In several laboratories around the world, ice from a remote corner of the Yukon is being sliced, melted, sieved, peered at and probed in a dozen ingenious ways.

The goal is to extract every last smidgen of information about the climate of the Pacific region for the past thousands of years, perhaps as far back as the last ice age.

The ice comes from hundreds of metres of ice cores drilled from Mount Logan, Canada's highest mountain, in the springs of 2001 and 2002.

The Mount Logan Ice Core Project was started by the Geological Survey of Canada with the idea of retrieving one long ice core from the high icefields of Logan. However, several other nations and research institutions joined in.

Eventually, three major expeditions drilled ice cores at three different elevations on or near the mountain. An American-led team worked at 3015 metres above sea level, and a Japanese-led team drilled at 4200 metres.

Christian Zdanowicz, a researcher with the Geological Survey of Canada, was part of the Canadian team. As well as working with the other teams, the Canadians took cores from the highest elevation -- 5340 metres, or well over five kilometres above sea level.

The high ice of Mount Logan is an archive of the climate history of much of the Pacific region, says Zdanowicz.

Moisture that has evaporated into the air as far away as the equatorial regions of the Pacific Ocean is swept north and west by the prevailing winds. After traveling thousands of kilometres across the open ocean, it jams up against the coastal mountains of Alaska and the southwestern Yukon.

There, smack in its path, is the vast bulk of Mount Logan. The moisture turns to precipitation and falls as snow on the high slopes where the temperature stays below freezing all year round. As season after season of snow falls, the snows of the past are buried, compressed, and turned into ice. But they still carry information about the conditions that created them.

One key to unraveling the puzzle, says Zdanowicz, is different forms, or isotopes, of oxygen.

Water is made up of hydrogen and oxygen, but not all atoms of hydrogen and oxygen are created equal. The various different types of hydrogen and oxygen available in the atmosphere can create nine different kinds of water molecules, each distinguishable from the others.

How much of each isotope of hydrogen and, especially, oxygen is present in rain or snow is partially dependent on temperature. In places like the eastern Arctic, these isotope balances, preserved in layers of ice, are used to reconstruct the history of past temperature changes.

In the case of Mount Logan, the moisture that falls as snow can come from very distant sources, as far as the equatorial Pacific. Thus, the isotopic changes locked in the ice have probably more to do with factors controlling long-range moisture transport than with temperature.

"It's a very different pattern than in the eastern Canadian Arctic," says Zdanowicz. "In a way, we have to re-educate ourselves in looking at it."

The fact that ice cores were extracted from three different elevations will provide even more information, he adds. The snows that fall at the high elevations of Mount Logan may come from much further away than the snows that fall at lower elevations.

As a consequence, the Mount Logan ice cores will provide information about oceanic and atmospheric processes and changes that take place over a vast region of the central and north Pacific Ocean.

More than water falls in the snow. Buried in the layers of the ice cores are ash deposits from volcanic eruptions and dust particles from storms that raged across the steppes of Asia, seasonal algae growths and pollen from distant plants, even charcoal from forest fires.

"There are all sorts of stories being told at the same time," says Zdanowicz.

The initial analysis will take about a year and a half, he says. Then comes the work of figuring out exactly what the information means.

The Mount Logan research teams are planning a special scientific session in December 2004. There they will present their results to others working in the field and start brainstorming possible interpretations of the information, Zdanowicz says.

He predicts that the wealth of data locked in the ice of Mount Logan will produce new information about past climates and climate processes for years to come.

For more information about the Mount Logan Ice Core Project, go to sts.gsc.nrcan.gc.ca/ice2001.