This paper examines the range of uncertainty in our knowledge of the anthropogenic and natural radiative forcings since 1850. Simple climate models and an Intermediate General Circulation Model (IGCM) are used to crudely examine the likely effect of these forcings on the surface temperature trend. It is concluded from these experiments that any agreement between time-dependent global-mean surface temperature trends and surface temperature trends from GCM runs, which include only a few of these forcings, are probably only fortuitous, and as such the evolution of surface temperature in these experiments to not constitute a "detection of anthropogenic climate change"