GEOG 210 Lecture Notes - Lecture 6: Photosynthesis, Extinction, Externality
18 Nov 2020
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Document Summary
95% of scientists agree that climate change is anthropogenic. But, nevertheless, at the center of this question is the carbon cycle. The carbon cycle the movement of carbon between the crust, oceans, atmosphere, plants, soil, and animals. About 90% of the earth"s carbon is held in the crust, and geologic formations, including petroleum. 2 billion years ago the atmosphere had more co2 and less oxygen. Cyanobacteria changed the composition of the atmosphere. Humans also change the composition of the atmosphere. Burning fossil fuels, agricultural practices fossil fuels and deforestation. Direct measurement of co2 concentration in the atmosphere, 1950s to present. Annual fluctuations related to northern hemisphere seasons. Tree rings, ice cores, sediment cores, corals. Climate fluctuations in the past, but temperatures and the rate of change are increasing. Process by which gases in the atmosphere trap heat. Shortwave solar radiation (light) longwave radiation (heat) The greenhouse effect both natural and necessary.
