Frozen crystal balls: ice cores offer clues to the climate.
At a site called Dome C Dome C, also known as Dome Circe or Dome Charlie, located at Antarctica at an altitude of 3,233 m or 10,607 ft above sea level, is one of several summits or "domes" of the Antarctic Ice Sheet. on the eastern side of the Antarctic continent, the European Project for Ice Coring in the Antarctic (EPICA) recently removed cylinders of ice from a depth of nearly two miles. When the crew returns in December to finish the five-year project and remove the last 328 feet of ice, they will uncover a bedrock layer that has not been touched by light or air in more than 900,000 years.
But why is old ice so interesting to the scientific community? "What you see in this record, combined with earlier data, are the rules by which climate works, and these are the rules that go into climate models for prediction of the future," says Eric Wolff, chief scientist of the EPICA program, and member of the British Antarctic Survey Based in Cambridge, the British Antarctic Survey (BAS) is the United Kingdom's national Antarctic operator and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council and has over 450 staff. .
Ice coring began in the 1950s, and since then researchers have been removing samples from the Arctic, Antarctic, and any other location where ice accumulates unhindered unhindered
not prevented or obstructed: unhindered access
without being prevented or obstructed: he was able to go about his work unhindered by melting. A trove of information about the atmosphere and environment waits inside, gleaned from the physical properties of the ice itself, and from the antique air bubbles within it. "It is a direct link to the atmosphere," says Mark Twickler, director of the National Ice Core Laboratory The National Ice Core Laboratory (NICL) located at the Denver Federal Center is the primary repository for ice cores collected by the United States. The facility is managed by the United States Geological Survey (USGS), and jointly funded by the USGS, National Science Foundation, . "With all other ways of getting data, you have a water surface in the way. Even tree rings have some mediation."
Researchers have discovered several things about the planet through ice coring. We know that for the last 800,000 years or so, the Earth's climate has shifted back and forth between ice age conditions and warm, inter-glacial periods, such as the one we're in right now. Dust in the ice hints at events that influenced climate, such as volcanic eruption eruption /erup·tion/ (e-rup´shun)
1. the act of breaking out, appearing, or becoming visible, as eruption of the teeth.
2. and the circulatory circulatory /cir·cu·la·to·ry/ (ser´ku-lah-tor?e)
1. pertaining to circulation, particularly that of the blood.
2. containing blood.
1. power of the Earth's winds.
Researchers are also able to watch the ebb and flow the alternate ebb and flood of the tide; often used figuratively.
See also: Ebb of elements through the environment. Lead levels in the ice increased measurably in the layers corresponding to the introduction of leaded gasoline, and decreased just as sharply in layers corresponding to its removal from the market.
Ice coring allows scientists to gain perspective on our atmosphere and greenhouse gases greenhouse gas
Any of the atmospheric gases that contribute to the greenhouse effect.
greenhouse gas . "Maybe the most important thing we can see in respect to human activity, [is that] we can show the atmospheric composition we have now is really unlike anything we've had for the last 100,000 years," says Kurt Cuffey, an earth sciences professor at the University of California, Berkeley The University of California, Berkeley is a public research university located in Berkeley, California, United States. Commonly referred to as UC Berkeley, Berkeley and Cal . "Fossil-fuel burning and agricultural practices have all had an effect. Right now, atmospheric levels of [the global warming global warming, the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. gas] carbon dioxide carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. (CO2) are about 30 percent higher than their preindustrial pre·in·dus·tri·al
Of, relating to, or being a society or an economic system that is not or has not yet become industrialized.
of a time before the mechanization of industry levels."
Climate models are now being constructed to look 100, 200 and even 300 years into the future. These complex computer models take in such variables as predicted international economic growth, population size and projected dependence on fossil fuels fossil fuel: see energy, sources of; fuel.
Any of a class of materials of biologic origin occurring within the Earth's crust that can be used as a source of energy. Fossil fuels include coal, petroleum, and natural gas. . The models must also realistically render the myriad systems that the Earth employs to regulate itself. Data from ice cores is used both to create these representations, and to check the accuracy of the model.
Modelers can run the simulation backward in time to see if it predicts the actual data. "The models do a pretty good job explaining why world temperatures for the last 10,000 years have been 10 to 15 degrees higher than in the ice age," says Cuffey. "It seems to answer the critical question that if you change carbon dioxide by such and such an amount how much will you change the temperature."
The major problems with the models lie in how accurately they depict de·pict
tr.v. de·pict·ed, de·pict·ing, de·picts
1. To represent in a picture or sculpture.
2. To represent in words; describe. See Synonyms at represent. the feedback systems of the Earth. Models failed to predict a series of sudden climate change events that happened during the period of the ice ages, but there is hope for their improvement.
"Given more information about the past, we hope we can make better predictions about the future," says Twickler. Before the EPICA project, climate records only dated back 400,000 years or so. EPICA more than doubled the scope of climate data.
Wolff says that at a recent conference of field experts "there was general support to look for somewhere in Antarctica to find even older ice, more than one million years old. This will require a lot of survey and modeling work, and we agreed that it should be a truly international effort."
Another expedition may also be underway next year. Kendrick Taylor, research professor at the Desert Research Institute in Nevada and leader of a possible U.S.-fronted trip to the Antarctic, says there are plans to drill a core reaching back only the last 100,000 years. "EPICA focused on long time scales. It's really a great tool," says Taylor. "We're taking a slightly different tactic, and looking at only the last 100,000 years. There's better time resolution."
As researchers probe deeper and deeper down in the ice sheet, the layers of ice tend to become thinner, sometimes only fractions of an inch thick. These layers inevitably lack the year-to-year information of more recent, thicker layers, and span larger periods of time. This is why the EPICA core falls short. "We want to see what the last warm period was like, and how it shifted from warm to cold," Twickler says. "This should help us understand the time scale of change, and see what is happening. We need to see conditions of the past atmosphere to see how activity has altered it." CONTACT: EPICA, (011)+33(0)3-88-76-71-06, www.esf.org; National Ice Core Laboratory, (303)202-4830, http://nicl.usgs.gov/index.html