Abstract
For a given value of the solar constant we have found that the Budyko-type climate model gives two positions for the edge of the polar ice sheet. The results of the Budyko model suggest that with a decrease in the solar constant of about 1.6%, the ice cap reaches a latitude of about 50°. At this point the model breaks down and the solution for the position of the edge of the polar ice sheet becomes complex. We have based our conclusions on analytic investigations. Numerical calculations were used only to support our analytic results.