Antarctica is a vast climate-science laboratory. For millennia, each new storm here captured the dust and chemicals brought by high-altitude winds from warmer latitudes and concentrated them at the bottom of the earth as the snow piled up and compressed into ice. Gradually, the snow pack became a periodic table of elements and temperatures 11,365 feet deep. "Because it never melts, they are perfectly preserved," says hydrologist Ray Banta from the Desert Research Institute, who is analyzing the ice. Dr. Taylor and his colleagues chose the remote drilling site in part because the snow and ice here accumulates about 10 times faster than most places in Antarctica. That means the annual layers are thicker and easier to tell apart. Winter snowflakes are usually smaller and more densely packed, easily distinguished from the looser summer snow. By testing differences in acidity and electrical conductivity, researchers can also distinguish one year from the next. Ice cores excavated elsewhere before in Antarctica have tapped into even more ancient ice. But none of these ice cores offered such well-defined annual layers as those here at the WAIS Divide. Scientists here expect to harvest extremely detailed data for each of the past 40,000 years, plus another 60,000 years of data using both proven and experimental measuring techniques. Modern records of carbon dioxide levels go back a mere 50 years, and reliable temperature readings cover only the last 150 years or so. By measuring oxygen isotopes, the scientists can track the rise and fall of seasonal temperatures. Sulfates and ash reveal volcanic eruptions, which can help determine the age of the ice. Light isotopes of carbon in the ice can suggest the extent of vegetation elsewhere in the world. Calcium and a rare earth element called cerium hint at the extent of the world's deserts, while sodium is a measure of ocean storminess and sea spray. Soot and ammonium record wildfires. Methane is a clue to distant rainfall. Beryllium indicates changes in solar radiation. The snow also traps air. "In between snowflakes, there are holes," says Anais Orsi, a climate researcher from the Scripps Institution of Oceanography in La Jolla, Calif. "As they get compacted into ice, it seals in the air." Each ice core is about 10% ancient airâa time capsule of the atmosphere unchanged from the year it formed. "It is as if you opened a flask of air sampled 100,000 years ago or so," says Dr. Stocker in Bern. "It gives you direct, unbiased, unchanged access to its physical and chemical properties." Spinning at 80 revolutions per minute, the $8 million drill chewed through the ice with four hardened tool-steel cutters, boring ever deeper into ice that bottoms out a mile below sea level. Every few hours, technicians from the University of Wisconsin in Madison put a narrow log of ice taken from the drill barrel into a frigid work room, where, bundled in red government-issue parkas, researchers inspected it, measured it and cut it into 3-foot sections for easier handling. Their cheeks were blushed from frost; their eyes reddened by the glare of polar ultra-violet light. Stiff wisps of hair whitened by frost framed their faces. As they handled the ice, they kept an extra pair of gloves warming in an oven, to don when their work gloves froze and fingers stiffened. They slept in unheated tents on a snowfield smooth as a starched shirt. They were allocated one bucket of snow to melt for a shower once a week and three buckets of snow for laundry. In blizzard winds, crews slung guide ropes so that people could safely feel their way to the nearest outhouse. Working conditions are so harsh the researchers consider themselves lucky to run the drill 35 days a year. By the end of January they had drilled 1.5 miles into the ice. They packaged 4,500 feet of ice cores in individual three-foot tubes, padded with snow. Then, they packed up the entire camp onto 68 wooden pallets for storage on the open ice cap until they can return next season. It may be another year or so before they can reach the bottom of the ice cap. The New York Air National Guard flew the year's shipment of ice to McMurdo Station, the main U.S. supply base in Antarctica. There it was put into three refrigerated containers for shipment aboard a freighter across the tropics to Port Hueneme, Calif., where it arrived March 8. Then, the ice was driven across the desert to Denver. The refrigerated containers each have a back-up power generator and a back-up compressor, which are triggered automatically if the temperature drops. A refrigeration technician accompanies the units. The temperature of the containers is also logged via satellite. "If it warms past minus 15 degrees C, it is worthless," says Geoffrey Hargreaves, curator of the National Ice Core Laboratory. There are four back-up systems to make sure everything stays safely frozen. In the worst case, technicians can flood the facility with liquid carbon dioxide. Sometime this summer, technicians will start sawing the ice up into small samples and shipping them to laboratories around the country, often via overnight mail. The samples then will be vaporized to free the air and elements within for analysis. At the peak of activity earlier this year, the crew guided the drill 100 feet deeper into the ice sheet every 24 hours, and another 365 years further into the past. "The drill is basically a time machine," said planetary geologist Maria Banks from the Smithsonian's Center for Earth & Planetary Studies. As she spoke, she carefully wiped down a cylinder of ice that had fallen as snow 15,800 years ago. http://online.wsj.com/article/SB10001424052748704655004575114010457906340.html?KEYWORDS=antarctic