A simple model of climatic fluctuations in mean ocean temperature and latitudinal extent of sea ice (Saltzman, 1978) is investigated to determine the effects of nonlinearity and the initial state of the system. Solutions of the governing equations are analyzed as trajectories in a phase plane with coordinates corresponding to the sine of ice edge latitude &eegr; and mean ocean temperature ϑ. The model is found to be transitive for all physically plausible initial values such that all solutions go to ϑ0=278 ¿K and &eegr;0=0.885 as the time goes to infinity. The nonlinear term does not alter the qualitative nature of the model response to perturbations from the equilibrium values, which is characterized by damped linear oscillations about &eegr;0ϑ0. The distance from the model ice edge over which active melting or freezing is allowed determines the period and decay time constant for the oscillations. The plausible lower limit for this distance parameter leads to the freezing point in the ocean from seemingly reasonable initial values, but the modeling approximations cease to apply when ϑ reaches the freezing point. The model illustrates one of many possible modes of internal oscillations within the earth's climatic system.