A coupled (ocean‐atmosphere) general circulation model (CGCM) and an uncoupled atmospheric general circulation model forced with the SST and external forcing of the coupled model simulate similar 2 m air temperature (TS) trends and also similar sea level pressure (SLP) trends for the latter half of the 20th century. This suggests that the inability of atmospheric models forced by observed SST and external forcing to reproduce observed SLP trends in the Indian Ocean could be due to model bias rather than lack of coupling. The internally generated TS trend in the CGCM is found to be small in comparison to the externally forced component. Intrinsic atmospheric noise explains most of the CGCM's internally generated high‐latitude SLP trend, while in low latitudes, the response of the SLP trend to the internally generated SST trend is important.