GEG 1301 Lecture Notes - Lecture 10: Milankovitch Cycles, Volcanism, Little Ice Age
30 Mar 2016
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GEG 1301 Full Course Notes
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As we have not been measuring and recording climatic data for very long, we must use indirect methods (proxies) Tree rings, ice/lake cores, glaciers, ocean sediments. Only useful for longer time scales, can"t determine daily/monthly changes. Ice cores, sediment varves, tree rings and coral bands all show annual data. Trapped air bubbles within the ice show the conditions of the time the air was sealed within the ice (isotopic analysis) The best place to core is where the ice moves the slowest (center) Oldest/deepest ice cores come from the antarctic. Lake core analysis examine the pollen and organics to determine the conditions. Tree rings primarily show the conditions (temp & precip) during the growing season. Can record millions of years of sediment. Takes a long time to analyse the cores. Temperatures have been much warmer & much cooler than the present. Thermal max occurred during the cretaceous: 6-10 c warmer then today. Especially in the polar regions (tropical forests present)
