Thompson leads expedition to Alaskan glaciers

By Earle Holland, Research Communications

Glaciologist Lonnie Thompson hopes that once his latest expedition ends in early summer, he will have one of the so-far missing pieces to the global climate change puzzle -- a record of ancient weather trapped inside ice from Alaskan glaciers that could date back thousands of years.

Thompson, professor of geological sciences at Ohio State, is leading the expedition -- his 45th -- to a rugged and remote region of the Wrangell-St. Elias Mountain range on the U.S.-Canadian border. There, in an ice-filled saddle 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 during the last quarter-century. The cores they have returned to Ohio State's Byrd Polar Research Center paint a picture of climate across the millennia, with the oldest dating back 600,000 years.

Lonnie Thompson, professor of geological sciences at Ohio State, is leading an expedition -- his 45th -- to a rugged and remote region of the Wrangell-St. Elias Mountain range on the U.S.-Canadian border.   File photo

From these cores, Thompson and his wife and research partner, Ellen Mosley-Thompson, a professor of geography, have built a history of ancient climate around the world over the centuries. From this history, they should 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 .6 degrees Celsius (1.08 degrees Fahrenheit) during the last century," Thompson said, "but in Alaska and in parts of Russia and Canada, researchers have seen an increase of nearly 2 degrees Celsius (3.6 degrees Fahrenheit) in just the last 30 years.

"We know that some of the largest glaciers in the region have retreated more than four kilometers (2.73 miles) in just the last two decades," he said. "These 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 stratigraphic layering of annual snowfall, offer the best key to understanding what those changes were, how serious they were and what caused them. That is the reason Thompson is now turning to Alaska.

Thompson's expedition should have arrived in Anchorage on April 30 and from there, the team is making its way to a jumping-off point at the tiny May Creek Airport inside of the vast Wrangell-St. Elias National Park and preserve and about 30 miles east of the target destination.

From there, the expedition members will use an A-Star 350, high-altitude helicopter to cross the mountains to the Klutlan Glacier, where they will establish a base camp at 10,500 feet. After a few days acclimatization, team members will be ferried up to the col, or saddle between Mount Churchill, a 15,638-foot (4,766-meter) stratovolcano, and Mount Bona, its 16,420-foot (5,005-meter) neighbor.

The six tons of equipment for the six-week expedition was trucked from Columbus to Chitna, Alaska. From there, the researchers will use a super-charged Twin Otter aircraft to carry the equipment to the drill site.

Once the drill site is established at 14,500 feet (4,300 meters), Thompson and his team will attempt to drill through the ice cap to bedrock to retrieve the entire climate record preserved there.

Unfortunately, no one knows how deep the ice is at the col, so the expedition will have to use radar to gauge the depth of the ice field. They're carrying equipment that would let them drill as deep as 700 meters (2,300 feet), although Thompson thinks the distance will be much shorter.

"I believe that there is a natural limit within mountain glaciers as to how thick ice on top of a mountain range can get," he explained. "At most sites around the world, such ice fields are between 130 and 160 meters (426 to 525 feet) thick, although we have retrieved cores at one site that reached 308 meters (1,010 feet)."

The geologic history of the region will probably play an important role in this expedition. Mount Churchill experienced two major eruptions -- each more powerful than the 1980 eruption of Mount St. Helens in Washington -- in 700 A.D. and in 65 A.D. These blasts deposited thick layers of volcanic ash, or tephra, over hundreds of thousands of square kilometers in the region, including the ice on the mountain at the time. Thompson believes that those layers are perfectly preserved within the ice.

The tephra layers, however, will pose a problem for the sophisticated drill used to core the ice, so the team had to design a new drill bit assembly capable of drilling through ash that may be as much as a meter thick.

"We've prepared and tested five new drill systems on campus in anticipation of what we might face on Bona-Churchill," Thompson said. "We want to be prepared for every contingency since this expedition, aside from its importance on its own, may serve as a warm-up to future projects in areas as remote as the Antarctic Peninsula."

The Office of Polar Programs in the National Science Foundation supports the project.

Researcher wins Heineken Prize

An Ohio State researcher who has become famous for his work in using ice cores from drilled remote, mountaintop glaciers to unravel global climate histories for thousands of years is this year's winner of a prestigious international science prize.

Lonnie G. Thompson, professor of geological sciences and researcher with the Byrd Polar Research Center, will receive the 2002 Dr. A.H. Heineken Prize for Environmental Sciences.

The prize, one of five awarded each year and given by the Royal Netherlands Academy of Arts and Sciences, comes with a cash award of $150,000. Thompson will receive his award in September during ceremonies in Amsterdam.

In announcing the award, the Academy cited Thompson's "pioneering work in research into ice cores in the polar regions and in the tropics," adding that the work "ultimately makes it possible to assess the effects of human beings on the Earth's climate, something which has been a source of heated debate among researchers for many years."

"This is an extraordinary award, and one of the most important in a long line of recognitions that have come to Dr. Thompson and his colleagues in recent months which acknowledge the profound relevance this research has for the entire world," said Edward J. Ray, executive vice president and provost.

"This work sets an exceptionally high standard for research that is both grounded in basic research and of great significance, in a practical sense, in the lives of all peoples. We are immensely proud of what he and his team have accomplished."

Thompson has spent more than two decades drilling ice cores from mountaintop ice caps throughout at least seven countries and returning them to the University for analysis. Those cores contain stratigraphic records of climate that can extend back tens of thousands of years. Understanding the pattern of ancient climate can give us insight into the changes that are occurring throughout the world today.

Thompson shocked the public and scientific community alike last year when he announced that the analysis of ice cores from high mountain glaciers in Africa and Peru showed melting at an alarming rate -- one that would lead to the loss of those ice fields within 15 years.

"This is exceptional research accomplished by exceptional scientists in extraordinary conditions," explained C. Bradley Moore, vice president for research.

"Lonnie's research group has grown from early struggles for acceptance within the glaciological community to becoming one of the premier scientific programs in the world investigating the questions surrounding global warming."

In the past year, Thompson was named one of America's Best Scientists by Time magazine and the Cable News Network, placing him in a prestigious group numbering less than two dozen.

Last month, he and his wife and research partner, Ellen Mosley-Thompson, a professor of geography at Ohio State, were selected to receive the Common Wealth Award of Distinguished Service for Science and Invention.

The award, one of five such awards given annually, carries with it a cash prize of $50,000. Other recipients included actress Julie Andrews and Fred Rogers, creator of the children's television program Mr. Rogers' Neighborhood. Previous award winners have included oceanographer Robert D. Ballard, heart surgeon Michael DeBakey and J. Craig Venter, founder of Celera Genomics.

Black raspberries a potentially powerful agent in fight against colon cancer

There is a potentially powerful biological weapon for health -- a mix of compounds suspected of thwarting colon cancer -- hiding deep inside the juicy sweetness of a black raspberry. And if it can be harnessed, it could play a major role in preventing the second-leading cause of cancer deaths in the United States.

In a recent study, rats that were injected with a cancer-causing agent and then fed a berry-rich diet had 80 percent fewer malignant tumors compared to rats that had no berries in their diet.

For years, scientists have touted the health benefits of eating fruits and vegetables. They're only now starting to gain an understanding of what compounds give certain foods a healthful edge. Black raspberries are rich in several substances thought to have cancer-preventing properties, said Gary Stoner, a study co-author and a professor of public health at Ohio State. Stoner is also a researcher at the University's Comprehensive Cancer Center.

Such substances are called antioxidants. The researchers also compared the antioxidant activity of black raspberries to that of blueberries and strawberries, two fruits with suspected chemopreventive effects. Black raspberries prevailed in the comparison by as much as 40 percent.

"We were surprised by how much difference there was between the antioxidant activity of the raspberries vs. the other fruits," Stoner said.

The research appears in the current issue of the journal Nutrition and Cancer.

Rats were injected with azoxymethane (AOM), a carcinogen that causes colon tumors. After two weeks of exposure to AOM, the animals were placed into four groups and fed diets mixed with 0, 2.5 percent, 5 percent or 10 percent freeze-dried black raspberries. Two additional groups of rats, which did not receive AOM, served as controls. The two latter groups were fed a diet containing 0 or 5 percent freeze-dried black raspberries, respectively.

Nine weeks after the final injection of AOM, researchers looked for the development of tiny lesions in the colon called aberrant crypt foci (ACF). Although ACF rarely occur in humans, the lesions can develop into polyps in rats. In humans, polyps are benign masses of tissue which, if left untreated, could develop into malignant tumors.

Every rat injected with the carcinogen AOM developed the ACF lesions. While most of these lesions go away on their own, Stoner said, some may eventually develop into malignant tumors. In rats fed diets supplemented with black raspberries, the number of malignant tumors seemed to correspond with the amount of freeze-dried berries fed to a rat Ñ the more berries a rat ate, the fewer tumors it had.

At the end of the study, the prevalence of adenocarcinomas -- or malignant tumors -- was reduced by 80 percent in the rats that ate the most black raspberries in their diets.

"That's a much higher reduction than I thought we'd see," Stoner said.

Adenocarcinomas were reduced by 28 percent and 35 percent, respectively, in the groups eating diets of 2.5 percent and 5 percent black raspberries. This reduction is based on the average number of tumors found in rats that had been injected with AOM and fed a berry-free diet.

The tumors were smaller in the rats that ate freeze-dried berries -- diets of 2.5 percent, 5 percent and 10 percent yielded reductions in tumor size of 28 percent, 42 percent and 75 percent, respectively, when compared to the animals not fed the berries.

The researchers also measured urinary levels of 8-OHdG -- a compound that is related to the degree of oxidative damage in the body. The process of oxidation produces free radicals, which can damage cells as well as genetic material. Free radicals are thought to play a role in the onset of cancer.

Berries reduced the level of 8-OHdG in the urine by 73 percent, 81 percent and 83 percent in the 2.5 percent, 5 percent and 10 percent berry diets, respectively.

"This suggests that berries bind up a good portion of free radicals, preventing them from causing damage in the body," Stoner said.

In addition to measuring the levels of some of these chemopreventive compounds, Stoner and his colleagues compared the antioxidant activity of the black raspberries to that of strawberries and blueberries. Previous studies suggested that these two fruits had antioxidant activity superior to that of other fruits commonly eaten in the United States, but researchers had not studied black raspberries.

Using a device that measured each fruit's ability to absorb free radicals, the researchers found that black raspberries topped the charts: These berries exhibited 11 percent more antioxidant activity than blueberries and 40 percent more than strawberries.

One reason for the raspberries' seemingly stellar health advantage may be their richness in compounds such as anthocyanins, which give berries their almost-black pigment; phenols, such as ellagic, coumaric and ferulic acid; calcium; and vitamins such as A, C, E and folic acid. All of these substances are known chemopreventive agents, Stoner said.

Fresh black raspberries are undoubtedly beneficial, but they are also expensive and can be hard to come by. Freeze-dried berries have as much nutritional content as fresh berries do, but the freeze-dried version isn't readily available to consumers, Stoner said. He tells people to hold off on getting discouraged, though.

"The results of this study would translate in humans to eating two large bowls -- or four cups -- of fresh black raspberries each day," he said. "That may seem a bit extreme. People need to know that these animals are given whopping doses of a carcinogen. It's conceivable that a much lower dose would be effective in humans."

It's also good to keep in mind that the National Cancer Institute continues to recommend four to six helpings of fruits and vegetables each day. "We're just suggesting that people make one of those helpings berries," Stoner said.

The research was supported in part by a grant from the Ohio Department of Agriculture.

Stoner conducted the research with Ashok Gupta, Ronald Nines, Laura Kresty, Wendy Frankel, Suzy Habib, Krista La Perle and Professor of Food Science and Nutrition Steven Schwartz, all with Ohio State; Gabriel Harris of the National Institute of Occupational Safety and Health in Morgantown, W. Va.; and Daniel Gallaher of the University of Minnesota, Twin Cities.

Glenn Institute receives Kellogg grant

The John Glenn Institute for Public Service and Public Policy has received a $50,000 grant from the W.K. Kellogg Foundation to enhance community/school relationships in the field of service learning. The funding builds upon a grant the institute received from Kellogg last year, as well as on the National Commission on Service-Learning, which Sen. John Glenn chaired and the institute co-sponsored with the Kellogg Foundation.

Service learning is a teaching technique that combines community service with classroom academics. Because of the success of service learning in improving both academic achievement and civic engagement, the National Commission has recommended that every student participate in a high-quality service learning project every year from kindergarten through grade 12. The commission and Glenn Institute are working now to expand service learning opportunities for all students.

Many national service organizations, such as the Lions Club, already support service learning because of its educational advantages. This grant will allow the Glenn Institute to build on that support by convening the directors of those national organizations for a daylong dialogue with school administrators about service learning. The institute hopes that this exchange will result in increased funding for service learning projects as well as long-term partnerships between service organizations and local school districts.

next page...