Thursday, November 21, 2013

NASA-USGS Landsat data yield best view to date of global forest losses, gains

NASA: The ravages of deforestation, wildfires, windstorms and insects on global forests during this century are revealed in unprecedented detail in a new study based on data from the NASA-U.S. Geological Survey Landsat 7 satellite.

The maps resulting from the study are the first to document forest loss and gain using a consistent method around the globe, at high resolution. They allow scientists to compare forest changes in different countries and monitor annual deforestation. With each pixel in a Landsat image showing an area about the size of a baseball diamond, researchers see enough detail to tell local, regional and global stories.

“Now, we have 12 years of annual forest loss over the globe,” said Matthew Hansen, whose team at the University of Maryland in College Park, Md., led the new study.

Hansen and colleagues analyzed 143 billion pixels in 654,000 Landsat images to compile maps of forest loss and gain between 2000 and 2012. During that period, 888,000 square miles (2.3 million square kilometers) of forest were lost, and 309,000 square miles (800,000 square kilometers) regrew.

...During the study period, Brazil cut its deforestation rate from approximately 15,400 square miles (40,000 square kilometers) per year to approximately 7,700 square miles (20,000 square kilometers) per year. "That's the result of a concerted policy effort to reduce deforestation, and it sets a standard for the rest of the world," Hansen said.

The team found that the deforestation rate in other countries increased.  Indonesia's deforestation rate doubled in the study period, from approximately 3,900 square miles (10,000 square kilometers) per year in 2000-2003 to more than 7,700 square miles (20,000 square kilometers) in 2011-2012....

The border between Malaysia and Indonesia on the island of Borneo stands out in the Landsat-based map of forest disturbance. Red pixels represent forest loss between 2000 and 2012. Image Credit: NASA Goddard, based on data from Hansen et al., 2013.

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