Andean Ice That Solidified Over 1,600 Years Melted in 25

The Quelccaya ice cap sits 18,000 feet above sea level, high in the Peruvian Andes, where it earns the title of world's largest tropical ice sheet. But its size is diminishing, and a team of glaciologists have come to a dramatic conclusion about the recent melting. In a paper released yesterday, they assert that ice that took 1,600 years to form melted in, at most, just 25. The New York Times explains how they arrived at the finding.

The group previously analyzed plants that had been frozen by the glacier, then revealed in recent melting; they were judged to be 4,700 years old. But the ice has melted even more, revealing plants determined to be 6,300 years old; the team concluded it took 25 years to undo what had formed over 1,600 years. "If any time in the last 6,000 years these plants had been exposed for any five-year period, they would have decayed," says the team leader. "That tells us the ice cap had to be there 6,000 years ago." (More Andes stories.)