A South Pole trek in search of global warming
Ice samples on polar trip yield clues on climate change.
(Page 2 of 2)
"It really shows the strong connection between conditions in the tropical Pacific and the South Pole," Mayewski says.Skip to next paragraph
Subscribe Today to the Monitor
Along the way, members of the three-woman, seven-man research team lived in insulated plywood bunkhouses and ate in a special mess tent on the sleds the tractors pulled. The tent doubled as the women's dorm, while one of the bunk houses did double duty as a lab. The mini tractor train also carried the fuel for transportation, heat, and electric generators.
The expedition was conducted under the aegis of the International Trans-Antarctic Scientific Expedition (ITASE), a multi-year program of Antarctic research involving 19 countries.
Where some polar field projects are interested in pinning down the physical processes determining how the climate system works at high latitudes, ITASE is trying to gather climate records from across as much of the frozen continent as possible.
"Antarctica is one of the most data-sparse areas on the planet" when it comes to climate, notes David Bromwich, an associate professor of atmospheric science at Ohio State University.
The ice-core samples provide tree-ring-like information on precipitation levels. They also trap air samples and particles from past events such as volcanic eruptions or major storms. By taking cores from regions where the layers are relatively flat, and calibrating them using the past 50 years of instrument measurements, the cores can provide a more comprehensive window on climate than information from a handful of locations on the continent.
In addition, researchers are using radar to map the bedrock far below the ice sheet's surface. The radar also is proving useful for exploring ice layers without the need to drill or dig trenches, and for spotting crevasses ahead of the tiny convoy.
The deep radar aims to see how the bedrock influences the surface shape of the ice sheet, according to expedition scientist Steve Arcone, a geophysicist with the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory in Hanover, N.H.
That information is critical to selecting sites for coring because ice layers can get compressed and jumbled as the sheet glides over bedrock features, making interpretation of the layers more difficult.
One solution was to use a shallower radar scan. That resulted in layers of ice showing up in the radar return, yielding a way to gauge year-to-year snowfall rates - a key to understanding the degree to which the ice sheet is losing or gaining mass, and an indicator of historic weather patterns.
The radar returns seem to vary in strength every six miles or so, Dr. Arcone says. "It looks like the radar picked up different climate regimes" as it moved from region to region.
Between the radar data and weather balloons the team regularly launched, the researchers took measurements "from bedrock to 23 kilometers above the ice surface," Mayewski says.