GEOL 001 Lecture Notes - Lecture 30: Negative Feedback, Permafrost, Milankovitch Cycles
20 Dec 2020
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Document Summary
Active sun has more sunspots and releases more energy. Changes in shape of orbit and tilt of earth change amount of solar energy received. Milankovitch cycles - variations in solar radiation reaching earth due to variations in earth"s orbit. Cycles of glaciations during past 2 million years driven by milankovitch cycles. Configuration of continents determined by plate tectonics. Cause very gradual changes over tens of millions of years. Sulfur dioxide (so2) and ash from volcanoes. Volcanic sulfur dioxide (so2) in stratosphere will block and reflect some incoming solar radiation. Massive amount of so2 and ash injected into stratosphere. Worldwide temperature dropped 0. 5o c (~1o f) Caused the year without a summer in 1816. Gases in the atmosphere absorb infrared radiation (heat): Water - amount in atmosphere varies with climate. Methane - biological activity, melting permafrost, deep-sea methane hydrates. Cooling or warming causes other changes that reinforce cooling or warming. Cool climate means reduces vegetation, thus less is removed from atmosphere.
