Kenneth Green

About the author: Kenneth Green is director of the environmental program at Reason Public Policy Institute, a nonprofit research organization headquartered in Los Angeles, California.

Certain atmospheric gases—such as carbon dioxide, methane, ozone, and nitrous oxide—trap solar energy and keep the temperature of the earth warmer than it would be without such gases. This "greenhouse effect" is beneficial because it has allowed life to proliferate on the planet. However, the levels of some greenhouse gases have increased since the late 1700s, causing a rise in the average global temperature. Some scientists maintain that human industrial activities are elevating concentrations of heat-trapping gases, and that the resultant global warming could lead to catastrophic climatic change. Other researchers dispute the theory that global warming is caused by human activity and contend that there is no evidence...