Within the Paleoclimate Modeling Intercomparison Project, we have performed simulations of the present-day, mid-Holocene (MH), and Last Glacial Maximum (LGM) climates with two versions of the LMD (Laboratoire de M¿t¿rologie Dynamique, CNRS, Paris) atmospheric general circulation model which differ in their horizontal resolution and some parameterizations of the surface processes. This work focuses on the winter simulated climatic changes in northern midlatitudes, and we use energy budget analyses to diagnose the impact of the parameterizations on the climatic sensitivity. The dependency of the surface transfer coefficients on the air stability is shown to play a key role for the climatic sensitivity over regions of stable conditions: the northern Atlantic which is sea-ice covered at LGM, and the midlatitude continents during MH. For the MH we use a simple mathematical projection method to extract the climatic change signal from its interannual variability. ¿ 1998 American Geophysical Union