Snow is an important component of the Northern Hemisphere climate system. Persistent changes in snow accumulation resulting from climate change have the potential to yield ecological and economical consequences downstream via changes in melt water. In addition snow albedo feedback contributes to the real world climate sensitivity and the climate sensitivity of a given climate model. Previous attempts to determine an observational trend in snow cover extent have varied tremendously with the observational product. However, recent multi-data set results by Brown et al show a consistent long-term decrease seen during May and June, and variability which is strongly anti-correlated with temperature anomalies. I present preliminary results which compare the observational snow cover extent climatology, variability and trends with those from climate model simulations. The model data in this study is based on large ensembles (20 independent runs) of the Community Earth System Model, forced by historical concentrations of greenhouse gases and ozone during the period 1965-2010.