It has been nearly 120,000 years since Earth was this warm, and 40,000 years since some ice-swathed Arctic lands have seen the sun.
This is one conclusion of a study published recently in the journal Nature Communications, in which researchers carbon-dated plants collected at the edges of 30 ice caps on Baffin Island, in the Canadian Inuit territory of Nunavut.
“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 at the Institute of Arctic and Alpine Research (Instaar), in a statement.
The study was conducted at the University of Colorado at Boulder, the United States, where Instaar is located, and in conjunction with the University of California at Irvine, as well as Purdue University, Indiana.
Baffin is the world’s fifth-largest island, lying west of Greenland, which has also been shown to be melting precipitously. The population is predominantly Inuit.
“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 in the statement.
“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.”
Under this logic, researchers at CU Boulder and partners analysed 48 plant samples from numerous elevations and exposures and found that they had most likely been continuously covered by ice for 40 millennia.
Glaciers are a direct indicator of temperature, pointed out study senior author Gifford Miller, a geological sciences professor at CU Boulder. Purdue University’s Nathaniel Lifton also contributed to the research, which was funded by the National Science Foundation.
“If summers warm, they immediately recede; if summers cool, they advance,” Miller noted in the statement. “This makes them one of the most reliable proxies for changes in summer temperature.”
Canada hosts about 30% of the glaciers in the world, according to Arctic Today, a news service. After Antarctica and Greenland, that country’s glaciers are the biggest contributor to sea rise.
A recent survey of 1,773 glaciers across northern Ellesmere Island, also in Nunavut, found that upward of three-quarters of them had lost area from 1999 to 2015, with an overall 6% loss of total ice coverage, Arctic Today reported in July 2018. – Tribune News Service/New York Daily News