COLUMBUS, Ohio -- An expedition to a glacier atop the world’s 14th highest peak in the Himalayan Mountains has returned with ice cores containing climate records that could reach back into the last glacial stage -- some 12,000 years ago.
The international expedition, led by Ohio State University researchers, included American, Chinese, Peruvian, Russian and Nepalese members and capped perhaps their most successful season in two decades of retrieving frozen climate records. The expedition was supported by the National Science Foundation.
The 40-member team reached the Dasuopu Glacier, a two-kilometer-wide ice field that straddles a flat area on the flank of Xixabangma, an 8,014-meter (26,293 feet) peak on the Tibetan Plateau. They began drilling in early September and members of the expedition worked for more than four weeks at the glacier site. No previous expeditions have ever drilled ice cores at such a high altitude.
The researchers retrieved the first core from their high camp site at 7,020 meters (23,031 feet) using electro-mechanical and thermal drills. The first core measured 159.6 meters (524 feet).
The drill site was then moved to the of the glacier summit at 7,200 meters (23,622 feet) and the researchers drilled a second core, this one measuring 149.2 meters (489 feet). A third core, this one 167.6 meters (550 feet) long, was retrieved after the drill had been moved a second time.
Both the second and third cores were drilled to bedrock and therefore, contain ice dating back to when the glacier first formed.
“These are excellent records since the temperature at bedrock was -13.8 degrees C, making this the coldest, non-polar glacier we’ve cored,” explained Lonnie Thompson, professor of geological sciences and a researcher with the Byrd Polar Research Center at Ohio State and expedition leader.
Thompson said that the cold temperatures at bedrock usually signal that the deepest ice is well preserved and the climate records it contains are therefore longer.
“Both of the cores that reached to bedrock should contain glacial stage ice dating back at least 12,000 years,” Thompson said. “But exactly how old the ice is will have to wait until we can do the laboratory analyses,” which he said could take a year or more.
The Dasuopu glacier cores should be very important for providing a more accurate picture of the monsoonal climate system that affects that part of Asia. “We think we may find some evidence for a historic link between the monsoons and the El Nino-Southern Oscillation climate effect,” Thompson said.
The monsoons in Asia directly affect one of the most populated regions on earth and make up a sizable portion of the planet’s collective climate system. Thompson’s team has drilled at two earlier sites on the Tibetan Plateau -- the Dunde ice cap in the northeast and the Guliya ice cap in the northwest.
Expedition researchers hoped that the new cores would provide a look
at annual climate variations for as much as the last 3,000 years, and 10-year
“snapshots” for climate throughout the rest of the core.
All three cores were cut into short sections, packaged and sealed in insulated
containers. They were then man-hauled down the mountain and then carried
by yaks until the expedition could rendezvous with trucks which would carry
the cargo out of the field.
The first core drilled was split and divided between the American and Chinese research teams. Core two was shipped to the Lanzhou Institute of Glaciology and Geocryology (LIGG) in China while core three was sent to the Byrd Center in Ohio, where it arrived in late October. The bottom three meters (10 feet) of cores two and three were divided for study by the Americans and the Chinese.
During the past year, Thompson’s team has retrieved new cores from ice fields on Graham Bell Island in Franz Jowef Land in the high Russian Arctic, and from Sajama, at 6,586 meters (20,608 feet), the highest mountain in Bolivia.
Participants in the expedition included Mary Davis, research associate; Bruce Koci, drilling engineer; graduate students Keith Henderson and Shawn Wight; and glaciologist Vladamir Mikhalenko.
The expedition also included four professional mountaineers from Peru -- Benjamin Vicencio, Maximo Hipolito, Alberto Magno and Jorge Albimo -- and four Nepalese sherpas -- Sherpa Lopsang, Punsham Prasal, Sherpa Mingma Geli and Sherpa Pasang Nuri. Professor Yao Tandong, vice president of the Lanzhou Institute, led 26 additional Chinese members of the expedition.