The Effects of Global Warming

THE EFFECTS OF GLOBAL WARMING

"Global warming will be the greatest environmental challenge in the 21st century."

- Vice President, Albert Gore.

One of the most current and widely discussed factor which could lead to the ultimate end of existence of Earth and man is global warming and its devastating effects. Scientists have asked how fast the Earth is heating up, and how the warming effects on Earth may effect crops and climatic conditions. Several current trends clearly demonstrate that global warming is directly impacting on; rising sea levels, the melting of icecaps, and significant worldwide climatic changes. This paper will discuss the degree of destruction caused by global warming, contributing factors to warming, and finally, discuss what we can do to decrease the current rate of global warming. I would also like to present opposing viewpoints to the effects of the warming process. In my understanding, global warming represents a fundamental threat to all living things on earth.

WHAT IS THE "GREENHOUSE EFFECT" ALL ABOUT?

It is important to understand and discuss the significance of global warming. Global warming is also known as the "Greenhouse effect". The "Greenhouse Earth" is surrounded by a shield of atmospheric gases, rather than a glass or a plastic cover. The air that makes up our atmosphere consists primarily of nitrogen and oxygen molecules (N2 at 78% and O2 at 21%). A large number of "trace gases" make up the remainder of air's composition. Many of these, including carbon dioxide (CO2) and methane (CH4) are the so called "greenhouse" gases. If you have ever felt the piercing cold of the clear winter night sky and wondered why you feel warmer on a cloudy winter night, you have experienced the atmospheric greenhouse effect firsthand. Physics tell us that any object warmer than absolute zero will radiate energy. Cooler objects emit longer waves (in the infrared region) while hotter ones radiate shorter wavelengths. Our sun, powered by its hot, nuclear fusion reaction, produces radiant energy in the visible and ultraviolet regions with relatively short wavelengths. Of the sunlight that strikes the earth, about 70% is absorbed by the planet and its atmosphere, while the other 30% is immediately reflected. If the earth did not re-radiate most of this newly absorbed energy back into space the world would continue to get warmer. Instead, an energy balance is maintained.

The earth is about 60 degrees Fahrenheit (33 degrees Celsius) warmer than it would be if it did not have the atmospheric blanket of greenhouse gases and clouds around it. Clouds and greenhouse gases keep the earth warm. Once warmed, their molecules then radiate a portion of this heat energy back to earth, creating more warming on the surface of our planet. It is this radiation which causes atmospheric gases to move back to earth that scientists call the "greenhouse effect".

Carbon dioxide (CO2) gas generated by man's burning of fossil fuels and the forests is responsible for about half the greenhouse gas warming. Other gases (CFCs, methane, nitrous oxide, tropospheric ozone) are responsible for the rest. Increases in all these gases are due to mankind's explosive population growth over the last century, and increased industrial expansion. Approximately 80% of atmospheric CO2 increases are due to man's use of fossil fuels: oil, coal, and gas. These petroleum-based energy sources first came into use with the burning of coal during Since 1945 petroleum consumption has increased dramatically, due in large part to increased usage of automobiles worldwide, and the substitution of mechanized farm machinery for animal power. "Mankind is in the process of conducting a major, unintentional experiment, that of feeding back into the atmosphere in a short space of geological time the fossils fuels that have slowly accumulated over the past 500 million years." (Refer to graph #1)

Graph 1

Excluded

In 1958, scientists began to measure carbon dioxide levels in the atmosphere. The site selected for these measurements was on top of the volcanic mountain of Mauna Loa, in Hawaii. CO2 measurements at the Hawaiian site have continued. The instruments show the level of CO2 has been steadily increasing (about 0.4% per year) from a level of 315 parts per million (ppm) in 1958 to 353 ppm in 1990. Clearly, Earth's natural mechanisms for absorbing CO2 from the atmosphere cannot handle the large quantities of CO2 being added by modern man. Scientists believe nearly 1/2 of the CO2 being emitted each year remains in the atmosphere, while the rest is being absorbed by trees and the oceans. As a result, CO2 measurements show a continuing build-up of CO2 greenhouse gases in the air, gases that will eventually lead to more global warming. (Refer to graph #2)

Graph 2

HOW FAST IS THE EARTH HEATING UP?

Much debate in the last five years about the greenhouse effect has centered on interpreting temperature numbers generated at weather stations all over the world. The data from these thermometers are averaged and plotted in attempts to determine just how fast the earth has heated up since the measurements began. There is now no doubt the world is getting warmer. The thermometers show that the world is warmer now than at any time since the measurements started. The year 1990 was the hottest year in the last century. Together with 1991, the years of 1983, 1987, 1988, and 1989, have been measured to be the warmest 6 years in the last hundred years. 1991 was the second warmest year of the past century, perhaps due to the eruption of Mt. Pinatubo during that year. The ash from the volcano in the upper atmosphere blocks some sunlight to earth, and is expected to generate a temporary two or three year cooling effect. After that time, most ash particles will have settled back to earth, and most scientists expect to see the global warming trend continue.

According to scientists, we can with "99% confidence conclude that current temperatures represent a real warming trend rather than a chance fluctuation over the 30-year period." Most scientists agree that the planet's temperature has risen 0.5 degrees Celsius since 1900, and will continue to increase at an increasing rate. The environment is responding to this warming. For instance, a study of mountain plants in the Alps (Europe), shows that some cold-loving plants are starting to move to higher and cooler altitudes.