Elevated rates of gold mining in the Amazon revealed through high-resolution monitoring

Abstract

Gold mining has rapidly increased in western Amazonia, but the rates and ecological impacts of mining remain poorly known and potentially underestimated. We combined field surveys, airborne mapping, and high-resolution satellite imaging to assess road- and river-based gold mining in the Madre de Dios region of the Peruvian Amazon from 1999 to 2012. In this period, the geographic extent of gold mining increased 400%. The average annual rate of forest loss as a result of gold mining tripled in 2008 following the global economic recession, closely associated with increased gold prices. Small clandestine operations now comprise more than half of all gold mining activities throughout the region. These rates of gold mining are far higher than previous estimates that were based on traditional satellite mapping techniques. Our results prove that gold mining is growing more rapidly than previously thought, and that high-resolution monitoring approaches are required to accurately quantify human impacts on tropical forests.

Keywords: CLASlite; Carnegie Airborne Observatory; Peru; deforestation; forest degradation.

Fig. 1.

(A and B) Typical examples of the interior conditions of the large Guacamayo and Huepetuhe mines. (C) Examples of small-scale mining on and set back from the edge of the Madre de Dios River. In all cases, mines are dominated by extensive, intermixed areas of bare soil and standing pools of water resulting from the mining process.

Fig. 2.

The regional extent and occurrence of small and large mines throughout the southern Madre de Dios region. Note that many mines are closely situated through time, and thus the color chart may not show the year of every mining event. See Figs. S1–S3 for detail. Location key: (i) Huepetuhe, (ii) Delta-1, (iii) Guacamayo. All other unlabeled mines are in the “small mine” category as described throughout the article.

Fig. 3.

(A) Confirmed and suspected deforestation caused directly by gold mining in the southern Madre de Dios region from 1999 to 2012. (B) Contribution of the three large mines compared with small mines from 1999 to 2012. (C) Relative contribution of large and small mines to the total regional mining footprint over time.

Fig. 4.

New deforestation driven by small and large gold mining operations in the years 2008–2012, following the global financial recession and the rapid increase in gold prices.