The study, published January 25, 2019, 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.
Researchers from the University of Colorado, led by Simon Pendleton, lead author and a doctoral researcher in CU Boulder's Institute of Arctic and Alpine Research (INSTAAR), have been studying the retreat of glaciers on Baffin Island for over 12 years. Pendleton has witnessed the changes over the years first hand.
“We know there is a dramatic change occurring and will continue to occur, but I don’t know that we were expecting to find evidence that we’re now seeing landscapes and temperatures similar to that of the last interglacial period,” Pendleton said, reports ZME Science.
Baffin Island is the world's fifth largest island and lies within the Canadian Arctic, west of Greenland. The region is one of high plateaus, covered in ice caps and deeply incised fjords. The thin ice caps on the plateaus have basically acted as natural cold storage for the ancient moss and lichens - keeping them in their original growth position for millennia.
Because Baffin Island is within the Arctic Circle, the region is experiencing warming at a rate two to three times the global average, and according to Pendleton, the glaciers and ice caps are going to react to the warming at an accelerated rate.
"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, like those of the past century"
Collecting plants and rock samples
The research team collected a total of 124 plant, moss, and rock samples from 30 sites around the island, all from within a meter from the edge of the ice cap, the most vulnerable part of the melting ice cap. The team also collected quartz samples from the sites in order to further establish the age and ice cover.
All the samples were processed and radiocarbon dated back in labs at the Institute of Arctic and Alpine Research (INSTAAR) at CU Boulder and the University of California Irvine. Incredibly, the plants from all 30 sites have likely been continuously covered by ice for at least the past 40,000 years, according to Science Daily.
"Unlike biology, which has spent the past three billion years developing schemes to avoid being impacted by climate change, glaciers have no strategy for survival," said Gifford Miller, senior author of the research and a professor of geological sciences at CU Boulder.
"They're well behaved, responding directly to summer temperature. If summers warm, they immediately recede; if summers cool, they advance. This makes them one of the most reliable proxies for changes in summer temperature."
Significance of findings
When researchers compare temperature data reconstructed from Baffin and Greenland ice cores with their findings, it suggests that the temperatures we are experiencing today represent the warmest century for the region in 115,000 years.
While it may be quite an achievement for today's scientists to walk on newly exposed ground that has been covered in ice for 40,000 years, they are doing so at the expense of a warming world. “To be able to see it and walk on the ice cap and understand we’re in a time that’s exposing landscapes that haven’t seen sunlight in possibly 120,000 years, that has a profound effect,” Pendleton said.
Additional co-authors of the study include Scott Lehman, Sarah Crump and Robert Anderson of CU Boulder; Nathaniel Lifton of Purdue University; and John Southon of the University of California Irvine. The National Science Foundation provided funding for the research.
