Analysis of observations and results from a global coupled climate model show that coherent decadal climate variability extends over the entire Pacific basin, is associated with processes in the Atlantic and Indian Ocean regions to contribute to global patterns of decadal climate variability, and encompasses regional decadal mechanisms noted in previous studies. Ocean heat content anomalies embedded in the gyre circulations of the Pacific, Atlantic and Indian Oceans are associated with global decadal timescale 'El Nino-like' signals in atmosphere and ocean with consequent global energy balance variations. Large-scale tropical-midlatitude interactions act to replenish the ocean heat content anomalies. Maxima in decadal timescale globally averaged surface temperature occur in conjunction with periodic arrangements of SST anomalies, in association with the heat content anomalies embedded in the various ocean gyre circulations, in a global 'El Nino-like' pattern that is highly correlated with such maxima. The decadal timescale in the model is approximately set by the circuit times of the ocean gyre circulations.