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