The uncertainties are large. The three main areas of uncertainty are detection of global warming, attribution of warming to greenhouse gases, and projecting future warming, Kerr writes.
Detection is probably the closest to being resolved of the three.
The IPCC puts warming at 0.6 degrees 0.2 degrees centigrade with a 95 percent confidence level. Attribution of global warming to anthropogenic emissions of greenhouse gases is much more difficult, however. Some modelers, such as Jerry Mahlman with NOAA and John Mitchell at the UK s Hadley Centre for Climate Prediction and Research, think the models are getting better. Tim Barnett of Scripps Institution of Oceanography and Jeffrey Kiehl of the National Center for Atmospheric Research concur. One of the primary means by which modelers have tweaked the models for better results is the inclusion of aerosols.