The influence of transient surface fluxes on North Atlantic overturning in a coupled GCM Climate Change Experiment

The mechanism by which the model‐simulated North Atlantic thermohaline circulation (THC) weakens in response to increasing greenhouse gas (GHG) forcing is investigated through the use of a set of five multi‐century experiments. Using a coarse resolution version of the GFDL coupled climate model, the role of various surface fluxes in weakening the THC is assessed. Changes in net surface freshwater fluxes (precipitation, evaporation, and runoff from land) are found to be the dominant cause for the model's THC weakening. Surface heat flux changes brought about by rising GHG levels also contribute to THC weakening, but are of secondary importance. Wind stress variations have negligible impact on the THC's strength in the transient GHG experiment.

[1]  U. Mikolajewicz,et al.  The role of the individual air-sea flux components in CO2-induced changes of the ocean's circulation and climate , 2000 .

[2]  A. Weaver,et al.  On the sensitivity of projected oceanic thermal expansion to the parameterisation of sub‐grid scale ocean mixing , 1999 .

[3]  A. Weaver,et al.  On the sensitivity of global warming experiments to the parametrisation of sub-grid scale ocean mixing , 1999 .

[4]  Stefan Rahmstorf,et al.  Long-Term Global Warming Scenarios Computed with an Efficient Coupled Climate Model , 1999 .

[5]  John R. Lanzante,et al.  Global mean surface air temperature and North Atlantic overturning in a suite of coupled GCM climate change experiments , 1999 .

[6]  Thomas F. Stocker,et al.  The Stability of the Thermohaline Circulation in Global Warming Experiments , 1999 .

[7]  S. Manabe,et al.  Transient response of a coupled model to estimated changes in greenhouse gas and sulfate concentrations , 1997 .

[8]  Syukuro Manabe,et al.  Interdecadal Variations of the Thermohaline Circulation in a Coupled Ocean-Atmosphere Model , 1993 .

[9]  Syukuro Manabe,et al.  Transient responses of a coupled ocean-atmosphere model to gradual changes of atmospheric CO2 , 1991 .

[10]  J. Houghton,et al.  Climate change 1995: the science of climate change. , 1996 .

[11]  Syukuro Manabe,et al.  Multiple-Century Response of a Coupled Ocean-Atmosphere Model to an Increase of Atmospheric Carbon Dioxide , 1994 .

[12]  J. Houghton,et al.  Climate change 1992 : the supplementary report to the IPCC scientific assessment , 1992 .

[13]  S. Manabe,et al.  Interhemispheric asymmetry in climate response to a gradual increase of atmospheric CO2 , 1989, Nature.