Do you see the bubbles in this piece of Antarctic ice? The bubbles contain carbon dioxide and other gases that were trapped in the ice when formed thousands of years ago. Researchers carefully crush the piece and capture the gases that escape when the bubbles break. This allows them to better understand what carbon dioxide levels were over time.
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Courtesy of Oregon State University

Gas From the Past Gives Scientists New Insights into Climate and the Oceans
News story originally written on October 3, 2008

To learn what Earth’s atmosphere used to be like, scientists have been studying ancient air.

The ancient air is within tiny bubbles in 390 samples of ice from Antarctica. The bubbles tell what Earth's atmosphere was like 20,000 to 90,000 years ago.

Today, as the amount of greenhouse gases in Earth’s atmosphere continues to grow and the greenhouse effect gets stronger, scientists are concerned that this may cause a change in the circulation of the ocean. Comparing the data from the air bubbles with other data about what the planet was like at that time, scientists are able to learn whether this has happened in the past.

Interested in learning more about the connection greenhouse gases, climate, and ocean circulation, scientists Jinho Ahn and Edward Brook analyzed the bubbles. Sections of the samples were carefully crushed, releasing gases from the little bubbles. The level of carbon dioxide in each ancient gas sample was measured.

The scientists compared the amounts of carbon dioxide found in the ancient air with climate information about the temperature of our planet at the time when the gases were trapped in the ice. They also compared the carbon dioxide levels from the ancient air with ocean sediments in Chile and the Iberian Peninsula. The sediments preserve evidence of how fast or slow the ocean currents were.

What did they find? The data suggests that carbon dioxide levels, global warming, and ocean currents are tightly related. They found that samples of ancient air that contained more carbon dioxide were from times when Earth’s temperature was higher. They also found that these were times when ocean currents were weaker.

And if it has happened in the past, it may happen in the future, say the scientists. And changes in ocean currents could cause even more carbon dioxide to get into the atmosphere.

Last modified January 11, 2009 by Lisa Gardiner.

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