they could use a new mobile alert system to raise the alarm if they spotted an uncontrolled fire burning nearby.

Finally Mr. Nepstad explained how his history of research had led him to arrive at this singular focus on stopping fires. The goal, he said, was to kick-start a virtuous cycle of farming practices that would reduce wildfires. “If small holders can shift to systems that don’t need fire, everybody is better off,” he said.

After the community served its guests a lunch of açaí, pork and plantains, Mr. Nepstad and his team reconvened to hear stories from the farmers about their experience with fire.

Gleyciany Sobral de Souza said that last year, she watched five hectares of açaí burn, losing crops that could have been worth as much as $100,000. “I’ve lost it,” she said. “When it’s dry, it doesn’t grow back.”

Francisca Risalva Romao de Souza, another farmer, said recent blazes had charred her land and killed a cow. “People are more afraid to use fires these days,” she said.

And Waldir Silva, who has used fire his whole life, said he is trying not to anymore. “The biggest challenge is to balance production with preservation of the environment,” he said. “You can’t balance anything with fire.”

Changing habits in villages like Formosa will take time, but Mr. Nepstad says he has confidence that reform is possible.

A firefighter and firefighting work on a degraded piece of pasture land in Paragominas.

Thirty years ago, Paragominas was once the largest producer of timber in the world. There were more than 300 sawmills operating as loggers cleared the Amazon for lumber.

Today most of the sawmills are closed, and bit by bit, the forest is slowly coming back.** **In 2008, 64 percent of the county was covered in forest. Today, that figure is up to 68 percent.

But the fires are never far away. It had not rained in a month, and the land was poised to burn.

As the conversations wound down, a group of firefighters who receive funding from Mr. Nepstad’s nonprofit organization put a drone up in the air. Scanning the horizon through a tiny monitor, one of firefighters saw smoke in the distance.

In a matter of minutes, they had packed up their gear, piled into their truck and headed toward the hot spot.

Image

Protected forest amid pasture at Fazenda Vitória, near Paragominas.

Starting in 1984, Mr. Nepstad began his research career on a cattle ranch outside Paragominas called Fazenda Vitória.

The owner of the land, Percio Barros de Lima, raises thousands of cattle on a vast expanse of pastures. Yet in the middle of the property is an island of almost untouched rainforest, just a few square miles of the Amazon as it once was.

It was on this land that Mr. Nepstad discovered that the roots of Amazonian trees stretch down more than 20 meters, and that when covered with forest, the land acts like a sponge, retaining moisture that can help it endure lengthy droughts and even some fires.

That led to a series of experiments where Mr. Nepstad tried to burn the forest down, sometimes throwing lit cigarettes into piles of leaves on the ground to see if they would ignite. They almost never did — tropical moisture swallowed up the sparks in a matter of minutes.

After visiting Formosa, Mr. Nepstad returned to Fazenda Vitória for the first time in a decade. As he emerged from the truck, he and Mr. de Lima embraced, then set out for a walk into the trees.

Although Mr. Nepstad had encouraged Mr. de Lima to preserve the forest over the years, he was unsure what he would find as he returned.

Mr. de Lima said he had plenty of opportunities to wipe away the rainforest in his backyard. During the heyday of the local logging industry, it could have been cleared for timber. And like so many of his neighbors, he could have cleared the land with fire to make way for more cattle.

But as he set out, Mr. Neptsad was heartened to find his old living laboratory intact. He pointed out a giant ipe tree, a sign of original forest, with a towering crown that burst through the canopy. Nearby was an enormous piquia that Mr. Nepstad estimated to be between 500 and 700 years old.

A creek in the Fazenda Vitória; Percio Barrios de Lima, a rancher, with Dr. Nepstad; and a piquia tree, estimated by Dr. Nepstad to be 500 to 700 years old, in the protected forest of Fazenda Vitória.

While this patch of rainforest is small, it is still home to tapirs, jaguars, ocelots, anteaters, porcupines, bush dogs, howler monkeys, scarlet macaws, toucans, vampire bats, sloths and boa constrictors.

Mr. de Lima said he was proud of this small act of conservation. “I had a chance to chop it down and turn it into housing, and I’m so relieved that I didn’t,” he said. “Whenever I am in this forest, I feel this contentment.”

But last year, a blaze came to the edge of the forest. It was unclear how it started, but a likely culprit was a discarded cigarette from a passing truck that sparked a major blaze in today’s hotter, drier Amazon.

“Fire is the biggest challenge now,” Mr. de Lima said. “We’d never seen a drought like last year.”

Mr. Nepstad confessed he was surprised to see the tall trees still standing.

“I assumed this forest would all be gone,” he said. Mr. de Lima, he said, “had dollar signs in his eyes back then, but he became this incredible land steward.”

Even more surprising was the fact that there was new forest where there had been none just a decade ago. As Mr. de Lima has worked to concentrate his cattle on a smaller area of land, he has let the trees reclaim former pasture. Previously barren stream beds were filling in with vegetation, and more animals were returning to the land.

Decades after he began his work, the Amazon had taught Mr. Nepstad another lesson. “One of the surprises for me is just how tough the forest is,” he said. “It keeps bouncing back.”

Advertisement

SKIP ADVERTISEMENT