Three scenarios for post-Kyoto emissions reductions indicate that ... the long-term consequences are small... The influence of the Protocol would, furthermore, be undetectable for many decades.

If you look at the attached plot you will see that the land also shows the 1940s blip (as I'm sure you know). So, if we could reduce the ocean blip by, say, 0.15 degC, then this would be significant for the global mean—but we'd still have to explain the land blip.