Global Warming Information

Greenhouse Gases
What's Being Done?
What Can I Do?

What is Global Warming?

Global warming is an observed increase in the average temperature of the Earth's atmosphere and oceans. Part of this increase may be due to natural processes, and would have occurred independently of human activity. The remainder is due to a human-induced intensification of the greenhouse effect. The increased volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing and agriculture, and other human activities, are the primary sources of human-induced warming. The natural greenhouse effect keeps the Earth about 33 °C warmer than it otherwise would be; adding carbon dioxide to an atmosphere, with no other changes, will make a planet's surface warmer.

Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth’s atmosphere. Sulfate aerosols, a common air pollutant, cool the atmosphere by reflecting light back into space; however, sulfates are short-lived in the atmosphere and vary regionally.