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What else can ice cores tell you?
Scientists can measure concentrations of two greenhouse
gases—carbon dioxide and methane—trapped within
air bubbles in the ice. This can help tell them how long the
greenhouse effect has been around and help them predict how
much may be part of natural cycles versus effects produced
induced by humans. Scientists can also measure hydrogen
peroxide in ice cores taken from locations with distinct
seasons to determine where the annual layers are. Hydrogen
peroxide is created by a chemical reaction that requires
ultraviolet light—the higher the concentration of
hydrogen peroxide, the more likely the layer was formed in
summer when there is more light. The tephra (volcanic ash) and
sulfate in the ice allow reconstruction of the earth's
volcanic history long before humans were around to observe and
document eruptions. At low latitudes these layers can also
preserve pollen, organic matter, and even insects!
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