Cool summer slowed Arctic melt

This year has seen a notable slowdown in the rate at which the Arctic sea ice cover has shrunk during the summer, compared with recent years, although this year’s Arctic sea-ice extent minimum remains consistent with a continuing decline rate of about 14 percent per decade.

At 2.07 million square miles, this year’s ice extent minimum was 664,000 square miles more than the record minimum set in 2012, according to the National Snow and Ice Data Center, or NSIDC. The melt of the onshore Greenland ice sheet also slowed this year, NSIDC said.

NSIDC said this year’s slowdown resulted from relatively cool and stormy Arctic summer weather.

In fact, the Arctic sea ice extent through May exhibited a similar pattern to that in 2012. But unusually low atmospheric pressures over much of the Arctic Ocean from June to August brought an extensive cloud cover and, hence, lower than normal temperatures. And wind patterns associated with the low pressure tended to cause the sea-ice cover to spread out, NSIDC said.

The pattern of ice thickness, a critical factor in ice longevity, remained similar to previous years. In fact, satellite radar telemetry data showed that during this year’s spring melt season the Arctic ice cover was thinner than in any previous year, NSIDC said. However, this year’s summer wind pattern resulted in thick, multiyear ice remaining in a relatively compact area along the Canadian Archipelago, rather than become broken and dispersed in the Beaufort and Chukchi seas.

It would take several more consecutive years of cool conditions to build the ice cover back to the state it was in during the 1980s, NSIDC said.

—Alan Bailey