| OTTAWA,
Canada (Reuters) -- A team of Canadian scientists will launch
an international expedition next week to extract a long needle
of ice from a giant haystack of a mountain that will reveal
the secrets of 10,000 years of climate change.
The
Geological Survey of Canada said on Thursday its ice-core
expedition will see scientists climb Mount Logan -- Canada's
highest peak at 5,959 meters (19,550 feet) and the second
highest in North America -- in the isolated St. Elias ice
fields that straddle the border of the Yukon Territory and
Alaska.
"What
we're going for on this expedition is the big story, the
long story, the 10,000-year record," said Don Lemmen,
chief of environmental geology at Natural Resources Canada.
Two
Canadian scientists will battle snow storms and bone-chilling
temperatures to scale the snow-covered peak -- also the
world's largest massif -- in May and June.
They
will drill into it sideways near its top until they reach
bedrock to pull out a tube of ice measuring 225 meters (738
ft) -- the longest sample yet taken from Logan and the first
time such an extensive study will be conducted on a geographical
feature located so near the Pacific Ocean.
"The
real issue that we're trying to address is: how does the
climate vary naturally, and what influence human beings
have now and into the future?" Lemmen said.
The
tube will be cut into one-meter slices that will be cached
on the frozen mountain until next spring, when they will
be brought down and carried by refrigerated trucks and airplanes
to laboratories in Ottawa.
Scientists
from the United States, Japan and Sweden are participating
in the study and will look at snow samples as well as pollen,
aerosols and volcanic ash deposited onto the massif from
the atmosphere over thousands of years.
Climate
change, in particular global warming, has fast become a
huge environmental issue as worries grow over the effects
of chemicals used by humans on the earth's atmosphere.
Mount
Logan constitutes the perfect ice museum because its distance
from human habitation has saved it from exposure to civilization,
save for the handful of climbers who try to reach its summit
each summer.
"Glaciers
are a really unique archive," Lemmen said.
But
even in summertime the conditions are inhospitable to say
the least, with frequent storms and nighttime temperatures
dropping to -30 C (-22 F).
The
base camp at 2,800 meters (9,186 ft), and two camps for
scientists at higher elevations, will be far from where
weary mountain climbers have trudged to reach the peak of
the mountain -- so deep in the ice field they can be seen
only from an airplane of reached by expert mountaineers.
Scientists
have previously taken ice cores from Greenland and Canada's
eastern Arctic, but have yet to study climate change on
the Pacific Ocean side of North America -- from where many
North American weather influences emerge.
The
last time an ice core was taken from Logan was in 1980,
but technology has improved to allow scientists to extract
as large a sample as the one planned.
"Logan's
a pretty Pacific creature," said David Fisher, principal
investigator on the expedition. "It's the only place
that will see a good Pacific record."
The
possibility exists that volcanic ash could be found from
eruptions in 4000 BC in Alaska's Aleutian range, or that
airborne pollen from Siberia, China or Japan may also be
detected, scientists said.
Summit
leader Mike Dumuth, who has scaled Mount Logan several times,
said the expedition will provide many challenges -- thin
high-altitude air, low temperatures and increased ultraviolet
radiation at the higher elevation.
"You're
freezing your feet but you're getting sunburned at the same
time," Dumuth said.
Mount
Logan became the center of controversy when the ruling Liberal
party announced it would change the name of the peak, named
after geologist Sir William Logan, to Pierre Trudeau after
the Liberal prime minister who died last October.
The
Liberals quietly dropped the plan because of public opposition
to the name-change.
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