Scientists: More Antarctic Ice Shelves Are at Risk

March 26, 2002 -- Scientists, still shaken by last week's news that a Rhode Island-sized ice shelf had splintered and sloughed into the sea, warn that more ice break-ups probably lie ahead.

"We just saw how a small amount of warming that doesn't seem like a big deal can cause billions of tons of ice to fragment and disappear," said Ted Scambos, a glaciologist at the National Snow and Ice Data Center. "Now we know there's potential for break-ups to happen rapidly."

The collapse of Antarctica's Larsen B ice shelf led to the disintegration of about 720 billion tons of ice in a 35-day period. In 1995, the northernmost section of the Larsen shelf on the Antarctica Peninsula, known as Larsen A, broke off in a similarly dramatic fashion. Now Scambos is concerned the last remaining and largest section of the shelf, Larsen C, could be next to go.

"Larsen C is the next area to watch," he said, explaining that the Antarctic Peninsula "sticks out like a thumb" in the water and so is more affected by climate change.

Cracking Points

Research has shown that increased temperatures have lengthened the melting season at the Antarctic Peninsula over the past five decades. The warming causes pools of water to melt on the ice's surface during Austral summers and these pools exert pressure on existing cracks on the ice.

"It's like a pane of glass that's shattered and is waiting to be tapped," Scambos said. This mechanism is likely what caused Larsen A and B to crumble and it could soon have the same effect at Larsen C.

Meanwhile, Tim Naish, a New Zealand climate researcher, is focused on a potentially more catastrophic collapse at the continent's Ross Ice Shelf. This western shelf — Antarctica's largest — covers about 332,000 square miles or an area about the size of France. Since much of the shelf sits on the continental shelf and is not already floating, its collapse into the ocean could lead to a potential 15- to 20-foot rise in sea level.

A study released in January revealed the Ross Ice Shelf might have been thickening as several major ice streams increased their flow from the South Pole into the continent's outer ice wedge. But follow-up observations show this flow has slowed or even frozen to a halt in places.