In 2011, scientists from North Carolina, France, and Peru saw that deforestation in a portion of the Amazon rainforest was proceeding at an unusual pace in an unexpected place. Images from the Landsat 5 satellite clearly showed that deforestation had increased six-fold over a six-year period in the remote Madre de Dios region of Peru, near the Bolivian border. No one knew why.
Compelled by the images, investigators visited the forest and found serious mercury poisoning affecting both the people and the wildlife. Driven by soaring gold prices, miners were clearing trees for gold. The result was not only further deforestation, but mercury pollution from the mining process.
The images above were taken on October 15, 2003 (left), and September 3, 2011, by the Thematic Mapper on the Landsat 5 satellite. Landsat actually did not see the mercury pollution; it saw deforestation where it should not have been happening.
With the price of gold skyrocketing (360 percent in 10 years from 2001 to 2011), unlicensed miners began pouring into Peru’s Madre de Dios. They cleared 12,500 acres from the forest between 2003–2009. Landsat images showed local deforestation increasing at a rate of 26 percent per year.
While the deforestation itself was not great enough to pose much of a threat to the forest, the mercury was. Miners use mercury to extract gold from rocks. It vaporizes during the process and becomes airborne, eventually poisoning water supplies. Mercury was getting into the fish, and the people were eating the fish. They were also drinking the water. Tests of local residents showed that the closer they were to the mines, the more mercury in their bodies.
Landsat compelled the scientists to investigate. Without America’s longest running Earth-imaging satellite program, it is unlikely scientists would have seen the pollution or the deforestation at Madre de Dios for years, and the health of local residents would have been seriously affected. Landsat may have saved lives.
For more information, read Landsat Looks and Sees: Forty Years of Observations Reveal a Changing Planet and Society.