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FEATURE STORY 59
lakes under neath the ice. But the new technology, honed at
the University of Kansas and deployed by researchers from
both Kansas and the University of Copenhagen, can detect
even a few millimeters of water, which are just as dangerous.
What's more, whereas previous radar equipment took mea-
surements only of the ice directly beneath it, the new tech-
nology also provides information about ice layers and the ice
sheet's base in a three-kilometer-wide swath of ice cap.
During the winter of 2005--2006---summer in Antarctica---
scientists from Kansas lugged the new system down to the
West Antarctic Ice Sheet and collected data on a 30-by-10-
kilometer grid. Early results show much more detail about
which parts of the ice sheet's base are sitting on water and
which are still frozen to the ground. Whether the water
came from geothermal heat, friction from ice in motion,
or accumulation of surface meltwater is not yet clear. But
the new data should help improve ice-sheet models, says
Claude Laird, a research scientist at the University of Kansas
and a member of both the Antarctic and the north Green-
land expeditions. This summer, Laird and the other scien-
tists used the technology to map a 370-kilometer swath of
Greenland. When the results start coming in, they should
give a clear picture of that swath, and of how much water
lies within the ice or beneath the sheet.
Meanwhile, the scientists are seeking clues from the past.
At the north Greenland base station, amid the huts and vehi-
cles, an aluminum pole is staked to the ice cap. Next sum-
mer, the scientists will return to the spot and start drilling
out an ice core, boring about 2,500 meters to bedrock. They
are particularly interested in one key geologic period, called
the Eemian interglacial. During this stretch of time, from
around 130,000 to 115,000 years ago, the planet warmed.
Greenland hit temperatures 7 to 8 ºC warmer than today's,
and sea levels surged at least three to ve meters higher
than they are now. If this happened today, much of south
Florida, Bangladesh, and many other low-lying coastal areas
and islands would be submerged.
The warming during the Eemian period was caused by
eccentricities in Earth's orbit that periodically allow more
solar energy to hit the planet. An understanding of how
the climate and ice sheets responded during the Eemian
war m-up should sharpen our picture of how they'll respond
today. Already, a record of Eemian sea levels is available
from existing geological sites. But scientists would like to
know more about short-ter m climatic variations---coolings
and warmings---within the Eemian period. That should
help them better understand current climate changes and
more accurately predict how sea levels will rise.
Glaciers accrete over time, and di erent layers contain
records of Earth's past climate. A sample of ice spanning the
whole Eemian period---never before found in the northern
hemisphere---would provide a wealth of information. Identi-
fying oxygen isotopes within water molecules can reveal what
temperatures prevailed when snow fell. Trapped air bubbles
inside ice contain samples of the old atmosphere. The thick-
ness of ice layers can reveal how much snow fell. And bits
of dust and organic matter will allow accurate dating. After
conducting radar analysis, the researchers at north Green-
land think the spot marked by the aluminum pole---dubbed
NEEM, for "North Greenland Eemian"---will contain a 120-
meter-thick chunk of ice representing the entire period (see
"Quest for Ancient Ice," opposite). "We can get even better data
on these fast climate oscillations," says Laird. "And we can get
some forecasting about what climate change will mean."
In north Greenland, the science is done for the season. It
had taken the team of scientists nine days to reach the site---
a 370-kilometer slog, dragging thousands of kilograms of
equipment, fuel, and food and using two snowcats, three
snowmobiles, and a Toyota Land Cr uiser out tted with
tracks. Their trip was plagued by delays: at one point, a bliz-
zard had them hunkering down for days; at another, two of
the Land Cruiser's tracks broke. After more than four weeks
in the eld, the scientists waited to be evacuated. Though
it was only August, dangerous weather loomed, and they
were anxious to get home and analyze data they'd gathered
during their weeks of work.
But rst they had to get o the ice sheet. On a sunny after-
noon---with temperatures reaching --4 ºC---a ski-equipped
cargo plane made a soft touchdown. After disembarking,
the pilot, in his olive-green jumpsuit and wraparound sun-
glasses, kicked worriedly at a new layer of snow.
Three hours later, the nine scientists and crew members
had boarded the cargo plane. The plane labored up and
down the snowy runway. But just as the pilot had feared,
the snow was too soft for the plane to reach takeo speed.
Departure would need to wait 12 hours, until 4:00 . ., the
coldest time of day. At the appointed hour, they tried again.
This time, ice was frozen to the bottom of the plane's front
ski. The pilot's e orts to shake it loose, using hydraulics
to move the ski up and down against the snow, broke a pin
that held the hydraulics in place. Another plane needed to
deliver the replacement parts.
Finally, around 11:00 . . that night, a second cargo
plane landed. It was nearly 20 ºC below zero. A crew from
the second plane sprinted across the ice, xed the ski, and
took o again with a rocket-assisted ourish. And nally,
the original plane followed suit, skating quickly across the
icy surface. Amid the roar of side-mounted rocket motors,
the researchers and the crew made it aloft at 2:30 . ., a
day and a half after their rst try. Fortunately, the ice sheet
was frozen solid. For now.
David Talbot is Technology Review s chief correspondent.
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