David Appell spots a nice little calculation in the recently published Levitus 2012 paper on ocean heat content:
We have estimated an increase of 24 x 1022 J representing a volume mean warming of 0.09°C of the 0-2000 m layer of the World Ocean. If this heat were instantly transferred to the lower 10 km of the global atmosphere it would result in a volume mean warming of this atmospheric layer by approximately 36°C (65°F).
Holy cow! Thankfully and obviously this wont/can’t happen, as the authors quickly point out, but it does provide a startling example of how much extra energy has accumulated in the climate system, and how narrow a picture looking at the mean surface temperature really is.