Researchers have recovered a nearly two-mile-long cylinder of ice from eastern Antarctica that contains a record of atmospheric concentrations of carbon dioxide (CO₂) and methane--two potent and ubiquitous greenhouse gases--spanning the last two glacial periods. Analysis of this core shows that current atmospheric concentrations of CO₂--380 parts per million (ppm)--are 27 percent higher than the highest levels found in the last 650,000 years.

The ice core data also shows that CO₂ and methane levels have been remarkably stable in Antarctica--varying between 300 ppm and 180 ppm--over that entire period and that shifts in levels of these gases took at least 800 years, compared to the roughly 100 years in which humans have increased atmospheric CO₂ levels to their present high. "We have added another piece of information showing that the timescales on which humans have changed the composition of the atmosphere are extremely short compared to the natural time cycles of the climate system," says Thomas Stocker of the University of Bern in Switzerland, who led the research.

The core is a result of the European Project for Ice Coring in Antarctica (EPICA) and it extends the climate record 210,000 years further back than what previous ice cores from Vostok Station on the same continent had documented. Scientists can determine ancient atmospheric concentrations by measuring CO₂ and methane levels in tiny air bubbles trapped in such ice, formed when the ice fell to the earth as snow. By comparing the EPICA air bubbles data to that from other ice cores and marine sediments, researchers can create a reliable picture of the climate over time.

This record also seems to show that the rise in methane levels in the last 10,000 years--thought by some to be a result of human agriculture--could simply be the result of natural variability in the decomposition of plants in boreal forests and wetlands.

The research appears in the current issue of Science and presents a larger target for climate modelers to hit in fine-tuning their computer simulations. Therefore, it may ultimately help predict what climate changes the future holds. But this cold, gray ice already makes clear that humans have steered the atmosphere into unusual territory.

5 Comments

1. 1. David Watkins 08:37 PM 6/15/08

   How ludicrous it is to consider that it is humans that are responsible for climate change through CO2 emisions, when over the past 650,000 years the CO2 in the atmosphere has varied from 180 to 380 parts per million, when the total human content is only 19 parts per million. Over the past 10 years, humans have added 1,5 parts per million yet 78.5 parts per million has come from natural sources. If CO2 can vary by as much as 200 parts per million when the human content is only 19, then human CO2 cannot possibly be respnsible for climate change. Climate change drives CO2 levels, not the other way round. If a study was conducted on solar radiation levels as the variable instead of CO2, we would have a much better and more accurate indication of climate change.

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2. 2. Bradley 02:58 AM 6/16/08

   It is ludicrous to state that it is ludicrous to think that human activities may have an effect on climate.
   
   So you propose that it is impossible that the statement below, from the article in question, points to a possibility that the increasing CO2 emissions from human activity--for a relatively short period of the 650,000 years measured--could have contributed to the current 27% higher atmospheric CO2 than seen during the rest of the 650,000 year period, despite there having been massive volcanic sources (at least one) much earlier during the period studied?
   
   http://news.nationalgeographic.com/news/2001/08/0828_wireyellowstone.html
   
   
   [i]"Analysis of this core shows that current atmospheric concentrations of CO2--380 parts per million (ppm)--are 27 percent higher than the highest levels found in the last 650,000 years."[/i]
   
   I wonder how you would propose to support your conclusion? I personally don't get the same conclusion and it is not clear to me that your math makes your conclusion more plausible.
   
   --
   Edited by Bradley at 06/15/2008 8:00 PM

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3. 3. TAParmer 01:48 AM 7/25/08

   wow, I hope the sky-is-falling type people open their eyes one day and realize they are being fed rhetoric on just about everything they digest relating to "man is contributing significantly to global warming" In Bradley's argument, C02 and methane are the causes of greenhouse gases that lead to global warming. What if anthropogenic (man-made) C02 and Methane contributed less that 4% to total greenhouse gases? (US Department of Energy, 2000)
   
   By the way, I wonder how many years are included in the "current atmospheric" period the above article vaguely pinpoints? One can see that a one year period means something entirely different than a 1,000 year period.

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4. 4. pgtruspace 03:11 AM 6/3/09

   Actually little is known about the long term behaviour of CO2 and other gasses in compressed snow/ice. CO2 is very soluable in water and ice under cold high pressure conditions. It is quite possable that not all the CO2 is still present. At the present there has been no real determanation of this.
   Also all ice cores show that CO2 contant follows temperature changes and is not a leading indicator.

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5. 5. Larry-wa 06:24 PM 10/31/12

   While CO2 is heavily involved in the present Global Warming, it cannot be construed that CO2 was the cause ending the last ice age at 11,700 yBP. A Poly-Celestial Structure ( PCS ) was the primary cause and CO2 was a byproduct of the PCS process. But, The EPICA ice core was forefront in discovering the PCSs that may have ended ice ages for millions of years. Nevertheless, Global Warming is here and it is going to be a difficult problem to deal with.
   In the text book: " The End of The Last Ice Age " there are two suggestions for controlling Earth's climate. The best one is practical with a huge investment. The second will make Central America disappear.
   Search for the text by ISBN 9780984918119.
   Thanks.

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