Temperature trends in the middle atmosphere depend primarily on the trends in the radiatively active constituents (primarily CO2, ozone and H2O). Effects such as vertical coupling of radiative transfer (non-locality) and secondary absorption bands, however, have enough influence to render most regression analyses of temperature trends as a function of local constituent variations misleading. The role of these processes is demonstrated through an analysis of the factors affecting the modelled temperature response during the periods 1975 to 1995 and 2010 to 2040. These periods are characterized by differing rates of change in ozone and CO2 so that the various roles of the important radiative processes can be distinguished. The models used include the Canadian Middle Atmosphere Model (CMAM) simulation REF-B2 undertaken in support of the Chemistry Climate Model Evaluation effort and a one-dimensional radiative transfer model forced using appropriate globally averaged quantities from the CMAM run. In this paper, the processes of interest are introduced, the motivation for using the two time periods for this analysis outlined and the impact of the various processes on the temperature trend presented.