Welcome to the Climatic section of Geo-Earth. Here you will find the necessary links to different climate organizations. You can use the forum to discuss related topics, although free membership is preferred. A definition of climate can be found below:

The meteorological conditions, including temperature, precipitation, and wind, that characteristically prevail in a particular region.

Intergovernmental Panel on Climate Change: http://www.ipcc.ch/
National Oceanic and Atmospheric Administration (NOAA):  http://www.noaa.gov/climate.html
Paleoclimatology and Climate System Dynamics: http://www.agu.org/revgeophys/overpe00/overpe00.html
Climate Data Center: http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwAW~MP~F