LIMA, Peru — Scientists have long known that halting climate change will be impossible without stopping the destruction of the world’s forests.

Along with providing the planet with oxygen, trees also store huge amounts of carbon. When they go up in flames, it enters the atmosphere as carbon dioxide, the main gas causing global warming.

Currently, around 15 percent of global greenhouse gas emissions come from deforestation, above all in the tropics where forests are most lush.

Yet quantifying the precise amount of carbon in the world’s jungles has been unachievable — until now.

A new study reveals that Peru’s vegetation warehouses 6.9 billion metric tons (7.6 billion tons) of carbon, almost all of it in the Amazon.

It’s the first time that an accurate inventory of forest carbon has been published for any of the world’s major jungle nations.

To put that figure in context, the United States’ entire 2012 greenhouse gas emissions from cars and other forms of transportation were 1.74 billion metric tons (page 5).

Published July 31, the $1.2-million study was carried out by a team led by Greg Asner, a researcher at the Carnegie Institution for Science in Washington, DC.

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Using state-of-the-art laser technology Asner developed to penetrate the forest canopy, the team spent more than three months flying over the Peruvian Amazon — an area twice the size of California.

Gauging forest carbon by the traditional method — on foot, measuring trunk diameters by hand — would have taken so long it would have been impossible.

It also would have been far less precise and would have cost vastly more than the 1-cent-per-hectare (2.47 acres) rate for the Carnegie team.

The map produced by the research even shows carbon density hectare by hectare across the country, with red representing the highest concentrations and blue the least. In the densest parts of the jungle, the trees stored a massive 168 metric tons of carbon per hectare.

Peru has the world’s fourth largest tropical rain forest, with only Brazil, Congo and Indonesia having more. But it may be about to move into third place thanks to heavy logging on the Indonesian island of Sumatra, Asner says.

The Peruvian Amazon remains relatively intact. But pressures are building, including logging, illegal mining, agriculture, poaching and climate change itself, and starting to ail the jungle.

The government recently even curbed environmental safeguards in a controversial attempt to boost economic growth.

“Peru is on the precipice right now between rapid destruction of its forests or sustainable development,” Asner said.

He now hopes his technology will be used to build accurate carbon inventories in other nations with large jungles — and help develop government policies that laser in on the causes of deforestation.

As for Peru, its own forest policies are likely to come increasingly under the international spotlight as the capital, Lima, hosts the next round of United Nations climate talks in December.

Also from the report, here’s a sample of Peru’s ecosystems mapped by the Carnegie Airborne Observatory.

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