|Deforestation in the Mato Grasso state of Brazil. Pedro Biondi/Abr/Wikimedia Commons.
Protecting Peru’s rich forestland would be more economically viable if its carbon could be considered as an asset in global markets, such as the one proposed by the United Nations Collaborative Programme on Reducing Emissions from Deforestation and Forest Degradation in Developing Countries, or UN-REDD. But to be in a position to do this, it’s important to be able to quantify this carbon with high accuracy and spatial resolution.
So scientists at Stanford’s Carnegie Institution for Science, together with the government of Peru, set out on an ambitious project—to map the country’s “carbon geography,” or how much carbon is bound up in aboveground vegetation. And that’s not easy, especially in a country with such diverse landscapes as Peru’s. Satellites can “see” surface vegetation, but scientists haven’t yet been able to translate that data into carbon units. And direct field measurements to quantify carbon stored in vegetation, which involves tromping through forests and measuring trees by hand, are far too laborious to carry out at high resolution on a country-wide scale. Recently, however, remote sensing methods have made it much easier to get a good ballpark estimate from the sky.
To map Peru’s carbon, Stanford scientists led by Greg Asner surveyed large swaths of the country with a plane called the Carnegie Airborne Observatory. It’s outfitted with lots of instruments, including one that carries out a remote sensing technique called light detection and ranging, or LiDAR. About 500,000 times per second, this instrument zaps laser pulses of near-infrared light onto the land surface. Some of this light bounces off each layer of vegetation, such as a forest canopy, and some of it passes through to hit the next layers down. By capturing the patterns of light that bounce off all these layers, the scientists can reconstruct a three-dimensional map of the vegetation. Then they calibrate these data with field estimates of carbon bound up in different types of vegetation to generate a map at one-hectare resolution.
|The Carnegie Airborne Observatory. Credit: The High-Resolution Carbon Geography of Peru.
|Carnegie and Peruvian researchers quantified the carbon stocks throughout the entire country of Peru, shown here. Red is highest carbon, dark blue is lowest. Credit: Greg Asner.
Of course, right now, having an embarrassment of carbon doesn’t pay the bills for Peruvians. “How can we save what we can’t don’t understand?” asks Greg Asner, the Stanford scientist who led the research, in a TED talk. The team’s high-resolution map gets us one step closer to that understanding. You can read the full report here.
About Deirdre Lockwood
Chicago Tribune, Nature, Science and Chemical & Engineering News. She's crossed the Pacific eight times on a container ship to study how the ocean absorbs atmospheric carbon dioxide and earned her PhD in oceanography at the University of Washington. She's also blogged about her experiences doing fieldwork on the Mekong River in Thailand, Laos and Cambodia, and spent a year in Iceland as a Fulbright fellow. She's currently a contributing editor at Chemical & Engineering News and curator of the magazine’s archival Tumblr blog, The Watch Glass.