Antarctic ice shelf in peril as bridge snaps

By Michael Vincent for AM

ABC News Online, Posted 6 April 2009

• http://www.abc.net.au/news/stories/2009/04/06/2535739.htm
• Audio: Antarctic ice bridge rupture heightens concern about global warming (AM)
• Audio: US scientist Ted Scambos talks to Linda Hunt about the ice break. (ABC News)

The Wilkins Ice Shelf in Antarctica is in the final stages of collapse and scientists are concerned the event shows climate change is happening faster than previously thought.

An ice bridge, up to 40 kilometres long but at its narrowest just 500 metres wide, was thought to be holding the giant shelf to the Antarctic continent but it recently snapped.

From above, parts of the Wilkins Ice Shelf now look like giant panes of shattered glass.

British Antarctic Survey glaciologist Professor David Vaughan has been monitoring the Wilkins Ice Shelf for some time with the help of satellite imagery.

"The ice shelf has almost exploded into a large number, hundreds of small icebergs," he said.

"The images on the European Space Agency website show that the ice bridge was relatively stable for the past month or two.

"In fact we visited the ice bridge - we landed on it with an aircraft and put a GPS, a satellite positioning system, onto the ice shelf. And that's another way we've been monitoring its movements over the last few weeks."

Researchers believe the ice bridge was an important barrier, keeping the rest of the ice shelf in place.

Dr Ted Scambos, the lead scientist at the National Snow and Ice Data Centre at the University of Colorado, told ABC Radio National he was concerned.

"The follow on is that large chunks of ice break away from the area that's become unstable because it's no longer braced," he said.

"And we see a retreat to a smaller ice shelf, or perhaps no ice shelf at all. It's in the last stages. Right now I think about half the Wilkins will remain after this is done."

The size of the impact on sea levels is still being debated but scientists believe climate change is affecting the Antarctic to a greater extent than previously expected.

Events on the Antarctic peninsula have prompted the US Interior Secretary, Ken Salazar, to release a statement saying it "demonstrates once again the profound effects our planet is already experiencing, more rapidly than previously thought, as a consequence of climate change".

Dr Scambos says the question still remains as to what extent greenhouse gases are leading the way in terms of climate change.

"You can't make that determination on the basis of watching something like the Wilkins break-up alone," he said.

"But when you take the overall picture of earth climate changing virtually everywhere and at a rather rapid rate, and at the same time see greenhouse gases increasing in the atmosphere at a rapid rate, the correlation between those two things and the logical progression of events that you anticipate for models all point to human cost."

'A stark reminder'

Federal Climate Change Minister Penny Wong says the break-up of the ice shelf will not prompt a speed-up of the Government's climate change policies, but it should alert those who do not believe in global warming to its dangers.

"This is a stark reminder to those politicians who don't want action on climate change that we need action," she said.

"We have a great many people still who are in denial on this issue - this is a stark reminder of why we must act."

Greenpeace says the break-up of the Wilkins Ice Shelf should encourage authorities to tackle climate change at a quicker pace.

Steve Campbell, the head of campaigns for Greenpeace Australia-Pacific, says the event represents a broader warning to developed countries.

"Big developed countries such as Australia are going to need to make big CO2 cuts ... to commit to something like halving our CO2 emissions by 2020," he said.

"We're going to have to ... break our addiction to coal and we're going to have to move to a new green economy based on renewables."