Clarifying the Greenhouse Effect. What is the Science Behind the Rhetoric?

      The greenhouse effect is a term that refers to the accumulation of carbon dioxide, water vapor and other greenhouse gases in the Earth’s atmosphere.  These gases in the atmosphere absorb reflected infrared radiation and re-reflect it back towards Earth causing the atmosphere to behave like a greenhouse. The greenhouse effect maintains a fairly consistent temperature on Earth, allowing life as we know it to exist. Unfortunately, during the last 150 years, the carbon dioxide content in the atmosphere has increased rapidly. Campbell and others (2008) state “Global models predict that by the end of the 21^st century, the atmospheric carbon dioxide concentration could more than double, increasing the average global temperature by about 5 degrees Celsius” (pg 1240). The increasing level of CO₂ in the atmosphere is most likely caused by excessive burning of fossil fuels. According to the EPA, “An unequivocal warming trend of about 1.0 to 1.7 degrees Fahrenheit occurred from 1906 to 2005 in both the Northern and Southern Hemispheres and over the oceans” (p 1). This effect is known as global warming.

     The rise in the Earth’s temperature due to global warming and the accumulation of carbon dioxide in the atmosphere may have negative effects on the environment, agriculture and health. According to Campbell and others (2008), the increased levels of carbon dioxide in the environment may cause increased productivity in plants which may cause certain plants to grow in areas where they would not normally thrive (p 1240). Another effect of global warming which has already been documented in the northern coniferous forests and tundra is the significant decrease in snow and ice cover. Arctic sea ice, as measured in 2007, covered the smallest area on record. The decreasing habit available for animals such as the polar bear, seals and seabirds may cause them to become endangered (p 1241). If the earth continues to warm as scientists predict, some agricultural areas in the mid-western United States would become much drier, reducing crop production and available feed for livestock. A study by Gualdi and others (2008) showed that global warming may cause an increase in tropical cyclone activity. Increased rainfall in areas affected by the cyclones could cause severe flooding to towns and farmland (p 5204).  According to Campbell and others (2008), another side effect of the pollutants in the Earth’s atmosphere is the thinning of the ozone layer which protects the Earth from harmful ultraviolet radiation. Studies show that the ozone layer has been thinning since 1975. The release of chlorofluorocarbons into the atmosphere from chemicals used in refrigeration and manufacturing is the main cause of the thinning of the ozone layer. The increase of the amount of UV rays which reach the Earth’s surface may lead to a rise in the rate of skin cancer and other related conditions (p 1241).

     On May 19, 2009, President Obama announced a national fuel efficiency policy. According to the EPA, the purpose of this policy is to decrease the amount of greenhouse gases entering the atmosphere by increasing the fuel efficiency of new cars and trucks.  Obama’s plan could save almost two million barrels of oil while the program is in effect, reducing greenhouse gas emissions by 900 million metric tons.  President Obama also announced new guidelines for mountaintop coal mining which should minimize damage to the surrounding environment. The plan will be implemented by the end of 2009.             

Cited References

Campbell NA, Reece JB. 2008. Biology. San Francisco: Pearson Benjamin Cummings. 1240-1241p.

Gualdi S, Scoccimarro E, and Navarra A. 2008. Changes in tropical cyclone activity due to global warming: results from a high-resolution coupled general circulation model. American Meteorological Society. In: Journal of Climate [internet]. c2008 [cited 2009 June 14]. Available from: www.ebscohost.com.

State of Knowledge [online article]. [2 pages]. In: Environmental protection agency state of knowledge. c2009 [cited 2009 June 14]. Available from: www.epa.gov/climatechange/science/stateofknowledge.html.