Researchers from Ohio State University are hopeful that the new core they drilled through an ice field on the Antarctic Peninsula will contain ice dating back into the last ice age. If so, that record should give new insight into past global climate changes.
The expedition in early winter to the Bruce
Plateau, an ice field straddling a
narrow ridge on the northernmost tongue of the southernmost continent, yielded
a core that was 1,462 feet long – the longest yet recovered from that region of
And while remarkably successful, the field work tested the
researchers' resilience more than most of their previous expeditions.
"It was the field season from hell," explains
Ellen Mosley-Thompson, professor of geography at Ohio State University and leader of the project.
"Everything that could go wrong did, and almost everything that could
Bad weather delayed their transport to the remote drill site,
and snowstorms were a recurrent problem, preventing support flights in to the
team. Twice, their drills became stuck deep in the ice, a drill motor broke,
and all three of the drill gearboxes failed, causing them to cannibalize those
devices to construct a new one.
Their ice core drilling effort was part of the much larger
Larsen Ice Shelf System, Antarctica (LARISSA) project, designed to unravel past
climate conditions in this part of the continent and monitor current ocean and
atmospheric processes to better understand what likely caused portions of the
massive Larsen Ice Shelf to disintegrate in 2002.
This large, interdisciplinary National Science Foundation
project involved experts in the oceanography, biology and geology of the
region, in addition to the ice core effort. The goal is to build a climate
history of the region, hopefully determining if the ice shelf break-up was part
of a long-term natural cycle or linked to the recent warming in this part of
After an earlier team of LARISSA researchers had used
ground-penetrating radar to map the bedrock under the ice field, and identified
a suitable drill site, the six-person team was flown to the Bruce Plateau from
the British research station, Rothera, on the west side of the Antarctic
Arriving at the location, the team set up sleeping tents, a
cook tent and the large geodesic dome that protected the drilling and core
processing operations. The team began drilling on New Year's Eve, Dec. 31,
Two days later, the team had drilled 459 feet when the drill
became stuck in the ice. Leaving that drill in the ice, they began drilling a
second hole, and by Jan. 21, they had retrieved 1,256 feet of core before that
drill also became stuck.
They modified a device normally used to bale water from the
drill hole to carry ethylene glycol (antifreeze) down to the top of the stuck
drill. After several days, the drill broke free, and drilling resumed.
"The guys on our team, Victor Zagorodnov and Vladimir
Mikhalenko, engineered through each problem that arose and were really very
creative," explains Mosley-Thompson, a researcher with Ohio State's
Byrd Polar Research
On Jan. 28, the team reached the bedrock at the bottom of
the ice sheet. The same day, they recovered the first drill that had become
stuck in early January. Both ice cores were cut into roughly 1-meter-long
segments that were packaged in plastic sleeves and cardboard tubes, and stored
in a snow pit adjacent to the drilling dome.
Periodically, as weather allowed, the planes would come pick
up the ice-filled tubes, packed in insulated boxes, and return them to freezers
at Rothera. Still stored at the Rothera station, the cores will be transferred
to the U.S. research ship
Nathaniel B. Palmer, shipped to the U.S. West Coast and brought to Columbus by refrigerated
truck. The cores are expected to reach Ohio State
When the ice arrives, researchers here will begin their
analyses, measuring oxygen-isotopic ratios – a proxy for temperature, and
concentrations of dust and various chemicals – including volcanic tracers – that
collectively should reveal past climate conditions.
Along with Mosley-Thompson, Zagorodnov and Mikhalenko, other
members of the team included Roberto Filippi, Thai Verzone and Felix Benjamin
Deepest Core Yet Drilled from Antarctic Peninsula
April 15, 2010