Did climate change cause massive iceberg break?

ONE of the biggest icebergs ever recorded, a trillion-tonne behemoth more than twice the size of the ACT, has broken off from Antarctica, triggering debate about potential sea-level rises and the impact of climate change.

While such “calving” of icebergs is not unusual, this is an especially big one which covers 5800sq/km.

The iceberg broke loose from the Larsen C ice shelf after scientists watched for months as the “crack” grew more than 200km long.

Nathan Bindoff, a Professor of Physical Oceanography at the University of Tasmania and leading climate science expert, said the impact of the break would be far reaching.

“Big ’bergs breaking off the major ice shelves are a critical component of the story around the fate of the Antarctic Ice Sheet,” Prof Bindoff said.

“The ice shelves buttress the Antarctic Ice Sheet and slow the rate of ice loss from Antarctica.

“So a major ’berg like this one means we will see an acceleration of the grounded glaciers behind the Larsen C shelf. This glacier acceleration will contribute to further sea-level rise in the next few years.”

He said the “bigger picture concern” was the thinning of ice shelves around Antarctica, which implied more events like this one, and more acceleration of the glaciers that feed the ice shelves.

“To my mind, this is the million dollar question around Antarctica: how fast is it going to melt going into the future?”

Meanwhile, international scientists agreed global warming has caused a thinning of such shelves, but differed on whether the latest event could be blamed on climate change.

The iceberg is considered unlikely to pose any threat to shipping at this stage and is expected to have an immediate impact on sea levels.

Two other Antarctic ice shelves, farther north on the Antarcti c Peninsula, collapsed in 1995 and 2002.

That sped up the slide of glaciers, which conntributed toto sea-level rise, David Vaughan, ughan, director of science at the Britishh Antarctic Survey, saidd in a statement.

“Our glaciologists will now be watchingatching closely to see whether the remaining Larsen C ice shelf becomes less stable than before the iceberg broke free,” he said.

Eric Rignot, a glaciologist at the University of California said the breaking off of the iceberg “is part of a longterm major loss of the ice shelves in the peninsula, progressing southbound and resulting from climate warming”.

Professor Ian Simmonds, from the School of Earth Sciences at The University of Melbourne, described the event as “deeply troubling”.

“Temperatures have risen dramatically in the region over recent decades,” he said, resulting in summer temperatures frequently getting above freezing.

“In addition the major warming of the sub-surface Antarctic Ocean is strongly impacting on the thick ice shelves from beneath.”

But Swansea University glaciologist Martin O’Leary, a member of the MIDAS project, called it “a natural event”.

“We’re not aware of any link to human-induced cli-

mm a te change,” he said. A spokeswoman for the British Antarctic survey said there was not enough information to say whether the calving is an effect of climate change, though there’s good evidence global warming has caused thinning of the ice shelf.

Professor Pat Langhorne, an Antarctic sea ice researcher in the Department of Physics at the University of Otago, said the process had “gone on over the millennia and is the planet’s mechanism for keeping Antarctica’s ice in approximate balance”.