søndag den 21. oktober 2007

Faster heating over the northern hemisphere

Global warming has great effect on crops and weather conditions around the world. The northern hemisphere contains more land area than the southern hemisphere, and conversely, a lower percentage of the world's oceans. Since oceans absorb more heat than land areas, it is not surprising that most climate models predict faster heating over the northern hemisphere than the global average. In addition, models predict faster temperature increases at higher latitudes. If global warming trends continue, high temperatures everywhere in the US may reduce US agricultural productivity. Northern continental areas are projected to have drier summer soils, due in part to earlier snow melts in the spring, and hotter, more cloudless summers, causing extensive evaporation of ground moisture. In addition, if the inland areas of the northern hemisphere are expected to receive less moisture, then, lake and river levels will be lower. Some reports predict the level of the Great Lakes will drop between 2 and 8 feet. River flows in the western US may be very vulnerable to increase temperatures expected as result of the greenhouse effect.

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