Ice Core Analysis Shows Western Canada Warming

TORONTO, Ontario, Canada, December 2, 2002 (ENS) - Western Canada is warming up, and will continue to grow warmer at the same time as snow accumulates ever deeper on the ground, says a Canadian-Swiss research team. Analysis of an ice core drilled from Canada's highest mountain indicates that western Canada has experienced significant climate change over the past 150 years, according to their new scientific study published in the journal "Nature."

The paper furthers the argument that human activity has contributed to global warming, its authors say.

The scientists came to their conclusions after examining the ice core and calculating a "marked increase" in snow accumulation levels on Mount Logan since 1850. Increases in snow accumulation, according to the research team, are associated with a warming of the atmosphere.

Moore

Dr. Kent Moore, associate professor of atmospheric physics, University of Toronto (UT) (Photo courtesy UT)
"This seemingly paradoxical effect is due to the fact that warmer air holds more moisture that, in winter, can be released as snow," said team leader and University of Toronto physicist and associate professor Kent Moore.

Through their chemical analysis of the core, the researchers examined climate change over the past 300 years at Mount Logan. In the southwest corner of the Yukon Territory in the Saint Elias Mountains of Kluane National Park, at 5,959 meters (19,550 feet) Mount Logan is Canada's tallest point, and the second highest peak on the continent.

Moore and his team found that the average annual snow accumulation at Mount Logan remained constant between about 1700 and 1850 AD, but then increased from 1850 onward.

"We argue that this increase in snow accumulation is associated with a warming of the atmosphere over western Canada," said Moore. The researchers also say the snow accumulation was greatest in the past 10 years and that their findings are consistent with other research that demonstrates global warming.

The research team analyzed a 103 meter (338 foot) long ice core that was drilled out of Mount Logan at 5,340 meters (17,520 feet) above sea level from the north side of the mountain.

It sits within the heavily glaciated Saint Elias mountains, and according to the research team is "situated in a region of climatological importance."

Logan

This snow formation is the product of strong winds on Mount Logan. The weather that forms such shapes was recorded by three automated weather stations. (Photo courtesy Natural Resources Canada)
"It is located at the end of the major North Pacific storm track along the main atmospheric pathway by which water vapor enters northwestern Canada," the team wrote.

The study, Moore said, also offers confirmation of both higher surface temperatures and atmospheric warming that many climate change theories and models demand for evidence of climate change due to an increase in greenhouse gases.

Skeptics of global warming often use discrepancies between unchanging atmospheric temperatures and rising surface temperatures to cast doubt on theories of climate change.

Moore believes his team's findings correspond to the warming trend over North America and to two specific patterns of regional climate variability, known as climate modes.

These two modes are the Pacific North America (PNA) pattern and the Pacific Decadal Oscillation (PDO), and Moore offers them as possible explanations of the warming climate explored in his paper.

PNA associates high pressure and warming over the northwestern part of North America with low pressure and cooling over the Pacific Ocean.

PDO is an El Nino-like pattern of Pacific climate variability, with its warming in the Eastern Tropical Pacific Ocean. But unlike 18 month long El Nino changes, PDO events occur for periods of 20 to 30 years.

mountain

Mt. Logan is Canada's highest peak(Photo courtesy CalTech Alpine Club)
"We're seeing evidence that both of these climate modes have been intensifying," says Moore. "This is evidence that the atmosphere in the region has warmed up, and that it's doing it through an intensification of some natural modes of climate variability."

These intensified modes could affect regional winter weather patterns, Moore added and "Western Canada will continue to warm."

Moore also believes these findings will add fuel to the debate over humanity's responsibility for climate change, as previous research has shown that levels of atmospheric carbon dioxide also began to rise in Western Canada around 1850. Carbon dioxide is a major greenhouse gas linked to climate change.

In the present day, Moore said, the findings of atmospheric warming strengthen the argument that climate change is related to human activities.

Canada has been embroiled in a heated debate over whether to sign onto the Kyoto Protocol on global warming. If it ratifies the accord, Canada would be committed to cutting its emissions of six greehouse gases back six percent from its 1990 levels by 2012.

"We have to be serious about this," Moore said. "Kyoto is a start [but] I don't know if it's all we have to do. But, for our children and our children's children's sake, we need to deal with this because we've caused it."

Prime Minister Jean Chretien has pledged support for Kyoto, but politicians from mineral rich Western Canada have stirred up formidable opposition to ratification. Chretien has said that Parliament will vote on the issue before the members take their holiday break that begins in mid-December.

First presented at the 98th Association of American Geographers Annual Meeting in Los Angeles last March, the Mount Logan ice coring study was funded by the International Arctic Research Center in Fairbanks, Alaska, the Geological Survey of Canada, the National Institute of Polar Research in Tokyo and the Natural Sciences and Engineering Research Council of Canada. The research team included scientists from the University of Calgary and the PAGES International Project Office in Bern, Switzerland.

The paper can be found at http://www.nature.com/nature/links/021128/021128-5.asp

Natural Resources Canada Ice coring website: http://sts.gsc.nrcan.gc.ca/ice2001/maps.asp