CU Boulder study: Last piece of North American ice sheet will be gone in a few hundred years

BOULDER, Colo. – The last remaining piece of the ice shelf that once covered much of North America could be gone in as little as 200 years, according to a new study from scientists at CU Boulder and Simon Fraser University in British Columbia.

The Barnes Ice Cap on Baffin Island in the Canadian Arctic is currently about the size of Delaware and is 500 meters thick. It’s part of an ice sheet that has grown and shrunk over the years and as of about 20,000 years ago, it was about a mile thick where Chicago now sits.

CU Boulder scientist Gifford Miller and the study’s co-authors estimate that under any possible greenhouse gas emission scenario, the Barnes Ice Cap will be gone in 200 to 500 years. Using a model in which greenhouse gas emissions peak around the year 2040, the scientists estimated the ice cap would be gone in about 300 years.

Even if humans are able to reduce their greenhouse gas emissions, it wouldn’t save the ice cap, the scientists say, marking a monumental change for an ice sheet that has been around for 2.5 million years or so.

“The geological data is pretty clear that the Barnes Ice Cap almost never disappears in the interglacial times,” 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.”

By studying isotopes created by cosmic rays that have been trapped in rocks around the ice cap, scientists estimate that it’s only been as small as it is now three times during its lifetime.

The melting of the Barnes Ice Cap isn’t likely to have a noticeable effect on sea levels, but its demise could be bad news for larger ice sheets like those on Greenland and Antarctica, which have a more direct effect on rising sea levels.

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

The study is available online from the journal Geophysical Research Letters.