How is CO2 measured in the geologic past?
One way that the CO2 is measured is through ice core drilling. About 5 years ago I spent 8 weeks in the bush of Alaska working with the Athabascan. During the time there I had the opportunity to visit Barrow, Alaska. There is a science station there where scientist are studying ice core drillings to measure the levels of CO2 entraped in the ice over the years. When they pull out a core of ice from a glacier the core has rings in it just like a tree trunk. These rings indicate CO2 that has gotten traped in the ice. Because glaciers are formed over and over by thawing, snow, and re-freezing, the scientist can drill deep into the core of the glacier and bring out centuries of ice and measure the CO2.
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