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climate5.10 - Climate Change Theories A. Most involve...

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Climate Change Theories A. Most involve FEEDBACK 2. Example: ice-snow-temperature feedback. To start, suppose something is able to cause colder temperatures to occur. with less radiation absorbed at the ground, we have colder temperatures, Once we have colder temperatures, we have more snow; with more snow, we have higher albedo; with high albedo, we have higher reflectivity; with high reflectivity, we have less radiation being absorbed at the ground; and the cycle keeps repeating. The surface gets colder and colder. 1. a change in a system that amplifies over time: A small initial change ends up making big change!
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A diagram of this feedback loop: Colder Temperatures   Snow  Higher Albedo  Higher Reflectivity  Less Radiation Absorbed  Colder Temperatures . .. and so on. So we don’t necessarily need to make BIG changes to change climate!
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Volcanic Dust Some such eruptions have produced veils of ashs and sulfuric acid aerosols that have spread worldwide in the stratosphere with lifetimes of two or more years. Because such volcanic veils scatter and absorb significant amounts of incoming solar radiation while having little effect on outgoing terrestrial radiation, they are capable of cooling worldwide climates by a fraction of °C over a period of years. In modern times, explosive volcanic eruptions like that of Krakatoa in 1883, violent enough to inject large amounts of fine ash and sulfurous gases into the midstratosphere (altitudes of 60,000 to 100,000 feet) have occurred with an average frequency of several per century.
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The 1815 eruption of Tambora was the largest eruption in historic time. About 150 cubic kilometers of ash were erupted (about 150 times more than the 1980 eruption of Mount St. Helens). Ash fell as far as 800 miles (1,300 km) from the volcano. In central Java and Kalimantan, 550 miles (900 km) from the eruption, one eruption by starvation, disease, An estimated 92,000 people were killed by the eruption. About 10,000 direct deaths were caused by bomb impacts, tephra fall, and pyroclastic flows.
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The Dust Veil Index (DVI) The DVI was devised by Lamb (1970) to provide a numerical assessment of the amount of volcanic dust injected into the stratosphere. Its value is based on the depletion of the direct solar
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This note was uploaded on 03/01/2011 for the course GPH 414 taught by Professor Cerveny during the Spring '10 term at ASU.

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climate5.10 - Climate Change Theories A. Most involve...

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