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Researchers Discover Ice Stream Reversal

A Cool Time in Antarctica

One place that is not a hot spot for energy exploration — or anything else, for that matter — is Antarctica.

Geologists, however, are generally attracted to their field not simply for the practical applications their knowledge can yield, but for the knowledge itself; and, after all, science pursued as an end in itself often results in unanticipated practical benefits in the future.

Which brings us back to Antarctica.

Ted Scambos, who has a Ph.D. in geology and a considerable background in energy exploration, is currently a research scientist with the National Snow and Ice Data Center at the University of Colorado, Boulder, and he loves it when, in his pursuit of pure science, he discovers that something that is supposed to be impossible to occur, has occurred.

For instance, it's supposed to be virtually impossible for a river or stream to stop its flow and reverse course — but don't tell that to Scambos and his team of Antarctic researchers.

They found an ice stream in Antarctica that has done precisely that during the past 2-1/2 centuries, and Scambos and his colleagues are trying to figure out exactly why.

"It's quite remarkable that an ice stream would reverse its flow direction," says co-researcher Howard Conway, a glaciologist and professor in the air and space science department at the University of Washington, Seattle.

Others on the five-member team include Charles Raymond (a professor) and Ginny Catania (doctoral candidate), both in the same UW department; and Hermann Engelhardt, senior research associate in geophysics at CalTech.

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One place that is not a hot spot for energy exploration — or anything else, for that matter — is Antarctica.

Geologists, however, are generally attracted to their field not simply for the practical applications their knowledge can yield, but for the knowledge itself; and, after all, science pursued as an end in itself often results in unanticipated practical benefits in the future.

Which brings us back to Antarctica.

Ted Scambos, who has a Ph.D. in geology and a considerable background in energy exploration, is currently a research scientist with the National Snow and Ice Data Center at the University of Colorado, Boulder, and he loves it when, in his pursuit of pure science, he discovers that something that is supposed to be impossible to occur, has occurred.

For instance, it's supposed to be virtually impossible for a river or stream to stop its flow and reverse course — but don't tell that to Scambos and his team of Antarctic researchers.

They found an ice stream in Antarctica that has done precisely that during the past 2-1/2 centuries, and Scambos and his colleagues are trying to figure out exactly why.

"It's quite remarkable that an ice stream would reverse its flow direction," says co-researcher Howard Conway, a glaciologist and professor in the air and space science department at the University of Washington, Seattle.

Others on the five-member team include Charles Raymond (a professor) and Ginny Catania (doctoral candidate), both in the same UW department; and Hermann Engelhardt, senior research associate in geophysics at CalTech.


Scambos said that, geologically, he likens the rifts beneath the West Antarctic Ice Sheet to the East African rift system, though not as active.

"The whole system is set up on thin continental crusts, with the elevation low relative to sea level," he said.

The last time there was open water was in the Miocene period, maybe even the Pliocene and Pleistocene periods, he explained.

"There have been several stages of open water over the past several million years," he said, "and there has been unconsolidated marine sediments deposited of the now dormant rift system, which is like the Nevada low plains and high mountains.

"You have unconsolidated marine sediment over a series of troughs, with a bunch of ice on top," Scambos continued.

"As warming began at the end of the Ice Age, there has been more flow from the large glaciers. The ice starts to warm at its bottom, releasing a thin film of water. The system has loss about half its mass, and has been quite dynamic over the past few centuries, though we're not out of the last Ice Age just yet."

Satellite data gave a good indication of the stream reversal, Scambos said, and that resulted in a grant from the National Science Foundation to study the matter.

The West Antarctic Ice Sheet, near the Ross Sea, was one of four areas the researchers visited.

"We wanted to first identify recent histories, to try to understand the entire draining process, to see whether it was speeding up or slowing down, so we could put it all into a computer model," Scambos said, "but this is a tough system to model, for it's so complex. The stream flowing backward is just one aspect of that."

Incidentally, these "streams" are much larger than glaciers, 30 to 40 miles wide and hundreds of miles long.

The point of investigation, Scambos said, was the nature of two ice streams flowing from east to west. The facts are:

  • The one to the north is called Whillans, and the one to the south C.
  • About 300 years ago the Whillans ice stream was dominant, directing the flow to C.
  • About 250 years ago the configurations of the streams changed; the Whillans ice stream thinned substantially, and C slowed dramatically and thickened, because other tributaries continue to flow into it.
  • Ice Stream C-Zero, a tributary of the larger stream C, used to flow into C at what is regarded as a fast rate of at least 100 meters (325) feet a year — a pace fast enough to open crevasses in the ice.
  • C dramatically thickened because of other tributaries flowing into it, however, and it rose higher, acting as a dam to C-Zero, thus deflecting the flow from C-Zero into the adjacent Whillans stream — at the rate of 20 meters a year.

"We think it's in response to long-term climate changes, but also to the internal dynamics of the ice sheet," Conway said. "It responds like a river system might. We just have to be careful using shorter term observations to make conclusions about long-term changes of the ice sheet."


There is some uncertainty of what the whole thing means.

In a paper the researchers published in 1999, they indicated that the fast-flowing streams that rapidly move ice from the interior of the ice sheet to the ocean are one of several methods by which Antarctica is losing its mass. The West Antarctic Ice Sheet, as large as Texas and Colorado combined, has shrunk substantially the last 7,500 years, and the paper indicated that it could disintegrate entirely within 7,000 years, raising global sea levels 15 to 20 feet.

It remains unclear, however, what role humans are playing in this. Scambos said that the problems associated with global warming aren't at play here.

"Most of Antarctica is so cold so that even if you do increase the temperature a lot, you're still below freezing," he said.

There are some exceptions to this, however, on the Antarctic Peninsula, but the real areas to watch are those like Greenland and the Arctic. For the rapid melting causes not simply greater discharges of water, but an internal fracturing that can cause greater disturbances and rapidly increase the discharges.

Scambos believes that the researches on the Antarctic ice stream reversals and eventual models can be of predictive value in the Arctic and other more volatile areas.

The current expeditions took place in 2000-01 and again in 2001-02. The team drove their snowmobiles with generators, equipment, gear and tents around a 350 mile circle, setting up camp in different places to gather data from ice penetrating radar and global positioning sensors placed on poles in the ice. The expeditions took place in November, December and January — Antarctica's spring and summer.

Temperatures range from 0-20F, "no picnic," Scambos said, "but bearable."

There was not much company in terms of wild life, nor spare time; data was gathered by day and analyzed at night. Bad weather meant they had to stay inside with their computers, VCRs and CDs — or simply to talk.

Scambos said the researchers did take time off, however, for birthdays and holidays. They even thawed Cornish hen for their Thanksgiving dinner.

The celebration beverage of choice was malt scotch, because it doesn't freeze. The vacation destination of choice after leaving Antarctica was the South Pacific Islands.

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