In 1986, a panel of 150 scientists from eleven countries issued a report warning that human activities such as automobile use, the production of energy from burning fossil fuels, and deforestation could cause global temperatures to rise by intensifying the earth's greenhouse effect. An essential component of the earth's climate, the greenhouse effect is the warming process that results from the atmospheric presence of heat-trapping gases such as water vapor, carbon dioxide, and nitrous oxide. Much of the solar energy that reaches the planet is absorbed by oceans and land masses, which in turn radiate the energy back into space. However, small concentrations of water vapor and other "greenhouse gases" convert some of this energy to heat and either retain it or reflect it back to the earth's surface. This "trapped" energy creates a blanket of warm air around the earth that moderates global temperatures and climate patterns. Without greenhouse...