Understanding the Greenhouse Effect

The greenhouse effect is produced as certain gases (water vapor, carbon dioxide, nitrous oxide, and methane, for example) allow incoming solar radiation to pass through the Earth's atmosphere but prevent most of the outgoing infrared radiation from the surface and lower atmosphere from escaping into outer space. This process occurs naturally and has kept the Earth's temperature about 60 degrees Fahrenheit warmer than it would otherwise be. Current life on Earth could not be sustained without the natural greenhouse effect.

However, the natural greenhouse effect is now being thrown out of balance. Human activities, especially the burning of fossil fuels, have increased the amount of carbon dioxide and other greenhouse gases in the atmosphere. Since the start of the industrial revolution, the amount of carbon dioxide in the atmosphere has increased 35 percent. The United States is the world's largest producer of greenhouse gases that cause global warming, producing 25% of worldwide emissions. Unlike most other pollutants, carbon dioxide stays in the atmosphere for hundreds of years. The accumulation of carbon dioxide intensifies the Earth’s natural heat-trapping “greenhouse effect.” Once the level of carbon dioxide is raised, it will stay raised - even if emissions were to cease immediately. Some continued warming is thus inevitable. However, the speed and amount of warming can be reduced if future greenhouse gas emissions are limited to stabilize the concentrations of greenhouse gases.