WELLINGTON, New Zealand (AP) — Nancy Bertler and her team took a freezer to the coldest place on Earth, endured weeks of primitive living and risked spending the winter in Antarctic darkness, to go get ice — ice that records our climate's past and could point to its future.
They drilled out hundreds of ice cores, each slightly longer and
wider than a baseball bat, from the half-mile-thick ice covering
Antarctica's Roosevelt Island. The cores, which may total 150,000 years
of snowfall, almost didn't survive the boat ride to New Zealand because
of a power outage.
Bertler hopes the material will help her estimate how long the Ross Ice Shelf would last under the current rate of climate change before falling apart.
Evidence from the last core her team hauled out needs further study,
but it contains material that Bertler said appeared to be marine
sediment that formed recently — at least in geological terms measured in
thousands of years.
That would bolster scientists' suspicions that the shelf could
collapse again if global temperatures keep rising, triggering a chain of
events that could raise sea levels around the world.
"From a scientific point of view,
that's really exciting. From a personal point of view, that's really
scary," said Bertler, a senior research fellow at the Antarctic Research Centre at the Victoria University of Wellington.
The ice shelf acts as a natural barrier protecting massive amounts of ice in West Antarctica,
and that ice also could fall into the ocean if the shelf fell apart.
Scientists say West Antarctica holds enough ice to raise sea levels by
between 2 meters (6.5 feet) and 6 meters (20 feet) if significant parts
of it were to collapse.
Ted Scambos, the lead scientist at the National Snow and Ice Data
Center at the University of Colorado, said that even under the worst
case scenario he thinks it would take at least 500 years for West
Antarctica's ice to melt.
However, he said a discovery of sediment would indicate a significant
portion of the ice shelf is under threat of becoming unstable again,
and that the implications were "huge."
Bertler hopes the material she recovered will help her to estimate by
the end of this year whether it will take 50 years or 500 years for the
ice shelf to collapse at the current rate of climate change. Those
answers should prove important for policymakers who, she said, may need
to decide whether to build sea walls or move populations to higher
ground.
Bertler's project is one of scores that take place on Antarctica
every Southern Hemisphere summer. To scientists, the continent's
pristine habitat offers a unique record of the planet's weather and a
laboratory for studying the effects of climate change.
Studies indicate that while the Arctic has suffered what scientists
consider to be alarming rates of ice loss in recent years, the Antarctic
ice shelf has remained relatively stable despite having have lost ice
in recent decades.
Research in Antarctica creates huge logistical and personal challenges.
Bertler's camp on Roosevelt Island is a three-hour flight from the
nearest permanent Antarctic outposts, Scott Base and McMurdo Station.
The island is surrounded by the Ross Ice Shelf, the world's largest mass
of floating ice, covering an area the size of Spain.
Even during the spring and summer months when Bertler's team was
working there, the temperature sometimes dropped to minus 25 C (minus 13
F) and there were frequent storms and thick fog.
At one point bad weather even compelled logistics experts to prepare a
plan to keep the 14-member team there through the Antarctic winter,
four months of almost total darkness and temperatures that can drop to
minus 60 C (minus 76 F).
The weather improved, but the round-the-clock daylight of the
Antarctic summer is grueling enough. Bertler, 42, who has spent nearly
every summer there for 14 years, says its boundless frontiers can feel
like a prison, though she has grown to love the exceptional landscape.
While on the island, the team's only form of communication was three
satellite phones. Every person carried a GPS unit in case he or she got
lost in the fog or storms.
The crew worked 10-hour shifts, read, occasionally skied
cross-country. Some found it difficult to sleep in permanent daylight.
"Everything becomes quite primal, in a way," Bertler said. "You're just
thinking about your daily survival, being safe, and doing the work that
you're there to do."
The team used a sophisticated drill to collect cylinders or cores of
ice. To ensure the samples stayed cold enough to get safely to New
Zealand, the team had to do something that seemed counterintuitive:
import a freezer to Antarctica.
Still, the thousands of years of history collected in the ice cores
almost melted away on the voyage home, when huge waves knocked out power
to the freezer and swamped a backup generator. It was 36 hours before a
technician could get on deck and restore power. But the ice stayed cold
enough and reached the project's base in Wellington, the New Zealand
capital, last month.
The cores consist of sandwich-like layers of ice, formed when annual
snowfall compacts to a fraction of its original depth. Bertler said she
believes most of the ice she has collected is less than 40,000 years
old, although the final pieces near the rock bottom could be up to
150,000 years old.
The material Bertler thinks may be marine sediment came from 760 meters (2,500 feet) deep.
Richard Levy, a New Zealand scientist who specializes in past
climates and who was not involved in Bertler's research, said the
project provides a high level of detail about climate change over
relatively short periods of time.
The layers of ice allow scientists to measure atmospheric gas levels
on an almost annual basis going back thousands of years, he said. That
complements rock-drilling work Levy and others have done in the
Antarctic interior, which tracks climate change over longer time
horizons of several million years, he said.
Bertler's project has taken about seven years to complete and cost
about 11 million New Zealand dollars ($9.2 million), most of which has
come from the New Zealand government. Scientists from Australia,
Britain, China, Denmark, Germany, Italy, Sweden and the U.S. also are
involved.
Tim Naish, a colleague of Bertler's who heads New Zealand's Antarctic
Research Centre, said that if Bertler has indeed found recent marine
sediment, it could be significant.
"It will provide insight into what happens when the Earth warms," he said.
__
McGuirk reported from Scott Base, Antarctica.
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Because of weather events like Hurricane Sandy that wouldn't have been such an event if the oceans hadn't been rising so fast, knowing when and how fast the ocean will continue to rise is important especially during storms when ocean levels can rise and from wind blown waves as they approach shores throughout the world.
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