We Live in a Greenhouse - Life on Earth depends on energy coming from the Sun. About half the light reaching Earth's atmosphere passes through the air and clouds to the surface, where it is absorbed and then radiated upward in the form of infrared heat. About 90 percent of this heat is then absorbed by the greenhouse gases and radiated back toward the surface, which is warmed to a life-supporting average of 59 degrees Fahrenheit (15 degrees Celsius).
Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are extremely likely due to human activities, and most of the leading scientific organizations worldwide have issued public statements endorsing this position. (Click here for a partial list of these public statements and related resources.)
Causes of Climate Change
Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2.