The Global Modeling Initiative (GMI) 3-D chemistry and transport model has been used to generate 2 simulations of the 2000-2030 time period. The 30-year simulations both used the source gas and aerosol boundary conditions of the 2002 World Meteorological Organization assessment exercise MA2. The first simulation was based on a single year of meteorological data (winds, temperatures) generated by the new Goddard Space Flight Center “Finite Volume” General Circulation Model (FVGCM), repeated for each year of the simulation. The second simulation used a year of meteorological data generated by a data assimilation system based on the FVGCM, using observations for July 1, 1999 – June 30, 2000. We intercompare the two representations of the current atmosphere at the poles, and examine the predicted impacts of changing source gas emissions on the photochemistry of the polar regions, particularly during the winter.