Very interesting section to the NASA Earth Observatory site (ie not a politician or celebrity or even unknown with an ax to grind) with all the famous graphs and global images used elsewhere. This is one of several chapters presented.
The most obvious impact of global warming will be changes in both average and extreme temperature and precipitation, but warming will also enhance coastal erosion, lengthen the growing season, melt ice caps and glaciers, and alter the range of some infectious diseases, among other things...Also see their section:
Predicting Future Warming (http://earthobservatory.nasa.gov/Library/GlobalWarmingUpdate/global_warming_update5.html)
