The Greenhouse Effect and Our Planet

The Greenhouse Effect and Our Planet

The Greenhouse Effect is what makes the earth habitable. Without water vapor, carbon dioxide, and other trace gases, too much heat would escape and the earth would probably be too cold to sustain life. The situation would resemble that on Mars, where there is little carbon dioxide and no water vapor. Although the increase in carbon dioxide shows no evidence that the earth will melt, there is a buildup of greenhouse gases (the enhanced greenhouse effect) usually referred to as simply "the greenhouse effect" (Stoyles18). Natural greenhouse gases include water vapor, carbon dioxide, nitrous oxide, methane, and ozone. The main gases that cause the enhanced greenhouse effect are carbon dioxide, methane, chlorofluorocarbons (CFC's) ozone and nitrous oxides.

Carbon Monoxide (CO) is a deadly poison when highly concentrated. As it rises into the atmosphere, it is converted into carbon dioxide. Carbon dioxide is a colorless, odorless gas that is produced when plant or animal matter and fossil fuels is burned. Carbon dioxide is the most important greenhouse gas.

Carbon dioxide held in the atmosphere is called "the air borne fraction". If the airborne fraction remains high, more carbon dioxide emitted into the atmosphere will stay there, and climate changes are likely to occur sooner than if the airborne fraction is low (Gay 22).

Methane is a colorless, odorless gas that is released during the processing of fossil fuels, and also comes from natural sources such as the rotting of plant matter and the stomachs of oxen, sheep, goats, and cows. Recently the dairy cows in California have been branded an environmental health risk because of the growing concern over the global impact of greenhouse gases produced by cattle and other livestock.

CFC's are compounds containing chlorine, fluorine, and carbon. CFC's are widely known as refrigerants, electronic cleaning agents, and are also found in foam and insulating products. Governments have decided to eventually discontinue production of CFC's, carbon tetrachloride, and methyl chloroform. Industry has developed "ozone-friendly" substitutes.

Ozone is near the ground (the troposphere) which is a major part of smog. The harmful ozone in the lower atmosphere should not be confused with the protective layer of the ozone in the upper atmosphere (the stratosphere), which screens out harmful ultraviolet rays. Ozone can lead to more frequent asthma attacks in people who have asthma and can cause sore throats, coughs, and breathing difficulties.

Nitrous oxides are produced by burning fossil fuels, most of which comes from power plants, motor vehicles, and trash burning.

Because of the harmful gases mentioned, there is an increased concern for global warming around the world. The rising temperature on earth is called global warming.

Rainforest destruction contributes to global warming. When trees are removed through clear-cutting or burning, the sudden warming of the forest floor releases methane and CO2. Each year deforestation contributes 23-30 percent of all carbon dioxide in the

atmosphere. Through photosynthesis, forests absorb and store so much atmospheric carbon that scientists refer to tropical rainforests as "Carbon sinks". Thus, while more and more carbon is released into the atmosphere, there are less and less forests to remove the carbon from the atmosphere. The plants and soil of tropical forests hold 460-575 billion metric tons of carbon worldwide with each acre of tropical forests storing about 180 metric tons of carbon (Urquhart).

Over the last century the average temperature has climbed above 1 degree Fahrenheit around the world (Handerk 10). Scientists believe that warmer and drier climates will decrease yields of three great American food crops; soybeans, wheat, and corn.

In the 1930's high temperatures and droughts plagued the Midwest in the United States, parts of Russia, and Southern Australia. Along with the warming climate, the ocean temperature rose and various species of fish usually found in Southern waters migrated much farther North than would be expected with today's climate (Gray 30).

Tiny animals called coral polyps build huge reefs in warm ocean water. Because of global warming, ocean water is heating up. If the water near a reef gets too warm, the polyps die. Then the once colorful reefs turn white. When a reef dies, fish and other creatures have to find new homes, or they will die too (Phelan 6).

Not only is there a concern for the coral reefs, but the animals in the sea are at risk. Several species could be lost forever, some of which have already become extinct.

Another impact of global warming is a rise in sea-level. One theory is that saltwater may intrude into rivers, streams, and ground water sources. If saltwater moves

into freshwater sources, entire ecosystems could be altered. Drinking water could be affected as well as flooding.

Precipitation is likely to increase regionally because as the temperature increases, more evaporation takes place, leading to more precipitation. This would mean: wetter monsoons in coastal regions; more frequent and heavier winter storms at high altitudes and latitudes; an earlier snowmelt and a wetter spring.

Scientists say that the effects of climate change are noticeable throughout the Arctic region. In Greenland, the largest island is thinning. In 2002-2003 a six mile stretch of the Sermeq Kujalleq glacier broke off and drifted towards Greenland's third largest town. The average ocean temperature off Greenland's west coast has risen in recent years, from 38.3 degrees Fahrenheit to 40.6 degrees Fahrenheit (Olson).

To date it has been difficult to note such an increase conclusively because of the differences in temperature around the Earth and throughout the year and because of the difficulty of distinguishing permanent temperature changes from the normal fluctuations of the Earth's climate. In addition, there is no universal agreement among scientists and climatologists on the potential impacts of an increase in the average temperature of the earth or other speculative issues covered in this thesis. Our ability to predict human influence on global climate is currently limited because the expected signal is still emerging from natural variability and the uncertainness of key factors. These include the patterns of long-term variability and the time-evolving pattern of nature and response to changes in concentrations of greenhouse gases and land surface changes.

All