The three-dimensional map could help clear the way for an international agreement to curb deforestation and forest degradation, which account for up to one-fifth of all greenhouse gases released by human activities, according to United Nations estimates.
Climate negotiators have been working on an international deal to slow global warming, including a U.N. proposal known as REDD, short for Reducing Emissions from Deforestation and forest Degradation.
This proposal has been hampered by the difficulty of figuring out how much carbon forests keep out of the atmosphere — because plants take in carbon dioxide and use it in the process of photosynthesis — and how much deforestation contributes to the greenhouse effect by releasing this stored carbon into the air.
The details in the new map could help change that, said Greg Asner of the Carnegie Institution for Science, lead author of a study that produced the map. The study is being published in Proceedings of the National Academy of Sciences.
\”What we\’re showing here for the first time is an ability to not only map the carbon … that is in the forest, but also use a technique that allows us to estimate the emissions,\” Asner said in a telephone interview from Hawaii, where he is doing field work.
In terms of an international climate treaty, that\’s the big one
SATELLITES AND LASERS
To create the map, Asner and his colleagues used satellite images that looked at vegetation and where it had been disturbed, and then used data gathered by a flying laboratory plane equipped with laser technology to produce a three-dimensional map of trees and other vegetation.
Because these 3-D images showed the specific structure of the plants, researchers were able to pair this information with ground-based data to calculate how much carbon they contained, Asner said.
Using historical information on deforestation and forest degradation, the scientists were also able to calculate carbon emissions from 1999-2000 for this part of Peru, the Madre de Dios region.
Deforestation is the almost total destruction of forest. In the Switzerland-size area of the study, the forest is usually cleared for cattle ranching, agriculture or mining.
Forest degradation, Asner said, is the over-utilization of forest \”to the point where it\’s falling apart,\” often the result of selective logging and low-intensity fires.
Another advantage of the map is that it shows the effects of degradation, which have until now been hard to quantify.
\”If you don\’t include the degradation you\’re going to miss a lot of the emissions,\” he said. \”They contribute 50 percent more carbon to the atmosphere in this region … than just deforestation alone.\”