This paper describes initial results from a broadscale study to assess decadal climate hindcast skills of the HadCM3, GFDL-CM2.1, NCAR-CCSM4, and MIROC5 global Earth System Models (ESMs) in experiments conducted under the Coupled Model Intercomparison Project 5. Analyses of decadal hindcast and simulation experiments using historical aerosol optical depths show statistically significant decadal predictability skill of global average and tropical sea surface temperature (SST) anomalies during 1961–2010. The skill, however, varies by averaging region and decade. It was also found that volcanic eruptions influence SSTs and are one of the sources of decadal SST hindcast skill. In the actual climate system, however, volcanic eruptions themselves are not predictable, and therefore, their effects on the climate system can only be predicted after eruptions. In the four ESMs utilized in this study, decadal hindcast skills of SST anomalies over ocean basin size averaging regions generally improve due to model initialization with observed data.