Average temperature anomaly (standard base period): The 1930's and 40's vs. the 1980's and beyond.
These maps give some idea of the slower temperature response of the
oceans, due to their higher heat capacity. It takes much more energy to
warm the oceans even a fraction of a degree, and so the sea surface
doesn't warm as fast as the land masses. Since they cover most of
the planet, they retain and distribute a great deal of heat, producing a
lag between climate forcing and it's full atmospheric effect.