The response of a coupled atmosphere-ocean general circulation model and an uncoupled atmosphere general circulation model to boundary conditions for 6000 years ago has been studied. The set of quasi-equilibrium simulations enables a separation of the contributions from changes in the ocean circulation, the CO2 concentration, and the insolation to the total response. The results indicate that all three factors have considerable impact on the climate change signal and here especially on the northern African and Indian monsoon. Multi-century adjustment processes associated with the inertia of the deep ocean play only a minor role for the climate change signal of the upper ocean and the atmosphere. ¿ 2001 American Geophysical Union