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Global WarmingGlobal Warming


Global warming is the slight but steady increase in the earth’s average temperature. It is natural and has happened before in the earth’s history. But recently global temperatures have become the highest ever recorded, causing some scientists to believe that the increase in greenhouse gasses, due to human activity, is affecting the earth’s climate.

Greenhouse gasses, which include water vapor, nitrous oxides, carbon dioxide, methane, and chlorofluorocarbons (CFCs), can be beneficial; they trap solar heat close to the earth’s surface, which keeps the earth warm. The concern among some scientists is that an increase in the amount of greenhouse gasses in the atmosphere will lead to an overheating of the earth. The earth’s surface temperature is predicted to rise between two to seven degrees Fahrenheit in the next century, which may not sound like much, but it is warmer than the earth has been in the last 10,000 years. Its average temperature has risen by about one degree in the past century, with much accelerated warming during the past two decades. This warming trend, according to these scientists, will also cause changes in precipitation, sea levels, wildlife habitat, and many other environmental factors. It has been predicted that one third of the world’s forests (both its flora and fauna) will be significantly affected by global warming.

Greenhouse gasses are increasing due to human activities. The amount of carbon dioxide in the atmosphere has increased due to the fossil fuels that are burned for factories, transportation, heating, and electricity. Since the Industrial Revolution, carbon dioxide in the atmosphere has increased by more than 30%.

The United States alone accounts for 23% of all carbon dioxide emissions caused by human activity. Methane has increased 151% due to agriculture and the use of fossil fuels. The use of aerosol propellants and refrigerants has caused an increase in the amount of CFCs in the atmosphere as well. Ozone holes, which are thin spots in the layer that protect the earth from radiation, are also attributed to increases in CFCs. Nitrous oxides in the atmosphere have increased 17% since the Industrial Revolution and are also a major cause of acid rain.

Global warming isn’t just an issue for icebergs and shorelines—it affects Indiana as well. The average temperature in Bloomington has increased 1.8° F during the last 100 years, and precipitation has increased 10%. Gary, Indiana, has been classified as having severe ozone and global warming problems due to extensive industrial pollution. These issues have a major effect on agriculture, which significantly influences the state’s economy. A 10% decrease in global crop yields would cause an extreme increase in world hunger and major changes in global economy.


Indiana Dept. of Environmental Management. "Global and Regional Air Quality." State of the Environment Report 2002. 28 Oct. 2002. <http://www.in.gov/idem/ soe2002/air/global.html>.

Miller, G. Tyler, Jr. Environmental Science: Working with the Earth. 8th ed. Pacific Grove, CA: Brooks/Cole, 2001.