Looking for Climate Clues in Alaska

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.

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