Science goes to new heights
Thompson travels where few dare to retrieve ice core record
Posted June 27, 2008
It seems there’s little that Lonnie Thompson and his team of scientists and drillers haven’t tried in their quest to retrieve ice cores from high-altitude, tropical regions around the world.
A natural storyteller, Thompson spins tales of alpaca sacrifices at remote villages and abandoned hot air balloon adventures to the peak of Mount Kilimanjaro, scarcely needing journalistic prompts from his inquisitor. He’s well practiced at these sorts of interviews; his exploits a natural magnet for the armchair traveler.
He’s made more than 50 science expeditions to some 15 countries over the last 30-odd years. He solidified his reputation earlier this decade after warning that Kilimanjaro would permanently lose its frosty cap by 2020, if not earlier. Yet Thompson, a paleoglaciologist at Ohio State University’s Byrd Polar Research Center, views his celebrity with mixed feelings.
“It’s a blessing and a curse, and much of it is unwarranted because it’s really a team effort,” he says when asked about the fame that he’s achieved. But perhaps it’s not so unusual given his team’s mission: to recover the climatic history stored in the world’s vanishing ice fields between 30 degrees north and 30 degrees south latitude.
“I would never have guessed [it possible] 32 years ago if somebody had told me that I would still be looking at ice at my age. I’d say, ‘You’re crazy, because who’s going to fund it and how can it be important?’” muses Thompson, who turns 60 in July. “[Ice core science has] gone from being a boutique type of subject when I was a student to being center stage because of the potential impacts of sea level.”
Ice cores contain a wealth of information about past climate. Scientists can analyze the bubbles of gas trapped inside the ice to determine how much carbon dioxide, for instance, was in the atmosphere in the past. That’s how we know that current levels of CO2 — nearly 390 parts per million now — haven’t been this high in some 800,000 years, the extent of the current ice core record. Dust in the cores can reveal other information about climate, such as wind conditions.
Thompson, quoting Ernest Shackleton, whose ship was trapped and eventually crushed in sea ice during Antarctica’s Heroic Age of Exploration, notes, “‘What the ice gets, the ice keeps.’ … Ice will archive anything that gets trapped by it.”
And it’s the archive in the tropics that particularly interests Thompson, though his first polar fieldwork in the 1970s as a graduate student at OSU was to Antarctica. He found the flat, virtually featureless ice sheet uninspiring compared to the alpine areas he later explored.
“I really like the mountain ranges,” he explains. “You can look out from your drill site and you can see the Amazon Basin or the ocean. And where we work, you’re always working in a different culture.”
But it’s not really for the aesthetics that he and his colleagues regularly climb and drill into ice above 5,500 meters (more than 18,000 feet), where Thompson has reputedly spent more time above the so-called death zone than anyone on the planet. He observes that about 70 percent of the world’s 6.7 billion people (and counting) live just 30 degrees north and south of the equator.
“It’s an area where you need to understand natural climate variability, as well as potential human impacts on that,” he says. The ice, like Thompson, has many stories to tell.
Money well spent
Today, the ice core team led by Thompson and his colleague and wife, Ellen Mosley-Thompson, boasts state-of-the-art equipment at the Byrd Polar Research Center. The facilities include a Class 100 Clean Room, which contains less than 100 particles per cubic foot of air, where researchers, clad in all-white garb with white hoods like a nun’s habit, study ice samples. A cold storage facility, kept at about minus 40 degrees Celsius, houses about 7,000 meters of ice cores.
But times were hard when Thompson first proposed to the National Science Foundation (NSF) that it should support an ice coring expedition to the tropics 35 years ago. In collaboration with John Mercer — an OSU geologist who predicted in the 1970s that global warming would cause the ice shelves along the Antarctic Peninsula to disintegrate — Thompson approached one of the program managers at NSF’s Office of Polar Program (OPP).
The scientists wanted to take ice cores from the Quelccaya ice cap in the Peruvian Andes, to connect the ice data from the Antarctic and Arctic with something in the middle of the planet. Thompson and Mercer showed Jay Zwally at the NSF aerial photos of Quelccaya and outlined their plan for a reconnaissance mission. Zwally said he was intrigued, but Peru was out of the scope of the OPP.
The opportunity apparently lost, Thompson headed to Byrd Station in Antarctica during the 1973-74 summer season. Toward the end of his fieldwork, he received a telex from Zwally, who said he had funded all of his polar projects — and had $7,000 left.
As Thompson tells the story, Zwally asked, “What could you do on that tropical glacier for $7,000?” Thompson quickly responded, “‘I think we can get there.’ … The next summer, that’s what we did.”
Never mind that Thompson had little practical mountaineering experience (and has often said he’s not particularly fond of recreational hiking and climbing). Nor the fact that no one had tried to haul tons of ice coring equipment up towering mountains and return back with ice. But Thompson — standing on the summit of the Quelccaya ice cap in 1974 with Mercer, Chilean glaciologist Cedomir Marangunic, and Canadian mountaineer John Ricker — knew there was a unique treasure before him.
“Sure enough, it was clear there was a record, but getting that record was going to be a challenge because it was a two-day journey from the end of the nearest road to the margin of that ice field,” he recalls.
The exploratory trip led to a full-on expedition in 1979. But the team went in heavy, assuming drilling for core in the mountains would be like working on an ice sheet in Greenland or West Antarctica. Thompson and his team had hoped to transport the drill equipment and generator aboard a helicopter. But the machine had a maddening (and no doubt sickening) propensity to free-fall around 19,000 feet.
In the end, the researchers lowered themselves by ropes down the wall of the ice and sampled to the bottom of a 25-meter crevasse, returning with a perfectly preserved, 25-year record of El Niño, with the research later published in the journal Science. But the small samples were merely unsatisfying appetizers for Thompson.
“I was just really discouraged,” he says. “At that stage we were either going to have to give up or find a new way to drill.”
They did the latter. Working with Bruce Koci, an engineer at the University of Nebraska-Lincoln (whose name still comes up in just about any conversation about scientific drilling nearly two years since he passed away), they designed a solar-powered rig that was lighter than its predecessors. Good thing, because when Thompson and company returned to Peru in 1983, they had to haul themselves and their gear to the ice field.
“We had no porters, we had no one,” he says. “We carried everything to the summit, assembled the drill, carried the samples back down, prepared them, bottled them and shipped them out.”
But they did it, drilling two holes and pulling the first deep ice core from the tropics, which required cutting the 6,000 samples of ice by handsaw.
With those first samples, Thompson managed to build a 1,500-year record of tropical precipitation. The record revealed past El Niños, as well as dry periods, including evidence that that the Southern Hemisphere was cooled by the “Little Ice Age” recorded in Europe between 1500 and 1800, according to his biography published in Proceedings of the National Academy of Sciences of the United States of America in 2006.
“It all started on that $7,000 that was left over in 1974,” Thompson muses.
Civilization in ice
One of the intriguing things about working in the tropics is that you’re often working where civilization started, Thompson points out. It seems that weather and climate have always been a topic of conversation since time immemorial.
“You can see some of the [climatic] events that are recorded in the hieroglyphics on the tombs of the pharaohs in the ice itself,” Thompson explains excitedly. “That’s really striking that you can actually do those things.”
For example, in ice recovered from the Himalayas at some 23,000 feet, scientists can see the telltale signs of a monster monsoon that killed 700,000 people in central India in 1790 from increased dust and enriched oxygen isotopes. By tracking powerful storms like these back through time, researchers can determine how often they naturally occur — and whether human-induced climate change may be fiddling with natural variability.
In several recent ice cores drilled to the bedrock from the Naimona'nyi ice field in the western Tibetan Himalayas at about 6,100 meters, a more sobering fingerprint of human civilization helps date the records — thermonuclear tests from the 1950s and 1960s, particularly the U.S. Castle Bravo test in 1954 on Bikini Atoll, Marshall Islands.
“Those become timelines because we know exactly when the tests took place. We find that you can determine the accumulation rate for this area since 1963 or 1951,” Thompson says. “We’ve done that across China.”
And what they’re finding from those radioactive layers is that there’s been little if any net accumulation in the last half-century. The 58 glaciers on Naimona'nyi once covered an area ten times greater than today.
“They’re very important for water supplies in these areas, and that’s especially true in the dry season,” Thompson says. “That’s true whether you’re looking at glaciers in the Himalayas or down through the Andes. There’s a very direct link to people, to hydroelectric power production, to irrigation, to municipal water supplies.”
Indeed, Thompson talks about people as much as he does the science behind his work. A favorite story seems to be about an expedition to Sajama, Bolivia. At the base of the mountain where the team hoped to drill into the glacier on the summit was a village, whose permission they needed before beginning their work.
Thompson made a four-hour presentation of what the scientists proposed to do and why. But the village medicine woman considered the idea a bad omen. “She was absolutely sure that drilling these glaciers was going to anger the gods,” Thompson says.
To appease the gods — and maintain good relations with the villagers, always a priority — Thompson agreed to donate $500 to the library and to hire local people for labor (already in the plan). Additionally, the ice core team participated in the sacrifice of an alpaca to ask forgiveness of the gods. In the end, the gods were happy, the villagers were happy, and Thompson got his ice cores.
“All of the projects have a story, the challenge of how you get into these areas and how you get the cores out,” he says. “And all of them have stories about how incredibly supportive people are, in places where you have only met them, and they want to help you with your job. Without them, we wouldn’t have accomplished any of this.
“At the end of the day, you’re a guest.”
The story continues
The next chapter in the story goes back to the beginning, to Peru and the Quelccaya ice field, when a team from Byrd Polar returns to the region this summer. Thompson and team have made several trips to the glacier in the last 35 years, like a doctor making repeated house calls to a sick patient. In this case, the fever is causing the 160-meter-deep ice cap to melt away.
In the wake of the glacier’s retreat in 2002, the researchers found a perfectly preserved wetland plant. Carbon dating tests indicated the plant had been buried in the ice for about 5,200 years. That suggests that the climate had shifted suddenly to capture the plant and preserve it without killing it.
The date is significant because other abrupt changes in climate from around the world — such as the shift of the Sahara from a habitable region to a barren desert — also occurred around the same time. Thompson doesn’t know what happened to cause a plant to freeze in time, but one hypothesis is that fluctuations in solar output may be to blame.
Evidence shows that about 5,200 years ago, solar energy from the sun dropped sharply and then surged over a short period. This huge flux may have triggered unusually strong winters in Peru that suddenly buried plants in snow and droughts that laid waste to the Sahara.
The mystery is on the top of Thompson’s scientific agenda, particularly if human-induced climate change is bringing us closer to some sort of similar tipping point. Figure out what happened five millennia ago, and you may have a crystal ball into the future.
But time is running out; the clues in the mystery are disappearing. By the end of the century, Thompson says, most of the world’s tropical and subtropical ice will vanish.
“It will be gone. And history will be gone,” he says.
[Editor’s Note: For more about Thompson and his quest to recover ice cores from around the world, check out Mark Bowen’s book, “Thin Ice: Unlocking the Secrets of Climate in the World’s Highest Mountains.” The National Science Foundation provides funding for much of Thompson’s research.]
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