Deciphering the ice
Scientist drills into tropical glaciers
for clues to Earth's climate changes
(CNN) -- In the Ernest Hemingway short story "The Snows of Kilimanjaro," an image of the highest point in Africa is the last vision of a dying man. The story piqued the public's interest in the snow-capped mountain near the equator.
Decades after Hemingway first wrote about it, the ice field on Kilimanjaro, and other glaciers on some of the world's highest peaks, have their own stories to tell.
Scientist Lonnie Thompson is the translator, deciphering the cryptic messages in the ice to tell the history of the world's changing climate.
"I believe ice is our best archive of the history of the Earth's climate," he says. "Understanding how the climate system works and has worked in the natural system is absolutely essential for any prediction of what's going to happen to the climate in the future."
Thompson is a glaciologist at Ohio State University's Byrd Polar Research Center. His research focuses on searching glacial ice for clues to global warming, and he uses new technologies in the emerging science of paleoclimatology.
"Paleoclimatology is the study of climatology, the climate of the Earth. This is not the weather, the day-to-day, month-to-month variation," he said.
Glacial ice is melting
Thompson's research is finding that the Earth is heating up and the warming is taking its toll on the ice. The glaciers -- including the snows of Kilimanjaro -- are retreating. And when they melt, the archive is gone.
"Something that's really striking about the late 20th century is the scale at which the retreat has taken place," Thompson said.
Thompson and his fellow researchers use specially designed drills to bore thousands of feet into the ice and bring back ice core samples from the glaciers. The drill brings up ice 1 meter at a time.
Thompson said the amount of ice the drill retrieves depends on variables like temperature. On average, he said, the drill penetrates between 25 and 30 meters of ice a day.
The deeper the drill goes, the further back the ice goes in time. Thompson's deepest core dates back more than 700,000 years. It is similar to the rings in a tree, but whereas tree rings only measure the age of a tree, the ice records what was going on around it.
"The beauty of ice though is that it's a physical parameter. It's not biological," Thompson said. "It records what's going on in the ... Earth's system. But it is layered just like a tree; only it'll go back thousands and thousands of years."
To understand the current human impact on climate, scientists must know how the system worked for thousands of years before people entered the equation. To do so, researchers have probed the polar regions, home to 98 percent of the world's glaciers.
Early in his career, Thompson parted company with his scientific colleagues, arguing that by studying polar ice only they were missing an important part of the climate puzzle. He decided to focus on the glaciers in the highest altitudes of the tropics.
"When you look at the Earth, 50 percent of the surface of this planet lies between 30 (degrees) north (latitude) and 30 south in the tropics," he said. "This is where the energy comes in to drive the climate system."
The tropical region also is where major weather systems develop. It's the origin of the El Niño phenomenon, the place where monsoon rains occur and where hurricanes and cyclones build their strength.
The tropics is also where 70 percent of the human population lives, and where 80 percent of the new babies are being born.
The hottest part of the globe, Thompson said, is crucial to understanding global warming.
But to find ice in the tropics, you have to climb pretty high. Thompson has led some 40 expeditions to the Himalayas, Kilimanjaro and the Andes in South America.
To do the work, he assembles a team, hauling an average of six tons of equipment to a mountaintop. The equipment is sometimes carried by yaks, but most often, it is ferried up on the heads and backs of local porters. The drill itself is solar-powered so the expedition teams don't have to carry generators and fuel up a mountain.
Besides the physical challenges, Thompson also faces logistical hardships. He must deal with governments and local villages to secure permits and hire porters and mountaineers, which can be especially tough in developing nations.
A recent expedition to Kilimanjaro in Tanzania required 25 different permits. Ice cores from a China expedition got lost in customs but were found before they melted.
"One thing I've learned from Lonnie is ... if you're determined enough you can really do anything," said research associate Mary Davis, who has taken part in several of Thompson's expeditions. "I've seen him go off against impossible situations. I think most people would just throw up their hands and say, 'OK, I've done my best. Let's quit and go home.'
"And ... he hits that wall, and he knocks it down. And I think it had a lot to do with Lonnie's sheer determination and will to get it done, plus his gift for diplomacy dealing with people."
Once the team has traveled to an expedition site, the challenges keep coming, including equipment maneuvers over crevasses, the danger of avalanches, bone-chilling temperatures, thin air and frequent windstorms.
A storm once blew Thompson's tent from its moorings and nearly sent him off a cliff. Thompson's team has also set a record for staying the longest at the highest altitude, three weeks working above 23,000 feet elevation in Asia.
"It gets easier after you've done it a couple of times because you're acclimatized," he said.
A family affair
Thompson said all the effort is worth it during the exciting moments of discovery. Sometimes things are immediately visible in the ice. But most of the secrets in the ice won't be revealed until they're analyzed in the lab. To do that, the team has to get ice cores back down before they melt.
On average, six tons of equipment go up, but 10 tons come back down when you add four tons of ice samples. Each core sample is carried by hand in an insulated box. Thompson has even experimented with a hot air balloon to float the cores down to the nearest freezer.
The insulation will keep the cores frozen long enough for the plane trip back to Ohio. Once the ice arrives at the labs, a team of seven scientists gets to work on the analysis.
Lonnie's wife, Ellen Mosely-Thompson, is a key player on the team.
"I guess from about 1974 until 1983 it was really just the two of us building the group," she said.
The pair came to Ohio State after meeting in college in West Virginia. Being from a coal-mining region, Thompson went to Columbus to study coal geology but soon took an opening as a research associate on polar ice cores.
Mosely-Thompson had an interest in physical geography, and their careers started to converge. They divided up the globe between the two of them. "I don't work in the tropics, and Lonnie doesn't really routinely work in the polar regions," she said.
Thompson also said they were raising a daughter and wanted at least one parent at home at all times. "It worked out very nicely. It's certainly been a team effort," he said.
Mosely-Thompson said the two discuss few things outside of their own lives.
"Yes, we're very focused unfortunately," she said. "I would say the bulk of our conversation is on three topics: our work, our daughter and our dog."
Their daughter is now grown, but they've decided the partnership works best when they each lead their own projects.
"And so we kind of just developed a division of labor so to speak. And I kind of can picture myself as more of the detailed person," she said.
'A frozen history of the Earth'
Their work together has helped to create an impressive archive that Thompson calls a library of the Earth's climate history. Thousands of ice core samples are stored on shelves in a deep freeze at the research center's labs.
"This is history. It's a frozen history of the Earth," he said.
As researchers study the data in this library, they can reach back in time to mark the temperature over millennia. One marker of temperature is the presence of different types of oxygen atoms -- called isotopes -- trapped in the ice.
Water with the oxygen-18 isotope freezes at a higher temperature than water with the normal oxygen-16 atom. So higher amounts of oxygen-18 show a warmer year for that section of ice.
A recent core sample from the Dasuopu glacier in Tibet reveals the last 50 years to be the warmest of the last 9,000.
"Lonnie's work is a very important piece of the puzzle to show how the recent warming is actually occurring," said Kevin Trenberth, the head of the climate analysis section of the National Center for Atmospheric Research.
Trenberth uses the data from the tropical ice cores to help determine future climate change.
"They often indicate things like El Niños, and how the El Niños have varied in the past is a very important issue for understanding many of the regional climate changes throughout the tropics, and subtropics especially, but even around the world," he said, adding that the "tropical glaciers give us that record much better than anything else that we've got at the moment."
Kilimanjaro ice could melt by 2015
Thompson said glaciers are wonderful to study because they have no political agenda. They only respond to changes in the climate system.
"The Earth is warming ... there's no doubt about that," he said. "And the glaciers are responding to that. How we respond to this observation ... (has) very important implications to the future and particularly for the world as a whole."
But Thompson is in a race against time to gather samples from tropical glaciers before they melt.
"Well if we don't get them now, then they will be lost to us forever," Trenberth said, "and there's no replacement for the kind of information which they bring. There's no other source."
Thompson has found that the ice is melting at a rapid rate at some sites. At the Quelccaya glacier in Peru, a lake now exists that was not there in 1974 when Thompson first visited. In some areas, the ice is retreating about a foot a day, he said.
"Those glaciers -- they're really a bank account," he said. "They have stored water resources over thousands of years."
But more than just scientific data will be lost. Thompson said it won't be long before the only way to see the snows of Kilimanjaro is at the movies.
"In 1912, there was 12.1 square kilometers of ice on the mountain," Thompson said. "When we photographed the mountain in February of 2000, we were down to 2.2 square kilometers. If you look at the area of decrease, it's linear. And you just project that into the future, sometime around 2015, the ice will disappear off Kilimanjaro."
A legacy frozen in time
If that comes to pass, if anyone wants to study the ice of Kilimanjaro, they will have to travel to Thompson's lab to examine the ice core sample he has taken from the mountain.
Thompson also worries about the more immediate human consequences of losing ice in these areas. Tourism at Mount Kilimanjaro is one of Tanzania's key sources of revenue.
"People go there to see the snow and the ice on this mountain," he said. "It's already impacting tourism in Switzerland, where the glaciers have retreated and their tourist industry is down by about 10 percent."
Thompson finds solace in knowing that the archive of ice will be in his labs as new technologies emerge.
Though he doesn't have plans to slow down any time soon, Thompson, 53, knows getting older means he won't always be able to make these expeditions. But whenever he hangs up his boots and parka, he need only open a freezer door to see his legacy frozen in time.
"If there's a message that I would send to other young scientists coming along, (it) is to study nature, not books," he said. "It's the real world that we ultimately have to understand and let the records tell you what actually took place."
For Thompson, there is no textbook to becoming America's best. He's done it by reading nature carefully, translating the complex secrets embedded in the ice.