Global Warming Essay

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Global Warming

Global warming is the progressive gradual rise of the earth's surface temperature thought to be caused by the enhanced greenhouse effect and responsible for changes in global climate patterns. The greenhouse effect is a term used to describe the roles of water vapor, carbon dioxide, and other trace gases in keeping the Earth's surface warmer than it would be otherwise.

These "radiatively active" gases are relatively transparent to incoming shortwave radiation, but are relatively opaque to outgoing longwave radiation. The latter radiation, which would otherwise escape to space, is trapped by these gases within the lower levels of the atmosphere. The subsequent reradiation of some of the energy back to the surface
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They have been used in refrigerators, air conditioners, plastic foams (bubbles) and aerosol cans. Water vapour is the most important greenhouse gas. Human activities are not directly changing the level of water vapour in the atmosphere. However, increases in other greenhouse gases are likely to raise the earth's temperature and thus increase evaporation and therefore the level of water vapour. This would further increase global warming.

There is an increasing body of evidence to suggest that global warming is taking place. Some examples include that temperature measurements taken in the traditional way - by thermometers in meterological stations - show that the world warmed by about 0.5 degrees celcius during the twentieth century, 1995 was the world's hottest year since reliable records began around 140 years ago - prior to this 1990 was the hottest year, The Australian Bureau of Meterorology records show that Australia has been warming since the early 1950 by 0.1 degrees celcius to 0.2 celcius a decade, five Antarctic ice shelves have retreated dramatically over the past 50 years and others have broken up, at Macquarie Island just north of Antarctica sea temperatures have risen by more than 1 degree celcius since 1912, pine trees in northern Finland have taken root in tundra areas at the rate of about 40 metres per year in an apparent response to warmer temperatures, tropical corals which are sensitive to water temperatures

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