Carbon dioxide and methane (as well as other gases) in the atmosphere trap heat from the sun close to the Earth’s surface, warming the atmosphere. Combustion of fossil fuels is the largest anthropogenic, or man-made, source of carbon dioxide. From 1860 to 1994, carbon dioxide in the atmosphere rose from 280 to more than 350 parts per million. A network of scientists organized by the United Nations predicts that by 2100, if emissions are not reduced, global temperatures and sea levels will increase, islands and shorelines could be inundated, climate zones could shift, and weather could grow more turbulent. To address the issue of climate change, countries from around the world met in Kyoto, Japan in 1997 to develop a binding agreement to reduce carbon dioxide emissions from industrialized countries.

In this project, you will write 3–4 pages (not including title and reference pages) that examine the complex issue of global warming by addressing the following questions:

• What is the greenhouse effect, and how does it work?
• What are the main greenhouse gases?
• What is the present level of atmospheric carbon dioxide? Why has carbon dioxide concentration risen since 1860?
• What are some predicted environmental damages if carbon dioxide emissions are not reduced?
• In your analysis, how certain do we need to be about future predictions before acting on this problem?