I investigate the response of the present-day thermohaline circulation to a greenhouse gas induced global warming under different surface thermohaline conditions in a global Bryan/Cox <Bryan, 1969; Cox, 1989> ocean general circulation model with realistic bathymetry and geometry. Initially the model is spun up with surface temperature and salinity relaxed to Levitus <1982> climatologies. The forcing condition for salinity is then switched to a diagnosed flux, while that for temperature is provided by a restoration with a timescale of either 30 days (strong relaxation) or 300 days (weak relaxation). The present-day ocean climate is obtained under these two sets of thermohaline conditions. Under the strong restoration the modeled North Atlantic Deep Water Formation (NADWF) settles to an intensified state. Under the weak relaxation the model solution hardly differs from that of the spin-up. The ocean states are then subject to a global warming at a rate similar to that of the double CO2 experiment in a fully coupled model described by Manabe and Stouffer <1993, 1994>. The global thermohaline circulations under the weak relaxation show an initial weakening and shallowing, continued weakening upon the cessation of the atmospheric warming, and eventual reestablishment of their strengths. These behavior patterns are not unlike those found in the fully coupled model but are in sharp contrast to those in the case under the strong restoration, where NADWF eventually collapses. The processes responsible for these differences are discussed. ¿ American Geophysical Union 1996