COLUMN ONE : Drilling for Frozen Secrets : Polar regions lure his colleagues, but an Ohio scientist braves tropical mountains for priceless climate records. Ancient snow yields worrisome data on global warming.
At a glance, there is nothing about Lonnie Thompson that evokes Indiana Jones.
There is nothing rakish, nothing reckless, nothing to suggest that in his soul, there is a kinship with the archeologist-adventurer of the silver screen.
Outside of Ohio State University’s venerable Mendenhall Laboratory and the corridors of the Byrd Polar Research Center’s new headquarters a couple of miles away, the slight, bespectacled scientist goes generally unrecognized and unnoticed.
But in a far-flung community of researchers trying to fathom the workings of the Earth’s climate system, Lonnie Thompson has become one of the huge figures of his generation, known for scrambling to the tops of glaciers unreachable by helicopter, for following professional mountaineers across crevasses and ice cliffs and for backpacking solar-powered drilling equipment to retrieve huge core samples of ice that fell as snowflakes hundreds of centuries ago.
The quest for his own Lost Ark has taken him from the top of the Peruvian Andes to wind-swept ice domes in China and Tibet. He has extracted priceless records of the Earth’s ancient climate, fossilized in icecaps on four continents, and become a prolific contributor to scientific journals that provide the underpinning for the worldwide debate over global warming.
While most of his colleagues in ice research have concentrated on huge projects in the polar regions, Thompson, his wife, Ellen Mosley-Thompson, and collaborators from China, Peru and the former Soviet Union have pursued a daunting, sometimes lonely, and, some have thought, quixotic agenda.
From the perpetually frozen wilderness, he has hauled out tons of ice cores on muleback, snowmobiles and man-hauled sleds, then trucked them across the hot and sandy Gobi Desert and through the shady South American rain forests on their way to a freezer at Ohio State.
Roughly the diameter of a baseball, the cores are extracted with hollow-bit drills turned by hand, solar power or generators run by snowmobile motors. Cut into three-foot sections, the cores are packed in specially designed cylinders and protected by insulated boxes and dry ice to keep them frozen on their long journey to Ohio.
Remarkably, Thompson has never lost a core, although he has come close. And for insurance, he melts one core at the drilling site, carefully labeling the samples. If some disaster destroyed the remaining cores he could at least analyze the chemistry of the water.
Once the cores arrive at the Byrd Center, band saws slice the priceless fossils of the Earth’s atmosphere into elegant slivers whose oxygen and hydrogen isotopes record passing ages, centuries and seasons. Within the molecules of air are contaminants left behind both by man and by nature--sulfur from great volcanic eruptions; cosmic debris from periodic disturbances on the sun; traces from the Dust Bowl of the 1930s; strontium, cesium and iodine from nuclear weapons explosions in the 1940s, ‘50s and ‘60s; lead; pesticides, and rising levels of carbon dioxide from the combustion of coal, oil, gas and wood.
But what most interests scientists around the world nowadays is the tale told by the oxygen in the ice cores.
Around the clock in a new Byrd Center laboratory, a computer-driven mass spectrometer measures the ratio of two different oxygen isotopes captured in the ice: oxygen-16, with eight neutrons and eight protons in its nucleus, and oxygen-18, which has two extra neutrons.
Ice rich in oxygen-16 is the legacy of snow that fell in relatively warm periods. Conversely, a higher ratio of oxygen-18 marks low-temperature precipitation.
Scientists have long recognized the value of ice as an archive. But the work of Thompson and other ice-core researchers assumed dramatic new urgency five years ago when French scientist Claude Lorius showed a direct correlation between temperatures, as revealed by the oxygen isotopes, and the atmosphere’s content of carbon dioxide.
Analysis of an ice core drilled by Soviet scientists in Antarctica showed that over a period of 160,000 years, temperature and carbon dioxide levels had risen and fallen in harmony.
It was the beginning of the great global warming debate.
Since 98% of the world’s 200,000 glaciers are located in the Earth’s polar regions, it is hardly surprising that this is where investigation of the ice record has focused.
But Thompson, parting company with most of his colleagues, has concentrated instead on high-altitude glaciers in the tropics and subtropics, reasoning that more important information is to be had there than from the much deeper cores in Greenland and Antarctica.
The heavier mountain snowfalls make it possible to retrieve records of higher resolution than in the deep cores of Greenland and Antarctica, where the climate is relatively arid and density of the ice compresses centuries into scant inches.
Whereas the deep polar cores spanning tens of thousands of years reveal the ebb and flow of the ice ages, Thompson’s glacier ice amounts to a more detailed record of the time man has inhabited the Earth.
Having grown up in Gassoway, W.Va., during a boom in the coal industry, Thompson studied geology at Marshall University in his home state, then moved on to Ohio State expecting to become a coal geologist. But not long after entering graduate school, he had his first chance to visit Antarctica, where he helped collect ice samples and analyze their dust content.
Thompson married his West Virginia sweetheart, Ellen Mosley, who was then working toward her own Ph.D. in geography, and they took up ice research in collaboration. Between his trips to glaciers over the succeeding years, she has taken part in landmark drilling projects in both Greenland and Antarctica.
Ten years before Lorius published his stunning paper on temperature and carbon dioxide, Thompson’s Ohio State team, backed by the National Science Foundation and the National Geographic Society, launched a long-term effort to recover a 1,000-year climate record from the Quelccaya icecap in Peru.
For a time, it appeared that his career as a big-time climate researcher would be brief.
When Peruvian Air Force helicopters tried to deliver his drilling equipment to the 18,600-foot Quelccaya summit in 1979, they encountered violent drafts in mountain passes, causing the aircraft to pitch and drop so violently that pilots found it impossible to land.
But Thompson was undaunted. Four years later, he took a truck convoy to the end of the road in the foothills, then proceeded for a day and a half on foot, with the help of professional mountaineers, 40 horses and 17 porters.
Finally, from a base camp on the edge of the glacier at 17,000 feet, the group hauled to the summit a solar-powered drill and 48 panels to convert sunlight into electricity. Each day thereafter, for nearly two months, the drilling party made the round trip to work through the daylight hours.
Using power from the sun, the crew drilled two cores, one 538 feet deep and going back 1,500 years. It was the first high-resolution ice core ever taken from the tropics, only a few hundred miles south of the Equator.
Among other things, the record revealed that the “Little Ice Age” that descended upon Europe from the 16th to the 19th centuries was not a local phenomenon but a result of atmospheric changes that influenced the Southern Hemisphere as well as the Northern.
The Quelccaya experience was also a lesson in the importance of preparation.
Since then, Thompson has carried out careful “dry runs” before every expedition, chiefly to assure that he can get his precious cores home safely to the freezer at Ohio State.
But there are still close calls. After one survey trip to the Dunde icecap in eastern Tibet in 1986, Thompson arrived in Los Angeles on a Friday night and watched in disbelief as the last of the baggage put aboard the plane in Beijing arrived without a sign of his ice cores.
Airline checks at every intermediate stop produced nothing. Finally, back at home in Columbus and desperate, Thompson made a direct call to the Beijing airport. An attendant on the other side of the world was persuaded to make a personal search for the boxes and found them still in the basement of the terminal--and still frozen. They eventually reached the Byrd Center intact.
The following year, he returned and drilled three cores reaching through the 460-foot-thick cap in Tibet. One was cut into thin sections in the field, with each section melted, labeled, and sealed in sample jars as insurance. A second went to his colleagues at the Lanzhou Institute of Glaciology and Geocryology in China, and the third brought back to Beijing as the sample core had been the year before.
Last year, Thompson returned to both China and Peru to make final preparations for drilling programs to be conducted in 1992 and 1993.
A two-month expedition to the Guliya icecap in western China was his second scouting trip to the summit of what is believed to be the highest--23,000 feet--and thickest--1,150 feet--lower latitude icecap in the world. It is also one of the most remote.
On the first trip to the site in 1990, Thompson’s 15-member party was on the road 17 days from Lanzhou to the fringe of the icecap in the western Kunlun Mountains. At night, they stopped at Chinese army bases, until their Land Rovers left the motor road and struck out cross-country for the last two days.
The preliminary trips have shown that recovering the ice record from Guliya next summer will be even more challenging than working on the Dunde icecap--where horses fell through the snow, forcing members of the scientific party to act as pack animals in hauling their equipment to the summit.
From the Guliya base camp at 18,400 feet, it is 15 miles and a farther climb of 4,600 feet to the summit.
Consequently, snowmobiles with specially designed carburetors for high altitudes will be used to travel between the drilling site and the base camp. And since the nearest medical facility will be more than five days away, the party will be outfitted with a medical kit, including equipment for dental surgery, and will carry portable hyperbaric chambers to deal with altitude sickness. The inflatable chamber eliminates the need to take along heavy tanks of oxygen. A member of the party stricken by effects of high altitude can be zipped inside and a pump increases the pressure to the equivalent of about 10,000 feet.
New techniques have been developed to keep a pair of 1,150-foot, 5-ton ice cores frozen for the five days it will take to reach a freezer in the town of Kashgar. Back-up vehicles will be taken along to prevent a potential mechanical breakdown from producing a disaster.
Two months after returning from western China last June, Thompson was back in the Andes on a second expedition to look over two new sites for drilling in 1993.
With scientists from the Peruvian Geophysical Institute and the National Meteorological and Hydrological Service, he left behind in the Andes the two highest satellite-linked weather stations on Earth, which are now providing continuous information on local conditions.
Thompson’s expeditions have created the world’s only archive of frozen climate records from the Earth’s lower latitudes and have led to regular publication in scientific journals.
One of his most provocative reports, co-authored with Ellen Mosley-Thompson and John Bolzan of the Byrd Institute, concluded that temperatures in central Asia have been warmer over the last 50 years than at any time since the last ice age.
Results from the Andes have been similar. After returning from a visit to Quelccaya icecap during last September’s survey expedition to Peru, Thompson said that he had found “the first clear evidence of unprecedented warming taking place in tropical South America in the last decade.”
In just eight years after his first successful Andes expedition, changes that were “large and disturbing” had taken place. A shallow ice core and 177 water samples are still being analyzed, but important differences were unmistakable. The largest glacier extending out of the icecap showed obvious signs of disintegration since his last visit, and just 18 meters beneath the summit where he drilled his 164-meter core in 1983, Thompson’s drill encountered a water table.
Early in 1992, he plans to publish a more complete description of the evidence of global warming in both China and Peru. His findings from analyses of the oxygen isotopes, he says, suggest that in both the Northern and Southern hemispheres “changes have taken place recently, and they have been of a fairly large magnitude.”
Then after testifying before a Senate committee, and trying out a new drill in Alaska, he will return to China in June.
In times past, scientists studied ice records by digging snow pits or sawing out blocks of ice.
Deep drilling hit the big time in 1966 when scientists from the Army’s Cold Regions Research and Engineering Laboratory took a 4,550-foot core from the Greenland ice sheet, drilling to the underlying bedrock at Camp Century in northern Greenland. Two years later, the same team penetrated the Antarctic ice sheet, drilling a core more than a mile long, and containing 50,000 years of climate history.
Subsequently, Soviet scientists took a core at their Vostok research station in Antarctica going back 160,000 years or more, providing the material for Lorius’ landmark analysis.
Next summer, U.S. and European scientists will return for their third season working at neighboring drilling sites atop the Greenland ice sheet, seeking to obtain 10,000-foot cores to bedrock. The U.S. team, led by University of New Hampshire scientist Paul Mayewski, who was completing his Ph.D. at Ohio State when Thompson arrived at the graduate school, was at 4,953 feet at the end of its second summer of drilling.
Once the Greenland core is finished, the National Science Foundation plans to move the drill, developed by its Polar Ice Coring Office at the University of Alaska, to Antarctica to work on the west Antarctic ice sheet.
There is evidence that the vast sheet is diminishing and prophets of doom have noted that sea-levels would rise some 20 feet and swamp many of the world’s major cities if it broke up.
It is believed that the noted shrinkage is due to local conditions rather than global warming, but American scientists are anxious to know more about the age, and, therefore, the stability, of the great expanse of ice.
Thompson, nevertheless, contends that the U.S. research program has its priorities out of order.
“It is truly amazing how many drilling programs we have had and how much we know about the polar regions,” he says, “but the human population lives in the lower latitudes, and in the lower latitudes there are a number of excellent sites for drilling, where we can investigate important climate phenomena such as the monsoons and el nino, which have no great impact on the polar regions.
“I did my Ph.D. thesis on the Camp Century and Byrd cores, and we still do work in the polar regions, but early on it became obvious to me that we weren’t getting any closer to understanding the climate system. We need to know how the system works and it seemed that one of the things that needed to be done was to look at annual resolution climate records from the tropics, the subtropics and the polar regions over a period of time.
“At some of these tropical sites, if we don’t recover the records soon, they are not going to be available to mankind,” he says. “The evidence is very clear in the tropics and the subtropics that warming is taking place. Many of the glaciers in the tropics have disappeared in the last century, and the rate of change seems to be increasing.
“Whether this is the greenhouse effect or just natural variability in the system, you can still argue.”
