ENVR 200 Lecture 15: ENVR200 #15:16
23 Nov 2017
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Document Summary
General cooling trend over last 50 million yrs. Climate change over the last 2million years rhythms . Glaciation , cold and dry cannot form the ice and snow (low moisture) O18, 2more neutron then o16, o16 more easier to attach the water molecule, rain(more o16 ), When forming the ice, increasing the o16 in ice, much o18 in water, you can test the cold or warm by the oxygen. Back to equilibrium when ice start to melt. (interglacial) Long process from snow to form the ice, not usually to rain the ice. Problem: changes in insolation(paticular;y orbital eccentricity factor)are too small to account for the observed(recorded) changes in temperature. Therefore: milankovitch cycles may initiate the start and termination of glaciations but feedbacks are needed to continue glaciation process. Role of the biological pump(280ppm, 750ppm=no biologic pump) Trends driven by the plate tectonics and chemical weathering of rocks. Rhythms driven by astronomical process that affect incident solar radiation at high latitudes.
