1600 Years of Ice Melts in 25 Years

Qori Kalis Glacier in Peru. Left: July 1978. Right: July 2004 - Source: NASA

Qori Kalis Glacier in Peru. Left: July 1978. Right: July 2004 – Source: NASA

Scientists recently reported that glacial ice in the Peruvian Andes that took over 1,600 years to form has melted in only 25 years. They were able to record this astonishing record of accelerated climate change through the process of carbon dating. So how exactly did they do that?

The melting ice exposed plants previously frozen in place when the Quelccaya ice cap grew thousands of years ago. Scientists were then able to take these plants and carbon date them. Dating of those plants 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 of that finding is that ice that accumulated over approximately 1,600 years melted back in no more than 25 years.

According to Dr. Lonnie Thompson, a glaciologist whose team worked on the glacier for decades said that, “If any time in the last 6,000 years these plants had been exposed for any five-year period, they would have decayed. That tells us the ice cap had to be there 6,000 years ago.”

Global warming, which scientists say is being caused primarily by the human release of greenhouse gases, is having its largest effects at high latitudes and high altitudes. Sitting at high elevation in the tropics, the Quelccaya ice cap appears to be extremely sensitive to the temperature changes, several scientists said.

The melting ice in the Andes is especially concerning for people living in the region who get their water from the glacier. Once the ice is gone, 50 percent and Lima and La Paz’s residents will have to look elsewhere for their water supply.

Source: NY Times

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