Counting carbon in the Amazon: the results are in - September 06, 2010

Nature.com. Nearly a year after Nature featured Greg Asner's latest efforts to map forest carbon in the Peruvian Amazon, the official results are in. The researchers calculated 395 million tonnes of carbon stored in more than 4.3 million hectares of forest in the Madre de Dios region of southeast Peru, while identifying some interesting long-term trends on deforestation and consequent greenhouse gas emissions (Reuters, New Scientist).



Published Monday in the Proceedings of the National Academy of Sciences, the study represents the first full-scale deployment of an integrated system developed by Asner, a remote sensing expert in the Carnegie Institution of Science's Global Ecology Program, for assessing and monitoring carbon locked up in tropical forests. His goal is to provide a user-friendly system for accurately tracking carbon in support of a global warming policies that seek to reduce carbon emissions from deforestation, and as such he has already licensed the technology - free of charge - to Peru and other Latin American countries.

Combining an analysis of ground plots, aircraft-based laser measurements and satellite data, the researchers provided the most detailed analysis yet of a large swath of tropical rainforest. Their figures came in a third lower than a 587-million-tonne baseline estimate using methods from the Intergovernmental Panel on Climate Change (although to be fair, the IPCC methods in question are intended to provide a preliminary estimate until such time as a more-detailed analysis can be conducted).

Asner's team then analyzed satellite data between 1999 and 2009 in order to estimate how much carbon was lost to mining, selective logging and deforestation, driven in large part by the paving of the Interoceanic Highway.

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Roughly 1.1 percent of the standing carbon was released into the atmosphere, they found, which equates to roughly 630,000 metric tonnes per year. Forest degradation was responsible for a 47-percent increase over carbon emissions from full-scale deforestation, while forest regrowth offset cumulative emissions by 18 percent (for a global view, check here).

The study has some intriguing ecological implications as well. Amazon researchers are always pointing out that the forest is much more complex and diverse than people tend to believe, with various soil types producing a patchwork effect spanning the many hills and dales that make up this vast region. This study was no exception. Asner's crew analyzed the local geology and found that vegetation growing on young, fertile soils contained 25 percent more carbon than forests growing on older geologic formations.

The Peruvian study was designed as a full-scale test case. Asner deployed the methods in the field while training Peruvian government officials to move forward on their own. He presented some initial results during the climate talks last year in Copenhagen, making the case that remote-sensing technologies are ready for prime time and can be quickly deployed by countries that have little or no experience in this arena. And to help spread the word, he partnered with Google on a forest-monitoring tool that could make the satellite component available to all.

In Asner's view, these technologies no longer belong in the realm of science. During our time in Peru, he told me that his goal was to put himself - and any colleagues working on this particular issue - "out of business."
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