Tropical Forests Are Flipping From Storing Carbon to Releasing It | The Nation

Mushrooming disaster: Thanks to logging, cattle ranching, and industrial agriculture, 16 percent of the Amazon has already been deforested. (Sam Eaton)

Illegal logging and land seizures are driving this ominous yet overlooked scientific trend.

By Sam Eaton

August 30, 2018

it wasn’t until heavily armed men arrived from across the river that Cláudio José da Silva realized who was bankrolling the latest episode of illegal logging. His bare chest traced with blue-black lines of body paint, da Silva is a member of the Guajajara people in eastern Brazil, one of the country’s largest indigenous groups. Their side of the Carú River is pristine Amazon rain forest. Across the river, the rain forest has been razed and replaced by cattle ranches and farms. On paper, the Guajajaras’ nearly 700 square miles of rain forest are protected as federally recognized indigenous territory. In reality, the group lives under constant threat of theft and violence. Just the day before, da Silva’s self-defense force, the Guardians of the Forest, caught the local sheriff’s son using cattle to drag lumber from their forest. Armed with machetes, they chased him away and confiscated the cows. Now the sheriff had come bearing an ultimatum: Return the cattle or his posse would retrieve them by force.

The reporting for this project was produced in partnership with PBS NewsHour and the public-radio program PRI’s The World, with support from the Pulitzer Center and the Society of Environmental Journalists.

“This struggle, for us, is war,” da Silva says. He claims to have received dozens of death threats since founding the Guardians of the Forest in 2012. “The loggers carry arms. The farmers are armed. They want confrontation.” Indeed, on August 12, a month after I visited da Silva, the dead body of his comrade, Jorginho Guajajara, was found in a nearby river.

Violent conflicts over land and logging have spilled blood throughout the Amazon since the 1980s, when the murder of the organizer Chico Mendes made international headlines. Brazil is the deadliest country in the world for land defenders, with more than 140 killings since 2015, according to the NGO Global Witness. The state of Maranhão, where the Guajajara live, is perhaps the most dangerous: In 2016, more attacks on indigenous groups occurred there than anywhere else in Brazil, according to the Pastoral Land Commission.

Apart from the human toll, the violence in the Amazon is also driving an ominous trend in the earth’s climate system. Last October, Science published one of the most important—and least noticed—climate studies in years. Tropical forests in the Amazon and around the world have been so degraded by logging, burning, and agriculture that they have started to release more carbon than they store, according to scientists from the Woods Hole Research Center and Boston University. In the parlance of climate change, these forests are flipping from carbon sinks to carbon sources.

This is very bad news, for two reasons. First, until now, the capacity of forests to absorb carbon dioxide via photosynthesis has been a crucial buffer against greenhouse-gas emissions: The forests’ absorption of CO2 has limited the global temperature rise to considerably less than it would otherwise be. Second, forests must absorb even more carbon going forward if humankind is to contain that temperature rise to a survivable amount. Current trends put the earth on a trajectory to an increase of 3.5 degrees Celsius, an amount that scientists have warned is “incompatible with organized society.” Minimizing future emissions is imperative, but it’s not enough. To meet the Paris Agreement’s commitment to hold the temperature rise “well below” 2°C, humankind must also “go negative.” That is, we must extract the CO2 that’s already in the atmosphere and store it where it can no longer trap heat, notably in the earth’s trees and soil. And that means growing more trees, not cutting them down.

….

This is very bad news, for two reasons. First, until now, the capacity of forests to absorb carbon dioxide via photosynthesis has been a crucial buffer against greenhouse-gas emissions: The forests’ absorption of CO2 has limited the global temperature rise to considerably less than it would otherwise be. Second, forests must absorb even more carbon going forward if humankind is to contain that temperature rise to a survivable amount. Current trends put the earth on a trajectory to an increase of 3.5 degrees Celsius, an amount that scientists have warned is “incompatible with organized society.” Minimizing future emissions is imperative, but it’s not enough. To meet the Paris Agreement’s commitment to hold the temperature rise “well below” 2°C, humankind must also “go negative.” That is, we must extract the CO2 that’s already in the atmosphere and store it where it can no longer trap heat, notably in the earth’s trees and soil. And that means growing more trees, not cutting them down.

“This is really very serious,” says Carlos Nobre, Brazil’s leading climatologist, in an interview at his home in a tree-lined suburb outside São Paulo. Nobre has the tired expression of someone who’s been ringing the alarm bell for too long while society looks away. He says the world’s forests have been absorbing roughly 30 percent of the CO2 emissions generated by human activities. But Nobre’s research, conducted with Thomas Lovejoy of George Mason University, has found that deforestation, combined with rising temperatures and the droughts and fires they encourage, is taking a heavy toll.

“We’re dangerously approaching a point where the convergence of all these drivers might reach irreversibility,” Nobre says. Cross that threshold, and much of the Amazon rain forest will begin to die. The Amazon could reach that tipping point if 20 to 25 percent of its original forest cover is destroyed, Nobre estimates. In that case, more than half the Amazon would transition from rain forest to savannah, releasing massive amounts of CO2 into the atmosphere as the trees die and burn. Such a “dieback” is one of the scenarios that could trigger runaway global warming, according to the “hothouse Earth” study published by the Potsdam Climate Impacts Institute in August.

…(read more).

And view Science article:


http://science.sciencemag.org/content/358/6360/230

Abstract

The carbon balance of tropical ecosystems remains uncertain, with top-down atmospheric studies suggesting an overall sink and bottom-up ecological approaches indicating a modest net source. Here we use 12 years (2003 to 2014) of MODIS pantropical satellite data to quantify net annual changes in the aboveground carbon density of tropical woody live vegetation, providing direct, measurement-based evidence that the world’s tropical forests are a net carbon source of 425.2 ± 92.0 teragrams of carbon per year (Tg C year–1). This net release of carbon consists of losses of 861.7 ± 80.2 Tg C year–1 and gains of 436.5 ± 31.0 Tg C year–1. Gains result from forest growth; losses result from deforestation and from reductions in carbon density within standing forests (degradation or disturbance), with the latter accounting for 68.9% of overall losses.

http://science.sciencemag.org/content/358/6360/230
http://science.sciencemag.org/content/suppl/2017/09/27/science.aam5962.DC1?_ga=2.137720884.56920385.1537901200-1334303521.1534484767

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