Carbon dioxide
This compound is a colorless, odorless, tasteless gas composed of one carbon atom and two oxygen atoms. Both natural and unnatural processes produce CO2. Animal respiration, decaying organic matter and certain underground natural features release CO2. Fossil fuel combustion also produces CO2.
Generally, carbon dioxide composes less than one percent of the air. In cities (because of the prevalence of carbonaceous combustion) this ratio is often higher. Currently, the worldwide level of CO2 and other greenhouse gases is growing: In 2005, the amount of carbon dioxide in the atmosphere was 35 percent higher than during the Industrial Revolution.
As carbon dioxide and other greenhouse gas levels rise, the atmosphere's greenhouse effect will increase, causing surface temperatures to warm up. Scientists predict temperatures will increase between 1.98-11.5 degrees Fahrenheit by 2099.
Sources:
-- "Carbon Dioxide," Columbia Encyclopedia on Infoplease.com. Accessed Sept. 24, 2007. http://www.infoplease.com/ce6/sci/A0810371.html
-- "Carbon Dioxide," EPA Web site. Accessed Sept. 24, 2007. http://www.epa.gov/climatechange/emissions/co2.html
-- "Earth's Atmosphere," Wikipedia. Accessed Sept. 24, 2007. http://en.wikipedia.org/wiki/Earth's_atmosphere
-- "The Physical Science Basis of Climate Change," Summary from the Intergovernmental Panel on Climate Change. Accessed Sept. 24, 2007. http://ipcc-wg1.ucar.edu/wg1/wg1-report.html
