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