Extent of Peruvian Amazon lost to illegal goldmines mapped for first time

Dan Collyns in the Guardian (UK): The area affected by illegal gold mining in Peru's south-eastern Amazon region increased by 400% from 1999 to 2012, according to researchers using state-of-the-art mapping technology.

Using airborne mapping and high-satellite monitoring, researchers led by the Carnegie Institution for Science also showed that the rate of forest loss in Madre de Dios has tripled since the 2008 global economic crisis, when the international price of gold began to rise to new highs.

Until this study, thousands of small, clandestine mines that have boomed since the economic crisis went unmonitored, according to the research team, which was led by Carnegie's Greg Asner and worked with Peru's environment ministry.

Crucial technological differences, such as the use of the Carnegie Landsat Analysis System-lite (CLASlite), meant the team was able to map both large and small mining operations.

"The gold miners are working in thousands of small groups, so it takes our high resolution techniques to map their activities," said Asner, who developed the Carnegie Airborne Observatory (CAO), technology that uses algorithms to detect changes to the forest in areas as small as 10 square metres (about 100 square feet), allowing scientists to find small-scale disturbances that cannot be detected by traditional satellite methods....

This CLASlite map shows the areas along the Madre De Dios river damaged by small, clandestine gold miners between 1999 and 2012. Photograph: CLASlite Team