Gold mines across the Peruvian Amazon increased by more than 400% from 1999 to 2012, and are now the main cause of deforestation there.

A team led by Gregory Asner of the Carnegie Institution for Science in Stanford, California, validated the results from satellite data using field sampling and high-resolution aerial surveys. These estimates are twice that of previous studies, and suggest that mining covered fewer than 10,000 hectares in 1999 but had spread beyond 50,000 hectares by September 2012.

The rate of forest loss more than tripled as gold prices rose in 2008, and was driven by small, illegal mining operations that now account for most activity in the region.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1318271110 (2013)