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Global Change Essay

Decent Essays

Global Change

Introduction:

Global Change is a new mutli-disciplinary science which seeks to understand the various ways the environment is being altered by man's activities. The mechanisms of change are referred to as anthropogenic forcings and are usually involved with atmospheric alteration or land-use changes. The atmosphere is being altered by the addition of many chemicals including carbon dioxide, oxides of nitrogen, sulfur compounds, halogen compounds and various aerosols. Land-use changes include habitat fragmentation, conversion to agricultural uses and biome conversion from introduced exotic species. As the human population continues to expand it puts increasing pressure on ecosystem services (Cairns, 1996). Ecosystem …show more content…

The atmosphere is heated by sunlight. That heat is captured by individual gas molecules. Increasing the number of molecules able to store heat is believed to increase the total amount of heat stored. Different molecules have different heat storage capacities. Curiously the most important gas for heat retention in the atmosphere is water vapor. Water vapor is however not a direct concern for global warming researchers as man does not directly influence the concentration of water vapor in the atmosphere and water vapor returns to the Earth very quickly after evaporation. The gases of concern are anthropogenically introduced and remain in the atmosphere for long periods of time allowing their concentrations to build up. The most important of these are carbon dioxide, methane and nitrous oxide which can remain in the atmosphere for 50-200, 10 and 150 years respectively (Berner, 1994). Current information is maintained by the U.S. Department of Energy at the Carbon Dioxide Information Analysis Center, where David Keeling's original data can be viewed.

Ozone Depletion

In 1986, three british scientists published a landmark article in the journal Nature showing wide yearly fluctuations in stratospheric ozone over the Antarctic. Statospheric ozone is responsible for most of the atmosphere's absorption of UV-B radiation. UV-B radiation degrades DNA which can induce many forms of cancer. The ozone hole over the Antarctic is derived from a complex mixture of

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