A previous study of blocking characteristics in an increased CO2 environment indicated that blocking events in the Northern Hemisphere would occur more often, but would be less persistent and less intense that their present-day counterparts. The current study re-examines this issue using two recent global blocking climatologies, and a control and increased CO2 run generated by the Institute of Numerical Mathematics General Circulation Model. The current study improves upon the earlier study in several important ways. The current study includes; an analysis of Southern Hemisphere blocking events, two long-term climatologies as the basis for observational comparison, includes model runs that simulate interannual variability due to, for example, El Nino and Southern Oscillation, and incorporates a gradual increase in the CO2 concentration in a linear fashion. Initial results demonstrate that for the Hemisphere, the new results improve upon the previous study in the following manner. For the Southern Hemisphere, initial results demonstrate…….