From an analysis of observational data and general circulation model (GCM) simulations a review is given of the empirical parameterizations which lead to the occurrence of multiple equilibria in previously formulated energy balance climate models (EBM) of the Budyko-Sellers type. By drawing an analogy between the present-day southern hemisphere high-latitude conditions and the northern hemisphere (NH) high-latitude conditions during glacial times, we have devised a new parameterization for the zonal planetary albedo. In particular, we hypothesize that changes in the temperature of the NH polar regions can cause the development of a high-latitude planetary albedo anomaly (namely, the occurrence of continental ice sheets) and show that in this case a zonal mean EBM admits multiple equilibria. The zonal profiles of the climatic quantities for the warm and cold equilibrium states and their corresponding globally averaged values agree with the observational, geological, and paleoclimatic evidence and exhibit a poleward amplification of the temperature anomaly. The new parameterization of the ice albedo-temperature feedback introduces what we have called the thin ice cap instability (TICI). The TICI is a more realistic version of the Small Ice Cap Instability discussed in earlier versions of EBMs. The physical meaning the TICI and the sensitivity of the degree of nonlinearity it introduces to changes in the model parameters is then discussed. On the basis of modeling experience with a previously developed global EBM (to which the current EBM can be reduced by spatial integration), the stability of the equilibria is considered in terms of the Lyapunov pseudopotential. Finally, we perform time-dependent experiments to evaluate the relaxation time scales of the system around its equilibria and to investigate the latitudinal dependence of the response to perturbations. ¿ American Geophysical Union 1993