For the past two or three decades, several national meteorological services and universities have been running global climate models (GCM) which project future climatic regimes. In recent years the IPCC Task Group on Scenarios for Climate Impact Assessment (TGCIA) has made recommendations regarding the output from GCMs, and for the use of this output in climate change impacts studies. These specifications include such parameters as the time frames for model predictions, the atmospheric GHG concentrations, etc. 

Climate change scenarios constructed from many of the major international GCM output data sets can be viewed at the Canadian Climate Impacts Scenarios web site http://www.cics.uvic.ca/scenarios/ hosted by the Canadian Institute for Climate Studies at the University of Victoria, Victoria.