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(i)

Understanding Our Planet Through Chemistry

IIc. Environment

Global change in the geologic past

An exciting new application of the QMS instrument uses a high-energy laser fired through a modified microscope to open individual gas inclusions in ice. Ice from Greenland and Antarctica contain atmospheric gases that were captured in snow as it formed. The gases were retained as the snow turned into ice and formed bubbles. Analysis of these bubbles provides detailed information on the past composition of the atmosphere.

Photo of scientist sampling snowpack trapped air at Greenland Ice Sheet. Scientists sample air trapped in the snowpack at the Greenland Ice Sheet Project 2 site in Central Greenland. These samples will be analyzed by mass spectrometry to determine the composition of ancient air. These studies help us to predict climate changes. [144k]

Sea-level changes, changes in solar activity, and, according to some astrophysicists, even the signals from distant supernovas, are also recorded in the ice. Compiling and studying this record helps us to evaluate current changes in the atmosphere and to predict future trends. Ice-core studies provide valuable information about the levels of human pollution, past climate patterns, sources of moisture, the altitude of the ice when it formed, frequency and magnitude of natural events, and biological activity at the ocean surface.

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