What's global warming

Global warming is the observed increase in the average temperature of the Earth's atmosphere and oceans in recent decades and the projected continuation of rising temperatures. Models referenced by the Intergovernmental Panel on Climate Change (IPCC) predict that global temperatures are likely to increase by 1.1 to 6.4 °C (2.0 to 11.5 °F) between 1990 and 2100.[1] The uncertainty in this range results from both differing future greenhouse gas emission scenarios and uncertainties regarding climate sensitivity.

Also see Wikipedia on Global Warming