Global Warming

Record Melt Occurring in Greenland Glaciers

Greenland’s glaciers are retreating under the influence of climate change at least twice as fast as any other time in the past 9,500 years, according to new research.

Scientists from Columbia University’s Earth Institute made the discovery after examining sediment cores from the bottom of a glacier-fed lake in southeastern Greenland.

They then compared the findings to analyses of similar cores from Iceland and Canada’s Baffin Island, and with recent satellite observations.

They found that before the 20th century, the fastest rate of glacier retreat occurred about 8,500 years ago, when the Earth’s position relative to the sun resulted in more summer sunlight warming the Arctic.

Despite less direct summer sunlight in recent years, Greenland’s glaciers have melted at an unprecedented rate because of warming brought on by higher greenhouse gas concentrations.

“If we compare the rate that these glaciers have retreated in the last hundred years to the rate that they retreated when they disappeared between 8,000 and 7,000 years ago, we see the rate of retreat in the last 100 years was about twice what it was under this naturally forced disappearance,” said study co-author William D’Andrea.

The study also provided new evidence for just how sensitive glaciers are to temperature, showing that they responded to past abrupt cooling and warming periods, some of which might have lasted only decades.

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