By now, sadly, we're used to news like this. But yet another huge ice shelf, in place for over 3 millennia, is on the verge of collapse. New cracks have been discovered in the Ward Hunt Ice Shelf, on the northern coast of Ellesmere Island in Canada. At 443 square kilometers, this shelf is even larger than the 415 sq. km. one in Antarctica that collapsed last month and received a good bit of press (including here) and its "sister", the huge Ayles Ice shelf, that stunningly broke off in less than an hour about 20 months ago threatening oil rigs and shipping in the Beaufort Sea.
Scientist have known this shelf was in danger for a while. It has been slowly deteriorating for decades (and before that, it's "parent", the enormous Ellesmere Ice Shelf), and cracked in two in 2002, draining a huge freshwater lake. However, scientists were recently surprised to discover that in the past few months, it has fractured into dozens of deep new, multi-faceted cracks. They will release their findings in a report today.
I highly suggest going to the Star article and watching the video clip. More from that article:
"We were expecting to see one new crack," said Stern. "But when we flew over, all of a sudden ... there's one, there's another one.
"There are not just a couple of parallel cracks. It's multifaceted cracking going on. I was just totally amazed to see them all."
...
"The map of Canada has changed," said Derek Mueller of Trent University, who was amazed to find how quickly the shelf has deteriorated since he discovered the first crack in 2002.
...
That suggests climate change in the area has crossed some kind of threshold, he added.
Sound familiar?
I don't know how many more of these "warnings" we're going to get.
Update [2008-4-12 16:33:26 by shock]: Here is a link to the Northern Ellesmere Ice Shelves Ecosystems and Climate Impacts project page (were Dr. Mueller works) with images, videos and articles about their recent expeditions (two of which are below). I imagine that is where the findings referred to in the Star article will be released. Also, Toronto's Globe and Mail has a little more on the story here, than the Star did (but the Star has the video clip link).
[Image: Map of northern Ellesmere Island showing five of the six ice shelves in July 2005, prior to loss of Ayles Ice Shelf. The Markham Ice Shelf is not shown, it lies to the east of the Ward Hunt Ice Shelf. Black indicates extent of ice shelf, grey indicates land fast sea ice. © Derek Mueller. Source.]
[Image: A crack on the Ward Hunt Ice Shelf at its northern calving front (August 2005). © Derek Mueller. Source.]