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Greenhouse Effect

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The natural greenhouse effect
The Earth's atmosphere is comparable to a glass roof of a greenhouse: the short-wave solar radiation passes through nearly unhindered and warms the Earth's surface. From the Earth's surface, the short-wave radiation is partly absorbed and partly reflected back as long-wave thermal radiation. However, this long-wave thermal radiation cannot pass the atmosphere unhindered due to the greenhouse gases but is partly reflected back again to the Earth's surface. In absence of this natural greenhouse effect the average temperature on the Earth would not reach the present level of about plus 15 degrees Celsius, but about minus 18 degrees Celsius.

The greenhouse gases are mainly water vapour, responsible for two thirds of the greenhouse effect, followed by carbon dioxide (CO2) with a share of approx. 15 percent, ozone with approximately 10 percent and nitrous oxide (N2O) and methane (CH4), each with a share of approx. 3 percent.

The anthropogenic greenhouse effect
The main reason for the anthropogenic greenhouse effect lies in the growing release of carbon dioxide primarily originating from an increasing energy consumption, and thus combustion of fossil energy sources.

In combustion processes, the carbon bonded in the fossil energy sources, which has been abstracted from the atmosphere over geological times, is released as carbon dioxide and concentrates in the atmosphere. This results in change of the atmospheric composition and thus increasing warming of the atmosphere.

Carbon dioxide (CO2) is the most significant greenhouse gas generating the anthropogenic greenhouse effect, and its 'contribution' amounts to about 50 percent. Also important, but on a smaller scale, are methane (CH4), ozone (O3) nitrous oxide (N2O) and hydrogenous fluorocarbons (HFC).

Consequences of the anthropogenic greenhouse effect
Accurate projections are very difficult due to the complexity of the processes in the worldwide climate. As a matter of fact the average temperature of the Earth's surface has increased by nearly 0.6 degree Celsius (over) the last 100 years. The most significant increase has been registered over the last 30 years.

Possible consequences could be:

  • Impact on the flora and fauna abundance of species-the increase of the global temperature will lead to a shift of climatic or vegetation zones which will then overtax the adaptability of the natural systems;
  • Increased frequency of extreme weather conditions.
  • Scarcity of water resources;
  • Melting of the polar ice-caps;
  • Rise of sea level;
  • Shift of marine currents and resulting regional climate changes;