We performed high resolution radiative transfer calculations to calculate the upward and downward long-wave radiation in the Arctic and Antarctica for the current atmospheric composition. In a previous study we observed the surprising finding of a negative Greenhouse Effect over Antarctica [ 1 ]. We now further developed the program to calculate the energy balance for every altitude level and the temporal development of the atmosphere. The calculations were performed every 3 hours for totally three years, giving the long-wave contributions for every atmospheric layer. The 'missing' contribution, the short wave radiation and contribution by advection, where considered by comparing the calculations with reanalysis data (ERA Interim). In an iterative process, necessary to consider the short- wave contribution and advection, we were able to simulate the seasonal variability of the atmosphere. In a next step we repeated the calculations by doubling CO 2 , CH 4 or H 2 O. Also, we studied the impact of the seasonal variability of CO 2 and the temperature. Results for both hemispheres will be presented and discussed.