According to the National Academy of Sciences, the Earth’s average surface temperature has risen by about 1 degree Fahrenheit in the past century. There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide.
US EPA Climate Change web page
Emissions Comparisons of Greenhouse gases
North Carolina Division of Air Quality CO2 page
Greenhouse Gases and Global Warming information for Kids and Educators
