A global coupled ocean-atmosphere model of intermediate complexity is used to simulate the equilibrium climate of both today and the Last Glacial Maximum, around 21,000 years ago. The model successfully predicts the atmospheric and oceanic circulations, temperature distribution, hydrological cycle and sea-ice covet of both periods without using ＇flux adjustments＇. Changes in oceanic circulation, particularly in the Atlantic Ocean, play an important role in glacial cooling.