A simple approach that considers both internal decadal variability and the effect of anthropogenic forcing is developed to predict the decadal components of global sea surface temperatures (SSTs) for the three decades 2011–2040. The internal decadal component is derived by harmonic wave expansion analyses based on the quasi-periodic evolution of the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO), as obtained from observational SST datasets. Furthermore, the external decadal component induced by anthropogenic forcing is assessed with a second-order fit based on the ensemble of projected SSTs in the experiments with multiple coupled climate models associated with the third Coupled Model Intercomparison Project (CMIP3) under the Intergovernmental Panels on Climate Change (IPCC) Special Reports on Emissions Scenario (SRES) A1B. A validation for the years from 2002 to 2010 based on a comparison of the predicted and the observed SST and their spatial correlation, as well as the root mean square error (RMSE), suggests that the approach is reasonable overall. In addition, the predicted results over the 50°S–50°N global band, the Indian Ocean, the western Pacific Ocean, the tropical eastern Pacific Ocean, and the North and the South Atlantic Ocean are presented.