Mapping Carbon in the Amazon

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The Amazon rainforest has long been considered by scientists as critical to the health of the planet. Deemed the lungs of the Earth, the Amazon helps to keep the global carbon budget in balance by taking in large amounts of carbon dioxide. However, the rainforests of South America are constantly under threat from human activities including oil and gas exploration, slash-and-burn agriculture, and logging. A new mapping project could help protect the vulnerable forests by revealing how they store carbon.

The rainforests contribute to the health of the planet in critical ways. First of all, the forests absorb about 25 percent of carbon dioxide that comes from both human and natural sources. The Amazon rainforests also store carbon, and scientists estimate that current levels are at 120 billion tons. To help protect the forests, scientists needed a way to map their carbon stores in order to get a better idea of how the areas are changing and where the most dense carbon areas are located.

In order to produce the most detailed carbon maps, they turned to remote sensing, specifically satellite imagery and LiDAR. Staff scientist Greg Asner and his team at the Carnage Institute for Science surveyed rainforests in Peru and measured areas of the forest that ranged in carbon content from zero near the coast to 150 metric tons per hectare, or 2.47 acres, deeper in the rainforest. They were able to find those areas that contained the highest concentrations of carbon as well as those at the highest risk for development.

The geography of aboveground carbon density (ACD) throughout Perú, derived at a 1-ha resolution with uncertainty reported for each hectare. Source: Asner et al, 2014.

The geography of aboveground carbon density (ACD) throughout Perú, derived at a 1-ha resolution with uncertainty reported for each hectare. Source: Asner et al, 2014.

The implications of their findings are sobering, however. The team discovered that an astonishing 0.8 billion metric tons of carbon are at risk for being released into the atmosphere due to deforestation. In addition, if more of Peru’s forests go unprotected, a third of the carbon stored in trees and plants would be released into the atmosphere. This would not only prevent future carbon from being stored there but help fuel climate change as well.


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The threat to Peru’s rainforests and the Amazon overall are particularly striking. More than 19.6 million hectares, or 75,676 square miles, in Peru have already been allowed to be logged and developed for oil and gas. This is an area about the size of Nebraska. There are other studies that suggest that up to 65 percent of the biomass in the Amazon could be lost by 2060. This loss could severely impact the forest’s ability to store carbon.

Mapping the Amazon’s stores of carbon could go a long way to helping protect the forests, though. This study is the first one to produce high-resolution images of the carbon stocks of tropical vegetation on a national scale. The resolution and accuracy of these carbon maps are so precise that landowners of individual pieces of property can compare their land to their neighbors in regards to carbon content.

There is also hope that this mapping technique could be used to help scientists determine how use of the land affects rainfall patterns in the Amazon. Recent research has shown that, in the last 14 years, rainfall in the Amazon is declining as much as 25 percent, partly because of the lack of vegetation. These remote sensing mapping techniques could be applied to other parts of the globe as well in order to chart the carbon stores of different forests and help keep the Earth well.

References:

Asner, G.P., D.E. Knapp, R.E. Martin, R. Tupayachi, C.B. Anderson, J. Mascaro, F. Sinca, K.D. Chadwick, M. Higgins, W. Farfan, W. Llactayo, and M.R. Silman. 2014. Targeted carbon conservation at national scales with high-resolution monitoring. Proceedings of the National Academy of Sciences doi:10.1073/pnas.1419550111

“New Amazon Carbon Maps Could Slow Deforestation.” http://www.scientificamerican.com/article/new-amazon-carbon-maps-could-slow-deforestation/