Satellite provides new insights into global forest losses

Satellites have provided the clearest view yet of the ravages of deforestation, wildfires, windstorms and insects on global forests, NASA scientists say. Maps created from data from the NASA-U.S. Geological Survey Landsat 7 satellite are the first to document forest loss and gain using a consistent method around the globe, at high resolution, they said. The researchers analyzed 143 billion pixels in 654,000 Landsat images to compile maps of forest loss and gain from 2000 to 2012, with each pixel showing an area about the size of a baseball diamond, the maps provide enough detail to demonstrate local, regional and global impacts of forests, NASA reported Friday. "Now, we have 12 years of annual forest loss over the globe," study leader Matthew Hansen at the University of Maryland said. During those years more than 888,000 square miles of forest were lost, and 309,000 square miles regrew, the researchers said. Before this study, they said, country-to-country comparisons of forestry data were not possible at this level of accuracy, as many countries defined forests differently. "When you put together datasets that employ different methods and definitions, it's hard to synthesize," Hansen said. "But with Landsat, as a polar-orbiting instrument that takes the same quality pictures everywhere, we can apply the same algorithm to forests in the Amazon, in the Congo, in Indonesia, and so on. It's a huge improvement in our global monitoring capabilities."