Consequences (1)

Global Warming



Increase of greenhouse gases concentration causes a reduction in outgoing infrared radiation, thus the Earth's climate must change somehow to restore the balance between incoming and outgoing radiation. This ¨climatic change〃 will include a ¨global warming〃 of the Earth's surface and the lower atmosphere as warming up is the simplest way for the climate to get rid of the extra energy. However, a small rise in temperature will induce many other changes, for example, cloud cover and wind patterns. Some of these changes may act to enhance the warming (positive feedbacks), others to counteract it (negative feedbacks).
Using complex climate models, the "Intergovernmental Panel on Climate Change" in their third assessment report has forecast that global mean surface temperature will rise by 1.4 to 5.8 by the end of 2100. This projection takes into account the effects of aerosols which tend to cool the climate as well as the delaying effects of the oceans which have a large thermal capacity. However, there are many uncertainties associated with this projection such as future emission rates of greenhouse gases, climate feedbacks, and the size of the ocean delay ...etc.



Sea Level Rise
If global warming takes place, sea level will rise due to two different processes. Firstly, warmer temperature cause sea level to rise due to the thermal expansion of seawater. Secondly, water from melting glaciers and the ice sheets of Greenland and the Antarctica would also add water to the ocean. It is predicted that the Earth's average sea level will rise by 0.09 to 0.88 m between 1990 and 2100.

It is unpredictable where the effect of the rise of the sea level will be the most tangible, as there are too many unknown elements. Generally speaking, however, there is a big chance that low-lying islands such as the Maldive Islands or atolls in the Pacific will disappear from the map. Elsewhere, harbours, cultural and historical sites by the sea and tourist beaches are in great danger. It is evident also that as the sea level rises, infrastructural works such as dikes, storm surge barriers, etc., will have to be modified.
Swamps and estuaries often play an important part in preventing floods. In addition, they are often characterised by a rich fauna and flora. If due to the rise of the sea level they remain flooded permanently, they will no longer be able to perform that drainage function and the survival of the entire biotope would be jeopardised.
River deltas for many countries are the places where the indispensable food is produced, and they stand a chance of disappearing. The most vulnerable among them are the Amazon, the Ganges, the Indus, the Mekong, the Mississippi, the Niger, the Nile, the Po and the Yangtze.