| It is important to understand the significance that global | | | | trend continue. According to scientists, we can with |
| warming has on not only our earth, but our daily lives | | | | "99% confidence conclude that current temperatures |
| as well. It's also important to understand the effects of | | | | represent a real warming trend rather than a chance |
| global warming that our children and grandchildren will | | | | fluctuation over the 30-year period." Most scientists |
| experience in the years to come if things continue the | | | | agree that the planet's temperature has risen 0.5 |
| way they are now. First, it's important to understand | | | | degrees Celsius since 1900, and will continue to |
| that "Global Warming" is also known as the | | | | increase at an increasing rate. The environment is |
| "Greenhouse effect". Instead of a plastic or glass | | | | responding to this warming. For instance, a study of |
| shield, the earth has around it a series of atmospheric | | | | mountain plants in the Alps (Europe), shows that some |
| gases consisting mostly of nitrogen and oxygen | | | | cold-loving plants are starting to move to higher and |
| molecules. The earth is about 60 degrees Fahrenheit | | | | cooler altitudes. That is a possible response to |
| warmer than it would be if it didn't have those | | | | increasing temperatures. The global effects of the |
| atmospheric gases surrounding it. They keep the earth | | | | greenhouse effect cannot be directly predicted simply |
| warm and protected from excess UV (Ultra Violet) | | | | because we do not have enough knowledge in the |
| rays from the sun. Once warmed, their molecules then | | | | subject. However, we have been able to draw direct |
| radiate a portion of this heat energy back to earth, | | | | connections between certain natural phenomenon that |
| creating more warming on the surface of our planet. It | | | | supports the idea that something is changing. Global |
| is this radiation which causes atmospheric gases to | | | | warming has great effect on crops and weather |
| move back to earth that scientists call the | | | | conditions around the world. The northern hemisphere |
| "greenhouse effect". Much debate in the last five | | | | contains more land area than the southern hemisphere, |
| years about the greenhouse effect has centered on | | | | and conversely, a lower percentage of the world's |
| interpreting temperature numbers generated at | | | | oceans. Since oceans absorb more heat than land |
| weather stations all over the world. The data from | | | | areas, it is not surprising that most climate models |
| these thermometers are averaged and plotted in | | | | predict faster heating over the northern hemisphere |
| attempts to determine just how fast the earth has | | | | than the global average. In addition, models predict |
| heated up since the measurements began. There is | | | | faster temperature increases at higher latitudes. If |
| now no doubt the world is getting warmer. The | | | | global warming trends continue, high temperatures |
| thermometers show that the world is warmer now | | | | everywhere in the US may reduce US agricultural |
| than at any time since the measurements started. The | | | | productivity. Northern continental areas are projected |
| year 1990 was the hottest year in the last century. | | | | to have drier summer soils, due in part to earlier snow |
| Together with 1991, the years of 1983, 1987, 1988, and | | | | melts in the spring, and hotter, more cloudless |
| 1989, have been measured to be the warmest 6 | | | | summers, causing extensive evaporation of ground |
| years in the last hundred years. 1991 was the second | | | | moisture. In addition, if the inland areas of the northern |
| warmest year of the past century, perhaps due to the | | | | hemisphere are expected to receive less moisture, |
| eruption of Mt. Pinatubo during that year. The ash from | | | | then, lake and river levels will be lower. Some reports |
| the volcano in the upper atmosphere blocks some | | | | predict the level of the Great Lakes will drop between |
| sunlight to earth, and is expected to generate a | | | | 2 and 8 feet. River flows in the western US may be |
| temporary two or three year cooling effect. After that | | | | very vulnerable to increase temperatures expected as |
| time, most ash particles will have settled back to earth, | | | | result of the greenhouse effect. |
| and most scientists expect to see the global warming | | | | |