Arctic sea ice melt comes close, but misses record

Yahoo News 16 Sep 08;

Crucial Arctic sea ice this summer shrank to its second lowest level on record, continuing an alarming trend, scientists said Tuesday.

The ice covered 1.74 million square miles on Friday, marking a low point for this summer, according to NASA and the National Snow and Ice Data Center in Boulder, Colo. Last summer, the sea ice covered only 1.59 million square miles, the lowest since record-keeping began in 1979.

Arctic sea ice, which floats on the ocean, expands in winter and retreats in summer. In recent years it hasn't been as thick in winter.

Sea ice is crucial to worldwide weather patterns, both serving as a kind of refrigerator and reflecting the sun's heat. Given recent trends, triggered by man-made global warming, scientists warn that within five to 10 years the Arctic could be free of sea ice in the summer.

Even though the sea ice didn't retreat this year as much as last summer, "there was no real sign of recovery," said Walt Meier of the snow and ice data center. This year was cooler and other weather conditions weren't as bad, he said.

"We're kind of in a new state of the Arctic basically, and it's not a good one," Meier said. "We're definitely sliding towards a point where the summer sea ice will be gone."

Arctic Sea Ice Shrinks to Second Lowest on Record
Andrea Thompson, LiveScience.com Yahoo News 16 Sep 08;

Sea ice coverage over the Arctic has reached its lowest point for the year, coming in second only to 2007 for the lowest ice extent recorded since 1979, scientists announced Tuesday.

The latest low was recorded on Sept. 12, when the region's sea ice extent dropped to 1.74 million square miles (4.52 million square kilometers). This appears to be the low point for the year, as ice has started to reform in response to autumn cooling in the Arctic, according to the National Snow and Ice Data Center (NSIDC), which monitors sea ice extent.

The 2008 minimum is the second-lowest recorded since 1979, when satellite coverage began, and is 0.86 million square miles (2.24 million square kilometers) below the 1979 to 2000 average minimum.

The record minimum came on Sept. 16, 2007, when sea ice extent was reduced to an estimated 1.65 million square miles (4.28 million square kilometers) - 9.4 percent lower than this year's estimated minimum.

Though the ice did not melt this year to a record low, it is further evidence of the overall downward trend in sea ice extent in recent decades, the NSIDC said in a statement. Arctic sea ice has also been thinning, as older, thicker ice melts away and the ice that reforms each winter is thinner perennial sea ice that melts away again in the summer. Scientists attribute this trend to the rise of global temperatures caused by the increase of greenhouse gases in Earth's atmosphere.

The pattern of ice melt this year was different than in 2007. This year did not have the substantial ice loss in the central Arctic, north of the Chukchi and East Siberian Seas. However, 2008 did see greater loss in the Beaufort, Laptev and Greenland Seas.

Both years saw the opening of the shallow Amundsen's Northwest Passage, but the deeper Parry's Channel of the Northwest Passage did not quite open in 2008.

This year saw another opening though: the Northern Sea Route, the passage through the Arctic Ocean along the coast of Siberia.

While the Sept. 12 minimum appears to be the minimum for the entire year, further melting could occur later. In 2005, for example, the ice extent appeared to reach a minimum in early September, but the ice contracted later in the season, creating a new minimum.

No 2008 record for Arctic sea ice
Richard Black, BBC News 16 Sep 08;

Sea ice in the Arctic appears to have passed its minimum extent for 2008 without breaking last year's record.

The US National Snow and Ice Data Center (NSIDC) says the ice covered 4.5 million sq km (1.7 million sq miles) at its lowest point on 12 September.

Last year's minimum was 4.1 million sq km (1.6 million sq miles).

This summer's ice cover was the second lowest since satellite records began 30 years ago, which NSIDC says emphasises the "strong negative trend".

Temperatures have been lower in the Arctic this year than in 2007, largely because of La Nina conditions, which create a colder climate globally from their source in the Pacific.

"I think this summer has been more remarkable than last year, in fact, because last year we had really optimal conditions to melt a lot of ice," said Walt Meier, a research scientist at NSIDC in Boulder, Colorado.

"We had clear skies with the Sun blazing down, we had warm temperatures, and winds that pushed the ice edge northwards," he told BBC News.

"We didn't have any of this this year, and yet we still came within 10% of the record; so people might be tempted to call it a recovery, but I don't think that's a good term, we're still on a downwards trend towards ice-free Arctic summers."

No laughing matter

Even with cooler conditions anticipated, scientists had predicted at the beginning of the Arctic summer that last year's record might be broken, because much of the ice was thinner than usual, having formed during only a single winter.

Instead, the 2008 graph now appears to be indicating the beginning of an expansion from the 12 September minimum, as the Arctic autumn sets in.

The NSIDC team will continue to monitor the ice area and will release a full analysis towards the end of this month.

The end of this summer will probably find the ice in a marginally healthier state than at this time last year. Some of the thin floes remaining will presumably thicken during the winter, leaving the ice a little more robust.

With governments around the Arctic now seeking economic opportunities from a navigable ocean and a sea bed open to exploration, an important question is when the region will become ice-free in summers.

A few years ago, most computer models of climate were projecting dates about 80 years hence. Then, as the melt rate accelerated around the turn of the millennium, the projected date advanced to about 2040.

Now, some climate modellers expect to see nothing but open water within five years.

"To my mind that's a bit aggressive, but certainly not impossible," said Dr Meier.

"Five years ago that would have got someone laughed out of the room; but no-one's laughing now."