Posted by: JohnnyRook | July 29, 2008

Latest Ice Shelf Collapse: This One’s in the Arctic

The Associated Press has just announced that a 7 square mile piece of the Ward Hunt ice sheet, the largest ice sheet in the Arctic has collapsed. The ice sheet was first noticed to be fracturing in 2002. It was observed in April of this year that the ice shelf has broken into 3 pieces and fears were expressed that it would not survive the year. Ward Hunt is the remnant of a much larger ice sheet that surround Ellesmere Island until the beginning of the 20th century when it broke up into 6 pieces, the largest of which is the Ward Hunt, at 170 square miles and 130 feet thick.

Although small by comparison with the Antarctic ice shelves Ward Hunt has a long and storied history. The 2002 breakup was an ecological disaster as it wiped out the epishelf lake in Disraeli Fiord, a large body of freshwater that floated on top of the Arctic’s denser sea water.

Map of Ellesmere Island, Canada

According to the Globe and Mail:

(The G&M, reported that the piece that broke off was only 4 km2, but that may be only one of the three pieces)

Scientists say the break, the largest on record since 2005, is the latest indication that climate change is forcing the drastic reshaping of the Arctic coastline, where 9,000 square kilometres of ice have been whittled down to less than 1,000 over the past century, and are only showing signs of decreasing further.

“Once you unleash this process by cracking the ice shelf in multiple spots, of course we’re going to see this continuing,” said Derek Mueller, a leading expert on the North who discovered the ice shelf’s first major crack in 2002.

Aeriel view of crack on Ward Hunt ice shelf

Notice the fracture in the center of this photo from 2002. [NASA Photo)

Again from AP:

Gary Stern, co-leader of an international research program on sea ice, said it’s the same story all around the Arctic.

Speaking from the Coast Guard icebreaker Amundsen in Canada’s north, Stern said He hadn’t seen any ice in weeks. Plans to set up an ice camp last February had to be abandoned when usually dependable ice didn’t form for the second year in a row, he said.

“Nobody on the ship is surprised anymore,” Stern said. “We’ve been trying to get the word out for the longest time now that things are happening fast and they’re going to continue to happen fast.” [Emphasis–JR]

Ellesmere Island & Ward Hunt Ice Shelf

Another NASA photo of Ellesmere Island and the Ward Hunt ice shelf from 2003.

Below are two more photos from 2002, this one showing Disraeli Fiord where the epishelf lake was located.

Ward Hunt ice sheet with missing piece

NASA photos

You can see a photo of the current breakup at the Brisbane Times web site.

Currently sea ice melt in the Arctic, although well below the 1979-2000 average, is behind last year’s record pace. (Click on images in upper right of the link to see the latest image and graft. There is a one day lag, so today’s events will not be reflected in the graph until tomorrow.). Scientists, however, have remarked upon how thin the sea ice is this year. Thinner ice melts more easily, and if this latest news about the Ross Hunt ice shelf is any indicator, we may still get a record year before the summer is out.

Crossposted at Daily Kos


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