Global warming is the increase in the average measured temperature of the Earth 's near-surface air and oceans since the mid-20th century, and its projected continuation.
http://en.wikipedia.org/wiki/Global_warming

Cooler Heads Coalition is an international group of non-profit organizations dedicated to smarter thinking on the subject of global warming and climate change
http://www.globalwarming.org/

The average surface temperature of earth has increased more than 1 degree Fahrenheit since 1900 and the rate of warming has been nearly three times the century-long average since ...
http://topics.nytimes.com/topics/news/science/topics/globalw ...

Official An Inconvenient Truth Global Warming Documentary Movie Site: Learn about Al Gore, Global Warming Truth, Causes, Effects & Facts, Climate Change, Greenhouse Gases and ...
http://www.climatecrisis.net/

The global warming controversy is a dispute regarding the nature and consequences of global warming. The disputed issues include the causes of increased global average air ...
http://en.wikipedia.org/wiki/Global_warming_controversy