Glaciologist Lonnie Thompson, of Ohio State University,
wants to read the record of ancient weather trapped inside
ice from Alaskan glaciers that date back thousands of years.
He?s going on his 44th expedition to the remote region of the
Wrangell-St. Elias Mountain range on the U.S.-Canadian
Border. There, in an ice-filled area between two mountain
peaks, he and a team of researchers will use a solar-powered
drill to pierce the ice cap and retrieve these records.
Thompson and his research team have undertaken similar
missions to ice fields and glaciers to Peru, Bolivia, Antarctica,
Greenland, Kurgyzstan, China, Africa and the Russian Arctic.
They?ve returned the cores they?ve drilled to Ohio?s State?s
Byrd Polar Research Center. They reveal the details of
climate across the millennia, with the oldest information
dating back 600,000 years.
From these cores, Thompson and his wife Ellen Moseley-
Thompson, a professor of geography, have built a history of
ancient climate around the world over the centuries. They
want to be able to determine if recent evidence of global
warming is just part of a natural cycle or, as they suspect, it
is evidence that human activity has altered the planet's
weather system.
"The average surface temperature across the planet has risen
by about 1.08 degrees F during the last century," Thompson
says, "but in Alaska and in parts of Russia and Canada,
researchers have seen an increase of nearly 3.6 degrees F in
just the last 30 years. We know that some of the largest
glaciers in the region have retreated more than 2.73 miles in
just the last two decades. These are large bodies of ice are
remarkably sensitive to climate change."
While the retreat of glaciers is an obvious indicator that
something about the climate has changed, the ice cores,
with their layering of annual snowfall, offer the best key to
understanding what those changes were, how serious they
were and what caused them.
Thompson doesn?t know how far down they will have to drill
into the ice, but they?ll take equipment to Alaska that will
allow them to drill as deep as 2,300 feet. The geologic
history of the region will probably play an important role in
this expedition. In 700 and 65 AD, the area experienced two
major eruptions, each more powerful than the 1980 eruption
of Mt. St. Helens in Washington. These blasts deposited thick
layers of volcanic ash over hundreds of thousands of square
miles in the region. Thompson believes that those layers are
perfectly preserved within the ice.
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Another group of scientists has ridden snowmobiles more
than 700 miles across Alaska to find clues to global warming.
Every few miles, members of the SnowSTAR 2002 expedition
hopped off their snowmobiles and started digging snow pits
and conducting experiments. By the end of their journey last
week, the six-member team had dug about 400 pits between
Nome, Alaska, and Barrow, the northernmost city in North
America.
SnowSTAR 2002 set out March 22 from Nome towing
scientific and survival gear in nine sleds. The expedition
headed northeast, stopping at several villages before
crossing the Brooks Range, which separates subarctic Alaska
from the Arctic. At each stop, they dug shallow snow pits,
counted snow layers and took samples of snow to test for
levels of calcium, magnesium and various isotopes. The snow
also was examined for grain size, water content, strength
and translucency.
"The snow is making a very major role in how energy is
being exchanged between the atmosphere and the earth,"
says Matthew Sturm, expedition leader and scientist with the
Army's Cold Regions Research and Engineering Laboratory in
Fairbanks. "We have got to understand that if we are going
to understand Arctic climate change."
The expedition is part of a five-year, $1 million National
Science Foundation study on global warming. The study is
being done in the Arctic because the effects of global
warming are expected to show up there first and be most
exaggerated, says Michael T. Ledbetter, director of the
National Science Foundation?s Arctic System Science
Program in Arlington, Va.
Scientists hope the data obtained from this trek will be
useful for developing models for climate change. In the past
30 years, temperatures in Arctic Alaska have increased an
average of 2 to 4 degrees. The increase is enough to have
caused the permafrost - ground that normally stays frozen
year-round - to thaw in some parts of Alaska's Interior near
Fairbanks and further south near Anchorage.
The warming is causing the area to switch from one in which
carbon dioxide is absorbed and stored in frozen soils, to one
where carbon dioxide is being released into the atmosphere.
Aerial photos taken in 1999 and 2000 indicate that the
amount of vegetation in northern Alaska has increased in the
past 50 years and the tree line is moving north. Areas that
were once mostly lichen-covered tundra are now sprouting
trees and shrubs, because with higher temperatures and
more snow melt, shrubs are getting more nutrients and
growing larger, blocking the sun from reaching the lichen.
To learn what our future weather is likely to be and why,
read ?The Coming Global Superstorm? by Art Bell & Whitley
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