Over the 20th Century, the ocean has taken up the majority of excess heat due to global warming, twenty times as much as the atmosphere, and is projected to continue to do so in the 21st Century. Changes in ocean heat content in surface and deep layers are explored using results from historical 20th Century simulations and four future climate scenarios. The patterns of heat uptake are monotonic with increasing emission scenario. The majority of heat content changes on longterm time scales occur within the Atlantic and Southern Oceans. The future changes in the Atlantic Ocean can be attributed to a reduction in the strength of the Atlantic Meridional Overturning Circulation (AMOC), while future changes in the Southern Ocean are due to a poleward shift and strengthening of wind in this region. The AMOC and Southern Ocean overturning are two of the mechanisms that are thought to transport heat to the interior of the ocean on decadal timescales, which is thought to be responsible for the warming hiatuses; however, the forcing for these changes is likely different.