Posted on 03/15/2002 8:06:39 AM PST by cogitator
Antarctic Ice Core over 500,000 Years Old Extracted
CAMBRIDGE, UK, March 14, 2002 (ENS) - Ice more than half a million years old has been taken from deep below the East Antarctic ice sheet, setting what is believed to be a new record.
The multi-nation European Project for Ice Coring in Antarctica (EPICA) drilling at Dome Concordia has recovered ice believed to be around 530,000 years old, according to the British Antarctic Survey.
Previously the Russian Vostok ice core, dating back 420,000 years, was regarded as the oldest ice to be drilled from Antarctica.
The EPICA team, from 10 countries, recovered their ice from a drill hole that reached 2,864 metres (9,396 feet) in depth - compared to the Vostok hole's 3,538 metres (11,607 feet).
According to British Antarctic Survey scientist Rob Mulvaney, the answer to this paradox lies in differences in the rates of thinning of the ice sheet at the two sites, which is linked to what lies beneath them.
At Dome Concordia, high on East Antarctica's plateau, the ice lies on rock, whereas at Vostok, it stands over the huge Lake Vostok.
"If the bottom of the ice sheet lies on rock, and there is no melting, then the ice at the very bottom is almost infinitely old, and the annual layers infinitely thin," Mulvaney said.
"Because Vostok ice is melting at the base, the oldest layers have been lost, and the vertical column of ice does not need to thin so rapidly to maintain the surface equilibrium."
The EPICA project exceeded its targets in the past season, drilling more than 350 metres (1148 feet) beyond its goal, and leaving just 380 metres (1246 feet) to be drilled next season.
The British Antarctic Survey (BAS) said field analysis already suggests that the ice retrieved coveres four glacial and interglacial periods, with every prospect of several more climate cycles before the team reached either disturbed ice or bedrock.
EPICA's chief scientist, BAS's Eric Wolff, said the drilling program took scientists back to the future. "Information about how climate worked in the past is locked in the ice," he said. "Understanding this helps predict future changes."
The EPICA project has also begun drilling 3,000 kilometers (1,864 miles) from Dome Concordia in Dronning Maud Land in search of more detailed information at a site that receives double the snowfall of Dome Concordia.
Even so, it is cores at Dome Concordia that will provide the longest possible record of the past atmosphere, BAS said.
The single most important source of information about past climate change and the associated composition of the atmosphere are the two large ice caps of Greenland and Antarctica, EPICA says in its mission statement.
"Analysis of ice cores is therefore the most powerful means we have to determine how climate has changed over the last few climate cycles, and to relate this to changes in atmospheric composition, in particular to concentrations of the principal greenhouse gases - CO2, CH4 and N2O - carbon dioxide, methane, and nitrous oxide."
EPICA says the program "has been motivated primarily by the urgent need to predict more accurately how global climate is likely to respond to increased emissions of greenhouse gases as a result of human activities."
Excuse me if I get this wrong, but isn't this "understanding" subjective to the interpretation of said data.
It would be interesting to know how much this project cost the taxpayers.
And I thought my freezer needed defrosting?!
It's ammusing that they tack on the extra significant figure when they are pretty much taking a wild guess. Must be some conversion from metric or something.
That reminds me of the time I was working at the refinery dumping bags of chemicals into a big mixing tank.
The bags were labeled:
40 lbs.
18.1437 kg.
Awesome. Also they are not down to bedrock, so there is more to the record if they can reach it.
This project didn't cost the U.S. taxpayers anything (it's a British Antarctic Survey project).
Yes, but as I noted in the comment, the deeper they go the more the record gets smeared. The last few meters of the GISP core (Greenland) weren't really useful. I think it's because the ice is moving, and near the bedrock it's somewhat anchored, so the ice layers get "stretched".
Still, it's quite an accomplishment, and this is a great dataset for comparison. It might help figure out why some Antarctic areas are cooling and some areas are warming. (Then again, it might not.)
LOL - What a bunch of idiots they were, huh?
Everybody knows that 40# = 18.143696 kg! 8^)
That's what they try to do. It helps to have a definitive date to help fix some of the layers in time. Volcanic eruptions deposit ash and high sulfur content in the ice. Counting layers and finding signals from the Krakatoa/Krafla/Tambora/Thera (Santorini) eruptions helps indicate if the layers in the ice are truly annual or not.
Palaeo Environment (Ice Cores)
Paleo Slide Set: Low Latitude Ice Cores: High Resolution Records of Climatic Change and Variability in the Tropics and Subtropics (has a picture of ice core layers)
That's actually quite easy. Glacial ice has bubbles of air under pressure in it. If you put it in a glass of water, as it melts it pops and fizzes, and is supposedly very entertaining. (I've only heard this, haven't actually seen it demonstrated.)
It's nice to see such precise use of words like "infinite" from scientists.
Being in Alaska,I have the opportunity to observe ice and snow on a seasonal basis. One thing I have noticed is that sediments get moved out after a while; they migrate out of the ice leaving pure ice behind as the snow recrystallizes over and over. Of course their core sample is fairly long, almost 2 miles, so it probably does show layering with fair definition. But at depth there would be time for the ice to purify itself. If they can count half a million layers, that in itself is remarkable.
In other words, they are not there to learn, they are there to prove, and that affects their interpretations and conclusions.
I think that's a jaded comment, sorry. Most of the work done on the cores will be basic research: measuring the oxygen isotopes, conductivity, sulfur content etc. in each layer, and then analyzing that data. Correlating it with known causes, known cycles and seeing what doesn't fit. Then the job of science is to try and figure out what doesn't fit and finding a way to make it fit.
I think the guys doing the drilling and analyzing the core won't be in the business of interpreting. That'll be left to the folks back home in their warm comfy offices.
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