WHAT THE ICE CORES WILL REVEAL

The section of core, no more than a meter in length, is brought to the surface and immediately sealed to prevent contamination.

To recap, this summer three teams are drilling ice cores in the proximity of Mt. Logan, Canada's highest mountain. A Canadian team (ICE2001) returned to the high-altitude Prospector-Russell Col (5,300 meters above sea level). A Japanese team is at the nearby King Col site (4,200 m). An American team is at the Eclipse site (3,000 m), where they will drill two cores.

International cooperation in science is well demonstrated by the ICE2001 project. Canada had invited the United States and Japan to share in the opportunity to learn from the ice fields around Mt. Logan. Canada bears less than one-quarter of the costs of the Logan activities thanks to contributions in staff, equipment and funding by the other countries' scientific organizations. All partners will share in the results of their work, providing valuable information on the past climate record. Some expected findings are described below.

The snow accumulation record from P-R Col, King Col and Eclipse will reveal, for the first time, the history of past snowfall over thousands of years in the northwest of the continent. We will learn what it was like in the early Holocene (the geological period 8,000-12,000 years before the present), when it was warmer than today.

One of the stops enroute to the camp at Prospector-Russell Col.

The warmth of past summers at each of the three elevations (5,300 m, 4,200 m and 3,000 m) will be deduced from the presence and thickness of melt layers. Even at these high elevations, some surface snow melts - and then refreezes - during a short interval each summer. Each elevation experiences different melting regimes and comparison of all three will tell much about the variations of the summer temperatures in both space and time.

Low concentrations of ocean salts are present in the atmosphere, having been derived from the ocean's surface, especially during high wave action. The salts are carried afar by air movements, eventually being deposited back on the earth's surface, including the ice fields of Mount Logan. From the analysis of the ice cores, scientists calculate the past concentration of these salts in the atmosphere. From this and other information, such as the deposition records from other North American sites, the past ocean temperatures and wind regimes can be inferred.

The climatic differences between the western and eastern Arctic, which are significant, will be further illuminated by comparing the Logan cores with several existing cores from Canada's Arctic archipelago. This will help us understand the causes of the recent accelerated warming of the western Arctic, including whether or not similar changes have occurred in the past.

In addition to helping understand the dynamics of climatic change, the work on Logan will also contribute to assessing some of the probable impacts of future climate changes. For example, changes in snow accumulation and melt over time will help in assessing the reduction in glacier contributions to river flows in western Canada, while changes in temperature and wind regimes should provide insights into the climatic controls of sea ice cover in the western Canadian Arctic.

THIS WEEK'S UPDATE OF ACTIVITIES ON LOGAN

Significant events are coming fast.

Drilling has been completed at the Canadian high-altitude drill camp of Prospector-Russell Col. Bedrock was reached at about 187 m depth, somewhat less than anticipated. The team reported that the very bottom of the core was very easy to drill; this is typical of ice-age ice, which would be a great find (first photo). The packaged core, together with all the drill and camp equipment, should be flown out by helicopter in a week - assuming the Logan weather permits it! When the helicopter has done its job, the crew will ski back to the Quintino Sella base camp - much faster than the laborious trip in to the core site earlier this summer (second photo).

Even the rare level area among the mountains has a tortured surface from the fierce winds of the never-ending parade of storms from the Pacific.

King Col has seen the arrival of Canadians Justin Koerner and Simon Meis from P-R Col and Mike Demuth and Fritz Koerner from the lower camp at Quintino Sella. The Japanese team has also completed drilling, having reached the maximum 220 m depth permitted by their drilling cable. Although this is not the full thickness of the ice at that site, it is likely very near the bedrock. They are now preparing to break camp and return. Their core, too, will soon be flown out for shipment to Japanese laboratories for analysis.

The American team at Eclipse has now recovered an impressive 336 m of ice core. The team is still drilling, although equipment imposes a 350 m limit. The core from this hole will be analyzed for trace metals, such as mercury and iron. When they have finished recovering this core, the team will drill a second core at the same location. The second core, to be kept to 100 m in length, will be analyzed for organic molecules. Although they are both recovered in the same way, cores destined for analysis of metals must be handled and packaged quite differently from cores destined for analysis of organics.

Next week's update will paint a quite different picture of activities on the mountain!