Scientists say the rapid melting of the Quelccaya ice cap, the world’s largest tropical ice sheet, is the latest sign of global warming. (RT @350: 1,600 years of glacial ice, gone in just 25 years.
he evidence comes from a remarkable find at the margins of theQuelccaya ice cap in Peru, the world’s largest tropical ice sheet. Rapid melting there in the modern era is uncovering plants that were locked in a deep freeze when the glacier advanced many thousands of years ago.
Dating of those plants, using a radioactive form of carbon in the plant tissues that decays at a known rate, has given scientists an unusually precise method of determining the history of the ice sheet’s margins.
In the new research, a thousand feet of additional melting has exposed plants that laboratory analysis shows to be about 6,300 years old. The simplest interpretation, Dr. Thompson said, is that ice that accumulated over approximately 1,600 years melted back in no more than 25 years.