Last remnant of North American ice sheet on track to melt

The Barnes Ice Cap on Baffin Island is set to melt in 300 years because of a warming climate, researchers have found.

The Delaware-sized ice cap in the Canadian Arctic is the last piece of ice sheet that once blanketed much of North America.

Although the ice cap is still 500 meters thick, it’s melting at a rapid pace driven by increased greenhouse gases in the atmosphere that have elevated Arctic temperatures.

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An aerial view of the Barnes Ice Cap on Baffin island in the Canadian Arctic. Under the 'business-as-usual' greenhouse gas emissions scenario, the last remnant of North American ice sheet is set to melt in about 300 years

An aerial view of the Barnes Ice Cap on Baffin island in the Canadian Arctic. Under the ‘business-as-usual’ greenhouse gas emissions scenario, the last remnant of North American ice sheet is set to melt in about 300 years

Under the ‘business-as-usual’ greenhouse gas emissions scenario, the last remnant of North American ice sheet is set to melt in about 300 years.

The authors of the research say that the results provide evidence that the current level of warming is almost unheard of in the past 2.5 million years

The Barnes Ice Cap has only been so small three times in that time, indicated by a study of isotopes created by cosmic rays that were trapped in the rocks around the Barnes Ice Cap.

THE LAURENTIDE ICE SHEET

The Laurentide Ice Sheet once covered millions of square miles of North America

The Laurentide Ice Sheet once covered millions of square miles of North America

The Barnes Ice Cap is part of the Laurentide Ice Sheet that has covered millions of square miles of North America episodically since the start of the Quaternary Period about 2.5 million years ago.

It grew and shrank as Earth went through various climate cycles, and the ice was a mile thick at Chicago 20,000 years ago.

But it started receding 14,000 years ago when Earth slipped out of its last ice age.

It stabilized about 2,000 years until the effects of the recent warming caught up with it.

At its peak, the sheet stretched down to New York, forming the city we know today, from Long Island—created by moraines and outwash from the glacier—to the archipelago of greater New York City, created by rising tides as the ice sheet melted.

Even Central Park is littered with boulders left over from its movement.

Neighborhoods are named for this ancient ice event: Flatbush in Brooklyn is the point where the ice stopped and began to retreat, leaving low-lying neighborhoods like Canarsie and the outwash beaches, like Coney Island.

‘This is the disappearance of a feature from the last glacial age, which would have probably survived without anthropogenic greenhouse gas emissions,’ said Dr Adrien Gilbert, a glaciologist at Simon Fraser University in Canada and lead author of the study published today in Geophysical Research Letters, a journal of the American Geophysical Union.

Although the melting of the Barnes Ice Cap wont have much of an effect on sea-level rise, its end could signal the eventual dissolution of large ice sheets like Greenland and Antarctica, said CU Boulder Professor Gifford Miller, a co-author of the study and the associate director of CU Boulder’s Institute of Arctic and Alpine Research (INSTAAR) who has conducted research on Baffin Island annually for the past fifty years.

‘I think the disappearance of the Barnes Ice Cap would be just a scientific curiosity if it were not so unusual,’ said Professor Miller.

‘One implication derived from our results is that significant parts of the southern Greenland Ice Sheet also may be at risk of melting as the Arctic continues to warm,’ he said.

Sea rise created by a melting Greenland would cause the Antarctic Ice Sheet, whose dimensions are controlled by sea level, to also shrink in size, said Professor Miller.

The Barnes Ice Cap is part of the Laurentide Ice Sheet that has covered millions of square miles of North America episodically since the start of the Quaternary Period about 2.5 million years ago.

Pictured is CU Boulder Professor Gifford Miller - part of the team that has found the Barnes Ice Cap on Baffin Island, the last remnant of the Laurentide Ice Sheet, will vanish in several hundred years because of rising temperatures caused by human activity

Pictured is CU Boulder Professor Gifford Miller – part of the team that has found the Barnes Ice Cap on Baffin Island, the last remnant of the Laurentide Ice Sheet, will vanish in several hundred years because of rising temperatures caused by human activity

It grew and shrank as Earth went through various climate cycles, and the ice was a mile thick at Chicago 20,000 years ago.

But it started receding 14,000 years ago when Earth slipped out of its last ice age.

It stabilized about 2,000 years until the effects of the recent warming caught up with it.

Professor Miller was conducting research on Baffing Island in 2009 when he realized the ice cap had shrunk significantly compared to a few decades earlier, so he collaborated with Dr Adrien Gilbert and Dr Gwenn Flowers from Simon Fraser University to develop a model of how the ice cap might behave in the future.

In this new study, the researchers used their model to estimate when the ice cap would melt under different greenhouse gas scenarios.

But under all future emissions scenarios, the ice cap will be gone within 200 to 500 years – for a moderate emissions scenario that assumes Earth’s greenhouse gas emissions will peak at 2040, the ice cap is predicted to melt in 300 years.

‘The geological data is pretty clear that the Barnes Ice Cap almost never disappears in the interglacial times,’ Professor Miller said.

‘The fact that it’s disappearing now says we’re really outside of what we’ve experienced in 2.5-million-year interval.

‘We are entering a new climate state,’ he said.

Professor Alexis Ault, an Assistant Professor at Utah State University's Department of Geology, on the Barnes Ice Cap. In this new study, the researchers used their model to estimate when the ice cap would melt under different greenhouse gas scenarios

Professor Alexis Ault, an Assistant Professor at Utah State University’s Department of Geology, on the Barnes Ice Cap. In this new study, the researchers used their model to estimate when the ice cap would melt under different greenhouse gas scenarios

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