EARTHSC 1G03 Lecture Notes - Lecture 39: Permafrost, General Circulation Model
19 Apr 2017
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Document Summary
Variation in global geometry milankovich theory: eccentricity of orbit, periodically, earth orbit goes from circular to elliptical on a 100. Periodically, precession, tilt, and eccentricity reinforce each other, leading to cyclic variation in heat input from the sun. Short-term changes: once an ice age is started, periodic cycles of glacial advance and retreat take over, milankovic (orbital) cycles control the input of solar heat. Pollen identified in lake cores and glacial sediment: type of pollen can track changes in vegetation over time, 14c dating. Plot many sites on maps and you can visualize the advance and retreat of glaciers. 18o/16o ratio in glacial ice: can also be measured in marine shells / sediments, records are so tightly linked that we use orbital cycles to date marine sediment cores. In general, throughout canada: warmer, drier summers, warmer winters prediction varies from region to region.
