November 6, 2003

Team studying Antartic storm that created iceberg the size of Jamaica

Scientists from the University of Chicago, Northwestern, and the University of Wisconsin are investigating a large storm in Antarctica that caused an ice sheet to split in two, forming an iceberg the size of Jamaica.

For several years the large iceberg, named B15, looked as though it would eventually split from the Ross Ice Shelf, according to Mike Williams of New Zealand's National Institute of Water and Atmospheric research. The Ross Ice Shelf composes a large portion of the Antarctic continent.

According to Doug MacAyeal, a glaciologist in the University's geosciences division, the fact that the iceberg eventually separated from the ice shelf was not surprising. If the iceberg makes its way across McMurdo Sound, a large water body in Antarctica, it could block oceanic shipping lanes and delay scientific projects to study the Antarctic, MacAyeal said.

MacAyeal has been studying glaciology at the University since 1983, and first became interested in icebergs in 1998 while working with an undergraduate, Ben Kerman. The two investigated the possible consequences of a break occurring from the Ross Ice Shelf, located on the northern Antarctic coast near New Zealand, as it did earlier this week.

MacAyeal said that this event will have little importance other than its curiosity.

"For earth-shaking consequences, sadly I must confess that there are none that are immediately pressing," he said in an e-mail interview. However, he added that the consequences of even small changes to the Antarctic ice sheet are so drastic that they need to be monitored extremely closely.

In some cases, MacAyeal said a change in the Antarctic ice sheet could have a disastrous effect on the environment even thousands of miles away. "If the Western part of the Antarctic ice sheet were to thin by 25 percent or so, sea level would rise around the world," he said. "This would affect world coastal regions, displacing tens of millions of Bangladeshi Muslims into surrounding areas that are primarily Hindu." Scientists have been worried for years about the polar ice caps, especially with mounting discussion of global warming. Coastal cities, including New York, Miami, and Boston, would be immersed under dozens of feet of water if the ice caps melted completely.

According to MacAyeal, these climatic fluctuations are nothing new. He said that during the glacial period—roughly a period between 100,000 and 20,000 years ago—Earth's climate system went though dramatic "gyrations" in which the temperature would rise and fall with little reason.  A central cause of this gyration, he added, is thought to be discharges of icebergs from the Canadian ice sheet (through the Hudson Strait) into the north Atlantic, where the melting icebergs "spike" the normally saline ocean water with a dollop of fresh water.

MacAyeal said that he is surprised about the amount of coverage the birth of B15 has received. "I guess that the strangest thing from my perspective is that the general public and news media seems to pick up on this stuff. I got to do a radio interview for New Zealand public radio simply because the general public likes to hear about the goings-on of icebergs that are bigger than many of the small states in the U.S.," he said.

MacAyeal is currently stationed in New Zealand and is finishing up research on the iceberg. He plans to return to the University later this month.