Ice sheets react to short cold snaps, study finds
A new study has investigated how fast glaciers melt and grow in response to changes in temperature. It adds to evidence showing ice sheets can react rapidly to cooling or warming, raising concerns that they could do again as the Earth heats.
The results of the Arctic research, led by an associate professor from The University at Buffalo, New York, in America, are being published in the Science journal.
The study tells how glaciers on Baffin Island, Canada, expanded rapidly when a brief cold snap hit around 8,200 years ago.
Co-author of the report, Jason Briner, PhD, a University at Buffalo associate professor of geology, says, "One of the questions scientists have been asking is how long it takes for these huge chunks of ice to respond to a global climate phenomenon.
"People don't know whether glaciers can respond quickly enough to matter to our grandchildren, and we're trying to answer this from a geological perspective, by looking at Earth's history."
"What we're seeing is that these ice sheets are surprisingly sensitive to even short periods of temperature change."
The research suggests that mountain glaciers on Baffin Island and the huge North American ice sheet expanded quickly as the Earth cooled around 8,200 years ago.
The result was surprising as the cold snap was so short and the temperature fell for just a few decades and then returned to previous levels within 150 years.
Lead author Nicolás Young, who worked on the study as part of his PhD at UB and is now a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory, says, "It's not at all amazing that a small local glacier would grow in response to an event like this, but it is incredible that a large ice sheet would do the same."
Ayr Lake, Baffin Island, Canada; Credit: © Credit: Jason Briner
To conduct the research, Dr Briner led a team to Baffin Island to check the landscape for details about the size and activity of glaciers that covered the island during the study period.
Moraines - piles of rocks and debris that glaciers leave as they expand - yielded vital information. By dating these and other geological features, the researchers discovered that glaciers expanded rapidly on Baffin Island during the short-lived cold snap.
They also discovered the island's glaciers seem to have been larger in the brief period of cooling than in the Younger Dryas period, a more severe period of cooling that started around 13,000 years ago and lasted for more than a millennium. This suggests unexpected factors may influence the way a glacier responds to climate change.
While Baffin Island cooling may have been worse during the Younger Dryas, summer temperatures may have fallen more during the changes 8,200 years ago.
The colder summers could have accelerated the glaciers' quick advance, lowering the length of time ice melted in summer.
Similar detailed studies are vital to develop accurate models that predict how climate change will affect glaciers around the world, Prof. Briner says.
A video outlining the findings:
Co-authors were Dylan H. Rood, from the Scottish Universities Environmental Research Centre and the University of California, Santa Barbara; and Robert C. Finkel from UC Berkeley.
The research was financed by the National Science Foundation.
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