Old Arctic ice lost through Greenland-Ellesmere gap

RANDY BOSWELL
Canwest News Service
Special to Nunatsiaq News

A team of international scientists is sounding alarms about the state of a natural ice dam in northeastern Canada that has historically prevented older, thicker Arctic Ocean sea ice from drifting south through a narrow passage along Ellesmere Island and melting in warmer waters.

A study by U.S. and Danish researchers — including NASA’s leading experts on the polar ice cap — describes how the Nares Strait “ice arches” failed to form during the winter of 2007 in the 35-kilometre gap between Ellesmere and the northwest coast of Greenland.

Sea ice typically consolidates in distinctive, curved structures at the north end of the strait.

But when the blockage failed to materialize as usual in 2007 — the same year a record-setting Arctic thaw first raised global concern about polar warming — the central Arctic Ocean discharged double the average annual amount of sea ice through Nares Strait, the researchers found.

“We don’t completely understand the conditions conducive to the formation of these arches,” said NASA ice expert Ron Kwok, lead author of the study, which was published in the latest issue of the journal Geophysical Research Letters.

“We do know that they are temperature-dependent because they only form in winter. So there’s concern that if climate warms, the arches could stop forming,” Kwok said.

While most central Arctic sea ice exits through the 400-km-wide Fram Strait between Greenland and the Svalbard Islands, the researchers found that ice flushing through Nares Strait in 2007 — according to a 13-year satellite record of polar ice cover — amounted to a record 10 per cent of the total loss.

“Until recently, we didn’t think the small straits were important for ice loss,” Kwok said in a summary of the team’s research.

“If indeed these arches are less likely to form in the future, we have to account for the annual ice loss through this narrow passage. Potentially, this could lead to an even more rapid decline in the summer ice extent of the Arctic Ocean.”

The Canadian Ice Service recorded the 2007 absence of the ice arches and has also observed “quite unusual” ice movement each year since along the strait.

“One of our most important goals is developing predictive models of Arctic sea ice cover,”said NASA researcher Tom Wagner.

“Such models are important not only to understanding changes in the Arctic, but also changes in global and North American climate. Figuring out how ice is lost through the Fram and Nares straits is critical to developing those models.”