Research in the Canadian Arctic led by the University of Colorado shows that glacial retreat has revealed landscapes that have not been free of ice for at least 40,000 years, and that the region might be experiencing its warmest century in 120,000 years.
Simon Pendleton, a doctoral researcher at the University of Colorado‘s Institute of Arctic and Alpine Research, is the published Friday in the journal Nature Communications.
“Having put some time in up there, and observed some of the changes going on, on the ground it is impressive, the rate and the magnitude at which change is occurring in the Arctic,” said Pendleton, who took about five trips to the Baffin Island for field research associated with the study.
“And there are implications for the ecosystem change, the sea level rise, ocean circulation and climate change.”
Pendleton said the Arctic is currently warming three times faster than the rest of the globe, hastening the retreat of the glaciers.
“We have not one, not two, but 30 (data collection) sites across a wide region of Baffin Island, which gives us more confidence that we are seeing icescapes being exposed, landscapes exposed, that have been covered for the last 120,000 years,” Pendleton said.
Pendleton and his colleagues traveled to retreating ice margins across Baffin Island, sampling newly exposed plants from varying elevations and exposures that had been preserved by advancing ice, then under radiocarbon dating to establish when ice last advanced over that specific site.
They also sampled quartz from each site in order to further establish the age and ice cover history of the landscape.
Processing the samples, and radiocarbon dating them in labs at the Institute of Arctic and Alpine Research and the University of California Irvine, showed that the ancient plants at all 30 ice caps have likely been continuously covered by ice for at least the past 40,000 years.
Or, very likely, longer.
Pendleton said radiocarbon dating‘s effectiveness only goes back about 40,000 years; hence, his findings that ice coverage of the region under study goes back “at least” 40,000 years. To determine how much further it extends beyond that, scientists turned to a long-term temperature record compiled at the Greenland ice sheet, which shows that the most recent warm period there was about 120,000 years ago.
“Our data doesn‘t specifically say it was 120,000 years. But by using what our data says about continuous cover for the last 40,000 years, and using the temperature records, we can speculate that they have been continuously ice-covered for the last 120,000 years.”
Additional co-authors on the study include Scott Lehman, Sarah Crump and Robert Anderson of CU, Nathaniel Lifton of Purdue University and John Southon of UC Irvine. Funding for the research was provided by the National Science Foundation.
The scientists calculate that Baffin Island could be ice-free within the next few centuries.