A new study published in Science finds that a critical glacier in the Peruvian Andes has shrunk to its smallest extent nearly since the end of the last Ice Age. Ohio State University glaciologist Lonnie G. Thompson is studying plants that have been recently exposed near Quelccaya Ice Cap, the world's largest tropical ice sheet, located 18,000 feet above sea level (straddling the border of Cuzco and Puno regions). Chemical analysis of plants exposed by melting several years ago showed them to be about 4,700 years old, proving that the ice cap had reached its smallest extent in nearly five millennia. In the new findings, a thousand feet of additional melting has exposed plants that lab analysis shows to be about 6,300 years old. Thompson said this indicates that ice that had accumulated over approximately 1,600 years melted back in no more than 25 years.

Researchers consider the ice cap to be a "Rosetta Stone" of climate change over the past millennia, boasting clues to anomalous weather in 1789 that might have caused food shortages that helped spark the French Revolution. Thompson's team has "archived" samples of the ice in refrigerated storage, lest the glacier disappear entirely. But the dramatic shrinkage of the glaciers has grim implications for the people of the Andean nations. The coastal zone west of the Andes, home to two-thirds of Peru's population and 80% of economic activity, receives just 2% of the country's fresh water. Lima is considering a $500 million project to drill a tunnel through the Andes to bring in water from the Amazon basin to the arid coastal zones. "How much time do we have before 50 percent of Lima's or La Paz's water resources are gone?" researcher Douglas R. Hardy asked the New York Times. (Countercurrents, April 6; The Week, UPI, Daily Mail, April 5; NYT, April 4; Quelccaya Ice Cap blog, CRONUS-Earth Project)

See our last post on the climate crisis in the Andes.