Global warming: How fast will the ice melt?

Research finds that ice sheets can be very sensitive to short-term temperature variations. Photo by Bob Berwyn.

Study shows some glaciers and ice fields can respond quickly and dramatically even to short-lived climate changes

By Summit Voice

SUMMIT COUNTY — It’s pretty clear that glaciers and ice fields have been melting the past few decades under relentless global warming. But scientists aren’t sure exactly how fast the melting will proceed, whether it will speed up, or perhaps stabilize at some point.

A new study looking back at historic changes in response to climate variations may help answer some of those questions. The research shows that glaciers on Canada’s Baffin Island expanded rapidly during a brief cold snap about 8,200 years ago, suggesting that changes can be sudden and drastic.

“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,” said study co-author Jason Briner, PhD, a University at Buffalo associate professor of geology. “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,” he added, describing the research team’s findings on Baffin Island.

The results were surprising because the cold snap was extremely short-lived: The temperature fell for only a few decades, and then returned to previous levels within 150 years or so.

“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,” said lead author Nicolás Young, who is now a postdoctoral researcher at Columbia University’s Lamont-Doherty Earth Observatory.

The team reached its conclusions after examining and dating glacial landscapes on Baffin Island. Moraines — piles of rocks and debris that glaciers deposit while expanding — provided valuable information, showing that glaciers expanded rapidly on Baffin Island about 8,200 years ago, a period coinciding with a short-lived cold snap.

The researchers also found that Baffin Island’s glaciers appeared to have been larger during this brief period of cooling than during the Younger Dryas period, a much more severe episode of cooling that began about 13,000 years ago and lasted more than a millennium.

This counterintuitive finding suggests that unexpected factors may govern a glacier’s response to climate change.

With regard to Baffin Island, the study’s authors say that while overall cooling may have been more intense during the Younger Dryas, summer temperatures may have actually decreased more during the shift 8,200 years ago. These colder summers could have fueled the glaciers’ rapid advance, decreasing the length of time that ice melted during the summer.

Detailed analyses of this kind will be critical to developing accurate models for predicting how future climate change will affect glaciers around the world, Briner said.


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