Lab
supplies Arctic, Antarctic ice cores critical to climate research
It's a freezing cold day inside the
National Ice Core Laboratory (NICL) in Denver, Colo., as it is every day of the
year. That's because the NICL is a facility for storing and studying ice cores
recovered from the polar regions of the world. It's minus 23.3 degrees Celsius
(minus 10 degrees Fahrenheit) inside, so everyone is bundled up in ski parkas,
insulated gloves and boots. And, saws are buzzing, as scientists from all over
the U.S. are measuring and cutting pieces of precious Antarctic glacier ice to
take back to their labs for research.
"I'm here to cut gas samples out of this
core," says Murat Aydin, a chemist who's visiting from the University of
California, Irvine.
"I'm looking at the mineralogy of
the ice," says Donald Voigt, a geoscientist from Penn State.
"I'm studying the stable water
isotopes that tell us about past temperature changes," adds Brad Markle, a
geochemist from the University of Washington.
While their research goals vary, all the
scientists are here on this day for same thing--ice cores from the WAIS Divide
Ice Core project. WAIS stands for West Antarctic Ice Sheet. The WAIS Divide is
a high point on the ice sheet where the ice begins to flow in different
directions.
"We started this ice core project
in 2005," says manager Mark Twickler. With support from the National
Science Foundation (NSF), Twickler and a team of scientists, engineers and
support personnel traveled to the bottom of the world to drill and bring back
these ice cores, which are perfectly preserved records of the distant past.
The ice cores were taken from a giant
ancient Antarctic ice sheet more than 70,000 years old. An ice sheet is a
permanent layer of ice covering an extensive tract of land. The team drilled
down more than two miles to retrieve the oldest pieces of ice in the sheet. The
cores were carefully packed and shipped back to the U.S. and stored in a giant
freezer at the NICL. The temperature in the freezer is minus 40 degrees Celsius
(and Fahrenheit), and it contains more than 18,000 meters, or ten miles, worth
of ice cores.
Twickler says ice core layers are like
tree rings because each layer represents a year of weather. "The unique
thing about polar glaciers is that each year brings another layer of snow. So,
you get one year's worth of snow on top of the previous year. The layers
compress, so everything that fell out of the atmosphere, including dust, salt
from the ocean and volcanic ash, is preserved in the ice core," explains
Twickler.
"There are times where it snows less for
a couple years, and then it snows more for a few years, and by looking at the
composition of the snow, we can tell what the temperatures were, how rough the
oceans were around Antarctica, and even how dusty it was in Australia. We can
tell whether the dust came from Australia or South America, so in that way, we
know the winds were stronger and drier in one region, or the other. We can also
look at the electrical properties of the ice from year to year. So, it's
basically like looking at a weather report, year to year, going back in time,"
continues Twickler.
"The National Ice Core Lab is a
world class facility that has been in operation for close to 20 years now, as
well as a unique training ground for students, some of whom began as
undergraduates and have now gone on to graduate school because of their
experience at the lab," says Julie Palais, program manager for the
Antarctic glaciology program within the NSF's Office of Polar Programs.
"In addition, the facility houses one of the most unique collections of
scientific samples in the world, and group tours provide a wonderful
opportunity for members of the public and school children to learn about the
important work being done on samples from both polar regions." Arctic as
well as Antarctic samples are stored at the facility.
Some scientists study the bubbles
trapped within the cores--each a tiny pocket of air, frozen in time. "We
can take those bubbles and measure a variety of gases that were in the
atmosphere at the time the bubbles were formed," says Twickler.
The National Ice Core Laboratory is
operated and maintained through an interagency agreement between NSF and the
U.S. Geological Survey (USGS).
"The NICL facility provides the ice
core research community with the capability to conduct examinations and
measurements on ice cores, while preserving the integrity of these cores in a
safeguarded, temperature-controlled environment. This is accomplished with
multiple backups built into the refrigeration system and a 24/7 alarm system to
alert us of any problems that occur," explains Betty Adrian, NICL acting
technical director.
USGS scientist Joan Fitzpatrick is
looking at WAIS Divide ice core samples to research how ice sheets respond to
changing climate. In order to do that, she creates thin wafers of ice from the
core and then places the wafer samples under a microscope to analyze individual
ice crystals.
"If the climate is warming, is the
ice sheet going to get thinner overall? Is the ice sheet going to fall apart
around the edges or is it suddenly going to slide off the continent?" asks
Fitzpatrick. "We really don't have a good handle on how the ice sheet as a
whole will respond in a changing climate. The water that comes out of the
melting ice sheets melts into the oceans and can raise sea level. This is a key
issue for the public," she adds.
"These icy blasts from the past are
helping researchers better understand the mechanics of climate change,"
says Linda Morris, education program manager for the U.S. Ice Drilling Program.
"Ice cores give us this long historical record of what naturally has been
occurring to the Earth's climate for hundreds of thousands of years. More
recent patterns emerging from times when humans have inhabited the Earth can
then be evaluated against this long term data to more meaningfully assess the
impact of our behaviors on climate. It's an exciting inquiry and an important
one if we are to be good stewards of our environment into the future."
Miles O'Brien, Science Nation
Correspondent
Ann Kellan, Science Nation Producer
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