Is there a link between the iceberg and climate change?

ICE oozes across the surface of Antarctica and breaks off into the southern oceans constantly – but not normally in chunks the size of Delaware.

So after a massive iceberg separated from the Antarctic peninsula last week, the burning question among glacial scientists is: Was it influenced by warming seas or air, or was its separation just an abnormally dramatic stage in the natural evolution of Earth’s southern ice cap?

Though the divorce was captured by multiple satellites, researchers have little data on what might have caused it or the long list of potential factors behind it, including not just temperatures but the speed and directions of winds, currents and glacial flows.

Pools of water and other signs of thinning have preceded major losses in other parts of the same ice shelf since the 1990s, but not this time. Scientists said the iceberg’s size demands further study as they look to forecast whether it suggests a coming acceleration in sea level rise.

“It’s a pretty amazing chunk of the coastline of Antarctica,” said Christopher Shuman, a research scientist with the University of Maryland, Baltimore County who is based at the Nasa Goddard Space Flight Center in Greenbelt.

“We’ll be watching to see if there are signs that other rifts are getting activated or if the flow field from glaciers begin to accelerate,” Shuman said. “That would begin to tell us that, ‘Hey, things are probably going to change more in the future.’”

Scientists are interested in watching what happens next, though they said it could take years to reach conclusions on what is shaping the ice shelf.

Kelly Brunt, a glaciologist with the Earth System Science Interdisciplinary Center at the University of Maryland based at Goddard, plans to use data on glaciers’ altitude to watch whether the flow toward the Larsen C shelf increases. That would indicate that the iceberg was holding back a flow of ice that could now pour into the ocean, potentially accelerating ice loss and sea level rise.

But she said it’s also possible the iceberg broke off as part of a normal process known as calving, in which ice shelves splinter and then recover. That would suggest less of an influence from climate change, and could stand in contrast to the collapses of the nearby Larsen A and B ice shelves in 1995 and 2002.

“Larsen B, we can pin a little more directly to changes globally contributing to the breakdown,” Brunt said. “It is hard to do that with Larsen C.”

The Midas Project scientists suggested “a risk that Larsen C may eventually follow the example of its neighbour, Larsen B.” They likened last week’s event to one that preceded the collapse of that ice field.

Scientists have little confidence in predicting the influence the iceberg’s separation will have on ice cover going forward.

Anand Gnanadesikan, an earth and planetary sciences professor at the Johns Hopkins University, said it’s equally possible the ice loss could lead to an increase or a decrease in sea ice, whether by allowing warmer waters to reach the surface and freeze or by exposing water to more heat from the sun.

“It isn’t actually something we seem to understand very well from a fundamental physics point of view,” he said. “When something big like this happens, it’s just a reminder of that fact.”

Alek Petty, another Goddard-based scientist affiliated with the University of Maryland earth science center, said “there’s nothing to suggest this is climate change-driven.” He speculated that the more suspicious losses of Antarctic ice in recent years “might be adding to the confusion.”

“Similar size icebergs have happened before,” he said – a larger piece of Larsen C broke away in 1986. “We expect similar sized icebergs to happen in the future.”

– Tribune News Service