Global Greenhouse effect by Geoff Anthony The global effects of the greenhouse effect cannot be directly predicted simply because we do not have enough knowledge in the subject. However, we have been able to draw direct connections between certain natural phenomenon that supports the idea that something is changing. 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. When many people think of global warming, their first concern is the possible rise of sea levels. With a large number of the world's cities in coastal areas, this is a significant problem. There are two major causes of rising sea levels. First, extra water is produced when ice melts. Secondly, the natural expansion of sea water as it becomes warmer. The range of sea ice around both poles continues to shrink, as it melts. Even with the level of greenhouse gases present today, the earth may warm enough in the next 50 years or so to completely melt the sea ice located on the poles. Damage from rising seas is very diverse. Buildings and roads close to the water could be flooded and they could suffer damage from hurricanes and tropical storms. "There are good physical reasons to suggest that more intense storms (hurricanes) could result from global warming." Warmer oceans cause more intense storms. Experts believe that global warming could increase the intensity of hurricanes by over 50 percent. Hurricane Andrew's devastation in 1992 set new records. According to the National Hurricane Center in Miami, the 1990 season was the most active year on their records for combined Atlantic and Pacific hurricanes. Damage caused by future hurricanes to populated areas will be more severe since higher sea levels are predicted for the next century. In addition, as the sea rises, beach erosion takes place, particularly on steep banks. Wetlands are lost as sea levels rise. Another serious problem is the threat of salt water intruding into underground fresh water reserves in coastal areas. College of New Caledonia -CNC ion 4