Arctic Ice Melt Close to Record Low

Sept. 6, 2006 — For the second year in a row, Earth's northern ice cap has shrunk alarmingly — closely following the record-setting ice losses last year, according to the National Snow and Ice Data Center.

Slightly cooler temperatures in August may keep the melting of sea ice in the Arctic Ocean from breaking the 2005 sea ice minimum record, say experts. In 2005 the ice shrank to an area of about 2 million square miles. Right now it's at less than 2.5 million square miles, and still shrinking, according to data from the National Snow and Ice Data Center (NSIDC).

The average ice area low from 1979 to 2000 (the period when satellite data is available) was nearly 3 million square miles of sea ice. The lowest ice coverage typically happens in early September.

"We’re not down to the 2005 record value, but we’re still pretty close," said NSIDC sea ice researcher Mark Serreze. January through July was particularly warm in the Arctic this year, he said, which "does not bode well."

In August, however, a low pressure system over the Arctic Ocean blew the ice around and spread it out, reflecting more sunlight and making conditions somewhat cooler.

"Maybe things will stabilize," said Serreze.

And while that’s good news, it’s barely so. "Certainly 2006 is continuing this pattern of big ice loss," said Serreze.

The ultimate cause of the sea ice melting, polar scientists agree, is global warming. The specifics about just how it melts the sea ice, however, are a bit trickier, said Ignatius Rigor of the Polar Science Center at the University of Washington in Seattle.

There is a laundry list of ways global warming can melt sea ice.

Among them are 1) by simply warming winter air temperatures, 2) opening up more water, which absorbs more sunlight than ice and then melts more ice, 3) those same open waters leading to thinner, more easily melted ice in winter, 4) all of that thinner ice melting in the summer, 5) broad changes in seasonal wind patterns (also known as the Arctic Oscillation) that can flush out older, thicker and more durable ice, and 6) warmer waters from the Pacific and Atlantic Oceans seeping into the Arctic Ocean.

Most researchers believe it’s shifting combinations of these factors — all of which can be traced to global warming — that is causing the sea ice to disappear.

"I really think the big kicker is the high Arctic Oscillation in the early 1990s, which flushed most of the older, thicker sea ice out between 1989 to 1991," said Rigor. "Then during the late 1990s, without this store of older thicker ice to re-circulate back to the Alaskan coast, we saw enhanced melting since there just was not as much sea ice to survive the summer melt."

So even with cooler summers in 2002 and 2003, there were still huge decreases in sea ice north of Alaska.

One thing that’s clear is that the process builds up momentum each year and therefore becomes a cycle that could be impossible to stop, explained Serreze.

"What happens in one year can carry over into the next year," said Serreze. And since 2005 was a record sea ice minimum, it’s not particularly surprising that 2006 is almost as bad.