Manabe and Stouffer (1988) report two stable equilibria in a global coupled ocean–atmosphere model. The model, which includes general circulation models of the atmosphere and oceans and a simple land surface model, was integrated from two different initial conditions under identical boundary conditions. The two equilibria differ in the presence or absence of a thermohaline circulation in the North Atlantic. In one equilibrium, the North Atlantic has a vigorous thermohaline circulation with warm and saline surface water, while in the other, there is no thermohaline circulation and an intense halocline exists in the surface layer at high latitudes. The results suggest that the thermohaline circulation in the North Atlantic is responsible for the higher surface salinity in the northern North Atlantic compared to the northern North Pacific. The study also discusses the paleoclimatic implications of these results, particularly regarding the abrupt transition between the Alleröd and Younger Dryas events 11,000 years ago. The model was developed to study climate sensitivity to CO₂ forcing, and the results highlight the importance of thermohaline circulation in maintaining the observed water mass structure of the Atlantic Ocean. The study also shows that the two equilibria are stable and distinct, with the presence or absence of thermohaline circulation affecting surface salinity and temperature. The results suggest that the coupled system may have at least two stable equilibria, with the thermohaline circulation playing a key role in determining surface salinity and temperature. The study also discusses the mechanisms that maintain these equilibria and their geophysical significance. The model was found to have a global domain, realistic geography, and annually averaged insolation. The atmospheric component of the model uses a semispectral method for dynamic computation, while the oceanic component uses primitive equations of motion. The model was integrated asynchronously, with the atmospheric and oceanic components integrated over different periods. The results show that the two equilibria are stable and distinct, with the presence or absence of thermohaline circulation affecting surface salinity and temperature. The study also discusses the role of the Mediterranean outflow in the formation of North Atlantic deepwater and the budget analysis of heat and water in the oceans. The results suggest that the thermohaline circulation is essential for maintaining the observed surface salinity and temperature in the North Atlantic. The study also highlights the importance of the thermohaline circulation in determining the climate of the North Atlantic and its role in the abrupt climate transitions of the past.Manabe and Stouffer (1988) report two stable equilibria in a global coupled ocean–atmosphere model. The model, which includes general circulation models of the atmosphere and oceans and a simple land surface model, was integrated from two different initial conditions under identical boundary conditions. The two equilibria differ in the presence or absence of a thermohaline circulation in the North Atlantic. In one equilibrium, the North Atlantic has a vigorous thermohaline circulation with warm and saline surface water, while in the other, there is no thermohaline circulation and an intense halocline exists in the surface layer at high latitudes. The results suggest that the thermohaline circulation in the North Atlantic is responsible for the higher surface salinity in the northern North Atlantic compared to the northern North Pacific. The study also discusses the paleoclimatic implications of these results, particularly regarding the abrupt transition between the Alleröd and Younger Dryas events 11,000 years ago. The model was developed to study climate sensitivity to CO₂ forcing, and the results highlight the importance of thermohaline circulation in maintaining the observed water mass structure of the Atlantic Ocean. The study also shows that the two equilibria are stable and distinct, with the presence or absence of thermohaline circulation affecting surface salinity and temperature. The results suggest that the coupled system may have at least two stable equilibria, with the thermohaline circulation playing a key role in determining surface salinity and temperature. The study also discusses the mechanisms that maintain these equilibria and their geophysical significance. The model was found to have a global domain, realistic geography, and annually averaged insolation. The atmospheric component of the model uses a semispectral method for dynamic computation, while the oceanic component uses primitive equations of motion. The model was integrated asynchronously, with the atmospheric and oceanic components integrated over different periods. The results show that the two equilibria are stable and distinct, with the presence or absence of thermohaline circulation affecting surface salinity and temperature. The study also discusses the role of the Mediterranean outflow in the formation of North Atlantic deepwater and the budget analysis of heat and water in the oceans. The results suggest that the thermohaline circulation is essential for maintaining the observed surface salinity and temperature in the North Atlantic. The study also highlights the importance of the thermohaline circulation in determining the climate of the North Atlantic and its role in the abrupt climate transitions of the past.