A two-dimensional, seasonal, energy balance climate model with continents and ice sheets: testing the Milankovitch theory

A simple seasonal, two-dimensional, energy balance climate model that contains an ice sheet model is forced by varying the orbital parameters. If a mechanism that enhances melting during ice sheet retreat is introduced, variations in ice volume resembling those deduced from oxygen isotope variations are predicted. Since the Milankovitch theory asserts that cool high latitude summers lead to the growth of ice sheets, a seasonal climate model with continents must be used to test the theory. An ice sheet model must also be included because the presence of an ice sheet leads to a large amplification of its own size. When all three of these ingredients are present in the model, very large ice sheets can be produced. A strong 100 kyr cycle is present only if a mechanism that enhances ice sheet collapse is introduced. Other predicted features of past climate variations, such as ocean temperature and sea ice variation, also resemble paleoclimate reconstructions from proxy data.