EESC1168 Lecture Notes - Lecture 4: Ice Core, Core Data, Solar Constant
1 Feb 2017
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Document Summary
Similar to tree rings, counting the years - lighter snow layers = summer snow. 2 major ways that scientists use ice core data to reconstruct past climactic trends ( paleoclimate ) Measurement of the composition of trapped gas bubbles. Measuring greenhouse gas concentrations in air bubbles. As snow accumulates, air is trapped in spaces between the flakes. The ice core is melted or crushed in a vacuum, and then the released gases are analyzed using mass spectrometry. This identifies the type and amount of gases present, so we know past atmospheric composition. An isotope is an atom with a different number of neutrons. Light and heavy isotopes occur naturally for many elements (extra neutrons for heavy) Antarctic snow has about 5% less heavy oxygen than subtropical ocean water. This difference changes depending on how hot or cold the climate is. More heavy oxygen evaporates, less heavy oxygen precipitates, more heavy oxygen makes it to antarctica.
