Has the Amazon Reached Its ‘Tipping Point’?
Eventually Gatti pulled off to the right, through a tunnel of overhanging branches and into an open area where tall trees shaded a research base built as part of Nobre’s L.B.A. The base resembled an eco-lodge, with low-slung wooden buildings topped by clay-tiled roofs. Night was falling, the roar of frogs competing with the distant howl of monkeys. We were met by a 39-year-old biologist, Erika Berenguer, who wore an old white T-shirt, overlarge and dirty. Her specialty, she said, was desgraça — calamity. It turns out that deforestation numbers actually understate the problem of the Amazon, because a fifth of the standing forest has been “degraded” by logging, burning and fragmentation. Now based in Oxford, Berenguer has spent the last 12 years studying how these ills affect the Amazon’s ability to store carbon. As she would explain, though, even she was shocked by what happened in 2015, a critical turning point in the health of the ecosystem.
At the time Berenguer’s project was to measure every single tree in a few dozen plots in and around the Tapajós National Forest, at regular intervals, to calculate the weight of all the organic matter, or biomass, which serves as a proxy for carbon. At first, when she noticed flames inside the conservation area, she just kept doing her work — gathering up leaf litter, fixing tape around centuries-old trunks, tagging each one with numbered scraps of metal sliced from beer cans. As Berenguer’s colleague Jos Barlow likes to point out, outside observers usually fail to distinguish between deforestation fires (intentionally set to clear freshly clear-cut areas) and wildfires (when the flames accidentally spread to standing forests). Now it was August, the height of the dry season, when ranchers and farmers in the Amazon clear fields with fire. Almost every year, embers floated across the BR-163 highway, igniting leaves on the forest floor. But the forest itself remained so damp that the flames could not spread far.
Berenguer, a native of cosmopolitan Rio de Janeiro, made a point of sweating alongside her assistants, local men with nicknames like Xarope (Syrup) and Graveto (Stick), whose families had settled by the BR-163 as part of the colonization push of the 1970s. They were not too concerned, either. As subsistence farmers, they also used fire to maintain their lands. It is a tradition that dates back to the region’s oldest inhabitants, Indigenous people who discovered that ash fertilizes the nutrient-poor soils. Outside the rarest of megadroughts, they never had to worry about losing control of the flames. Researchers have found areas of the Amazon that, according to sediment core samples, went 4,000 years without a single burn.
As Berenguer worked through September, however, the smoke from disparate fires coagulated into a permanent, indistinguishable haze. It permeated everything — their truck, their clothes, even Berenguer’s bra. When they kicked away dead leaves, they noticed that the soil beneath was cracking. The little plants of the understory wilted. Soon everyone was coughing; people took turns breathing mist from a nebulizer, and her own snot turned black. Each morning, she and her assistants had to clean a layer of fresh soot from the windshield of their truck. They turned the brights on, turned the emergency lights on and edged onto the highway. They drove slowly but couldn’t see vehicles ahead until they were nearly colliding with them. The sky was hidden. The sun was a red suggestion. Ash fell like alien snow.
The fires were escaping to crop gardens, to pastureland where cattle grazed, to the thatched roofs of houses. And the fires were doing what they should not: spreading inside the rainforest. Splitting her time between Britain and the Amazon, Berenguer had come to know her research plots as intimately as her old neighborhood in Rio. She thought of her favorite places as rainforest versions of her local coffee shop, her local bakery. There were the fallen logs where she and her assistants returned day after day so they could sit and eat lunch. There were the tall, thin buttress roots that acted as a makeshift bathroom stall, hiding her from view when necessary. In one plot, a thick loop of liana hung from the canopy, making for the perfect swing. Now she wanted to save these places.
Among the great old trees of the Tapajós, the flames rose a mere foot from the ground. Berenguer and Xarope could stamp them out with their boots. But their efforts were in vain. The flames consolidated into a thin, uninterrupted arc that stretched for miles into the forest. It advanced slowly, a thousand feet per day; in its wake, the rich perennial green was left brown and gray and charcoal-black. Berenguer watched as animals fled from the fire line — butterflies, deer, thumbnail-size frogs. One day she surprised a snake. It leaped onto a smoldering trunk, accidentally immolating itself, and Berenguer heard a sizzling sound, like buttered bread hitting a griddle plate.