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January 25th, 2019

A landscape unseen in over 40,000 years

Researchers walk the edge of a Baffin Island ice cap, looking for dead plants recently melted out of the ice that had preserved them for thousands of years.

Glacial retreat in the Canadian Arctic has uncovered landscapes that haven’t been ice-free in more than 40,000 years and the region may be experiencing its warmest century in 115,000 years, new CU Boulder research finds.

The study, published today in the journal Nature Communications, uses radiocarbon dating to determine the ages of plants collected at the edges of 30 ice caps on Baffin Island, west of Greenland. The island has experienced significant summertime warming in recent decades.

“The Arctic is currently warming two to three times faster than the rest of the globe, so naturally, glaciers and ice caps are going to react faster,” said Simon Pendleton, lead author and a doctoral researcher in CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR). 

Baffin is the world’s fifth largest island, dominated by deeply incised fjords separated by high-elevation, low-relief plateaus. The thin, cold plateau ice acts as a kind of natural cold storage, preserving ancient moss and lichens in their original growth position for millennia.

A recently-exposed clump of dead moss at the margin of an ice cap.

“We travel to the retreating ice margins, sample newly exposed plants preserved on these ancient landscapes and carbon date the plants to get a sense of when the ice last advanced over that location,” Pendleton said. “Because dead plants are efficiently removed from the landscape, the radiocarbon age of rooted plants define the last time summers were as warm, on average, as those of the past century.”

Once the samples were processed and radiocarbon dated back in labs at INSTAAR at CU Boulder and the University of California Irvine, the researchers found that these ancient plants at all 30 ice caps have likely been continuously covered by ice for at least the past 40,000 years.

Read the rest of the story at CU Boulder Today.

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