, an increase in the average temperature on Earth, is getting worse. The Earth has warmed 0.3 to 0.6 degrees Celsius since the late 1800s. Scientists believe that the cause is the greenhouse effect, the process of trapping heat in the Earth's atmosphere because of the presence of large amounts of carbon dioxide, chlorofluorocarbons, methane, and nitrogen oxides. Less oxygen is being produced and cleaning the atmosphere allowing more of these gases to do its work on the environment. Automobiles exhausts are just one of the contributors to ....