[extropy-chat] global warming, with ice

[Damien Broderick]

Perhaps the hothouse skeptics will have a view on this report?

=======================

http://www.theage.com.au/articles/2006/12/29/1166895467195.html?page=fullpage#contentSwap1


Giant ice shelf snaps

December 29, 2006 - 2:57PM

A giant ice shelf the size of 11,000 football fields has snapped free 
from Canada's Arctic, scientists said.

The mass of ice broke clear 16 months ago from the coast of Ellesmere 
Island, about 800 kilometres south of the North Pole, but no one was 
present to see it in Canada's remote north.

Scientists using satellite images later noticed that it became a 
newly formed ice island in just an hour and left a trail of icy 
boulders floating in its wake.

Warwick Vincent of Laval University, who studies Arctic conditions, 
travelled to the newly formed ice island and could not believe what he saw.

"This is a dramatic and disturbing event. It shows that we are losing 
remarkable features of the Canadian North that have been in place for 
many thousands of years. We are crossing climate thresholds, and 
these may signal the onset of accelerated change ahead," Vincent said today.

In 10 years of working in the region he has never seen such a 
dramatic loss of sea ice, he said.

The collapse was so powerful that earthquake monitors 250 kilometres 
away picked up tremors from it.

The Ayles Ice Shelf, roughly 66 square kilometres in area, was one of 
six major ice shelves remaining in Canada's Arctic.

Climate change link

Scientists say it is the largest event of its kind in Canada in 30 
years and point their fingers at climate change as a major contributing factor.

"It is consistent with climate change," Vincent said, adding that the 
remaining ice shelves are 90 per cent smaller than when they were 
first discovered in 1906.

"We aren't able to connect all of the dots ... but unusually warm 
temperatures definitely played a major role."

Laurie Weir, who monitors ice conditions for the Canadian Ice 
Service, was poring over satellite images in 2005 when she noticed 
that the shelf had split and separated.

Weir notified Luke Copland, head of the new global ice lab at the 
University of Ottawa, who initiated an effort to find out what happened.

Sudden collapse

Using US and Canadian satellite images, as well as data from seismic 
monitors, Copland discovered that the ice shelf collapsed in the 
early afternoon of August 13, 2005.

"What surprised us was how quickly it happened," Copland said.

"It's pretty alarming. Even 10 years ago scientists assumed that when 
global warming changes occur that it would happen gradually so that 
perhaps we expected these ice shelves just to melt away quite slowly, 
but the big surprise is that for one they are going, but secondly 
that when they do go, they just go suddenly, it's all at once, in a 
span of an hour."

Within days, the floating ice shelf had drifted a few kilometres 
offshore. It travelled west for 50 kilometres until it finally froze 
into the sea ice in the early northern winter.

The Canadian ice shelves are packed with ancient ice that dates back 
over 3,000 years. They float on the sea but are connected to land.

Derek Mueller, a polar researcher with Vincent's team, said the ice 
shelves got weaker and weaker as the temperature rose. He visited 
Ellesmere's Ward Hunt Ice Shelf in 2002 and noticed it had cracked in half.

"We're losing our ice shelves and this a feature of the landscape 
that is in danger of disappearing altogether from Canada," Mueller said.

"In the global perspective Antarctica has many ice shelves bigger 
than this one, but then there is the idea that these are indicators 
of climate change."

The spring thaw may bring another concern as the warming temperatures 
could release the ice shelf from its Arctic grip.

Prevailing winds could then send the ice island southwards, deep into 
the Beaufort Sea.

"Over the next few years this ice island could drift into populated 
shipping routes," Weir said.

"There's significant oil and gas development in this region as well, 
so we'll have to keep monitoring its location over the next few years."

AP