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Video courtesy of the NSF.

Ice Cores for Studying Past Climate

Climate scientists use "proxy data" to study climates of the past, before humans with thermometers began keeping temperature records. These "proxies" include tree rings, layers within ice cores pulled from glaciers and ice sheets, growth layers in coral, and layers of sediments from the bottoms of lakes and oceans.

Gases, dust, and other materials trapped in ice can provide clues about climates of the past. Scientists dig ice cores from the Antarctic Polar Cap, the Greenland Ice Sheet, and glaciers around the world. Air bubbles in the ice trap miniscule samples of Earth's atmosphere from the past, providing scientists a way to measure levels of carbon dioxide and other gases in prehistoric times. The thickness of ice bands tells us about past snowfall rates. Darkened layers of ice contain dust, providing further clues about past climates. Some ice core data from Antarctica provides information about climate to more than 700,000 years in the past, a period which spans eight ice age cycles!

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Last modified September 9, 2010 by Randy Russell.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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