The study analyzes the variability of surface air temperature (SAT) and sea surface temperature (SST) obtained from a 1000-yr integration of a coupled atmosphere-ocean-land surface model, which consists of general circulation models of the atmosphere and oceans and a heat and water budget model of land surface. It also explores the role of oceans in maintaining the variability of SAT by comparing the long-term integration of the coupled model with those of two simpler models. They are 1 ) a “mixed layer model,” that is, the general circulation model of the atmosphere combined with a simple slab model of the mixed layer ocean, and 2) a “fixed SST model,” that is, the same atmosphere model overlying seasonally varying, prescribed SST. With the exception of the tropical Pacific, both the coupled and mixed layer models are capable of approximately simulating the standard deviations of observed annual and 5-yr-mean anomalies of local SAT. The standard deviation tends to be larger over continents than ... Abstract The study analyzes the variability of surface air temperature (SAT) and sea surface temperature (SST) obtained from a 1000-yr integration of a coupled atmosphere-ocean-land surface model, which consists of general circulation models of the atmosphere and oceans and a heat and water budget model of land surface. It also explores the role of oceans in maintaining the variability of SAT by comparing the long-term integration of the coupled model with those of two simpler models. They are 1 ) a “mixed layer model,” that is, the general circulation model of the atmosphere combined with a simple slab model of the mixed layer ocean, and 2) a “fixed SST model,” that is, the same atmosphere model overlying seasonally varying, prescribed SST. With the exception of the tropical Pacific, both the coupled and mixed layer models are capable of approximately simulating the standard deviations of observed annual and 5-yr-mean anomalies of local SAT. The standard deviation tends to be larger over continents than ...