The oceans play a critical role in the storage of heat and carbon. When the surface of the earth is heated by the sun, the change in temperature is greater and faster on land than in the oceans. Because it is a fluid, the ocean diffuses the effects of a change in temperature over long distances.
One consequence of the ocean's ability to absorb more heat is that when an area of the ocean heats up more than normal, it takes much longer for that area to return to "normal" than it would for an area of land.
Therefore what we can expect is that although the ocean deceases the effects of the temperature change, if it gets to heat more than normal, it would be hotter than the earth.