The Canada Glacier comes to an abrupt and majestic end in the Taylor Valley, in the form of a 60-foot-high wall of ice that dwarfs the tents of the climate scientists who sleep beneath it. There, in bright summer sunshine, the glacier melts steadily into a barren hillside, slowly filling Lake Hoare.

Nearby, a wooden research hut that has stood along the lake since 1978 sits boxed up for relocation because of the rising water levels. It's tough to imagine a more compelling image of the inexorable march of global warming.

Except that this part of Antarctica is actually cooling, says Andrew G. Fountain, a professor of geography and geology at Portland State University who is a top expert on the glacier. It appears that the glacier is melting because warm, wind-blown dust particles are settling on top.

"Because of the climate cooling in this part of the continent," he says, "the only reason that we're getting increased melt has to be because of these local conditions of sediment on top of glaciers."

Such surprises are not unusual in Antarctica. Of all the research projects that the National Science Foundation supports through the United States Antarctic Program, those aimed at predicting the course of climate change have emerged as a priority, whether they involve studying glaciers or uncovering historical ice records or evaluating the effects of climate change on surrounding life. And yet clear answers remain elusive.

For example, consider ARGO, a network of 3,000 free-floating buoys that measure underwater ocean temperature and salinity. It's an ambitious and creative project that relies on devices programmed to sink, take measurements, and then pop up every few days to the ocean surface, where they automatically fire off their readings by satellite.

Almost from the start of the project, says Deborah A. Bronk, a professor of marine science at the College of William & Mary, ARGO mocked scientists' poor understanding of ocean currents: The buoys followed none of the predicted travel patterns. That was a major wake-up call, she says, especially for those studying the ocean around Antarctica, where water currents—especially those well beneath the surface—play a still-poorly-understood role in regulating global temperature and climate.

The role of water flow in climate change was demonstrated on an impressive scale in 2002. That's when the huge Larsen B ice shelf, which covered 1,250 square miles at a thickness of 650 feet, suddenly collapsed along the east coast of Antarctic Peninsula.

Those who had studied Larsen had expected it to fall apart much more slowly. But they had failed to understand the amount of warming that had occurred underneath, says Wolfgang Rack, a senior lecturer for glaciology and remote sensing at the University of Canterbury, in New Zealand. "We discovered that parts could collapse within days," says Mr. Rack, who has made nine research trips to Antarctica.

The same lesson also drives the Pine Island Glacier project. Covering more than 300 square miles at several thousand feet deep, the glacier hangs off the edge of western Antarctica and is one of the continent's biggest and fastest melting glaciers. Studying it requires researchers to fly almost 1,400 miles from the main U.S. research base at McMurdo, then set up drilling equipment on the tottering glacier to get a better sense of how fast the ocean is melting it from below.

Such research efforts were identified last year in a review by the federally chartered National Research Council as centerpieces of the Antarctic Program. That's largely because the United Nations-established Intergovernmental Panel on Climate Change, the main global authority on planetary warming, has pleaded for better models for forecasting the effects of climate change, says Scott G. Borg, director of the National Science Foundation's division of Antarctic sciences.

Detailed assessments of the speed and dimensions of climate change remain important for the wider public, Mr. Borg says, even if the big-picture direction is already known—and controversial. "Just because there are difficulties in conveying the message," he says, "doesn't mean that I'm not interested in trying to have a good scientific basis for a message if someone will listen."

Another study tied to climate change is led by Jeffrey P. Severinghaus, a professor of geosciences at the University of California at San Diego, who is part of a project named for the West Antarctic Ice Sheet. Just as botanists count a tree's rings to determine its age, the WAIS researchers count annual cycles in ice.

In earlier seasons, the researchers cut deep cores of Antarctic ice, as far down as two miles, then measured the isotopes of hydrogen and oxygen to calculate temperatures at the time the ice formed. They also analyzed trapped gases to learn the corresponding concentrations of carbon dioxide. That let them determine when in the ancient past natural processes might have generated unusually large amounts of the gas, and how the earth responded temperaturewise.

This season, Mr. Severinghaus went back in search of even greater precision, cutting ice cores deposited at selected times where the interactions between atmospheric gases and temperature seemed most worthy of closer examination.

PSU Department of Geology: http://www.pdx.edu/geology/

Glacier research at PSU: http://glaciers.pdx.edu/