If you consider the classic Skeptical Science figure, something like 93% of the planetary energy imbalance is associated with heating the oceans, while only 3-4% is associated with heating the land and atmosphere (the rest is associated with the cryosphere). As a rough estimate the land and atmosphere has a mass of about 1019kg and a heat capacity of 1000 J kg-1 K-1. Therefore 1022J would increase the temperature of the land and atmosphere by 1K. The paper being discussed here suggests that the ocean heat has increased by about 3 x 1023J since pre-industrial times, with 50% occuring prior to 1997. If this is about 93% of all the energy accrued, then that implies a total of 3.2 x 1023 J, with 1.6 x 1023 J accruing before 1997, and an equal amount afterwards.
If we consider only the land and atmosphere, then prior to 1997 between 5 x 1021J and 6.4 x 1021J was accrued by the land and atmosphere (i.e., 3% – 4% of the total). Given its mass and heat capacity, this would have increased temperatures by between 0.5K and 0.65K. Looking at the Skeptical Science trend calculator, this looks quite reasonable.
However, given that this paper is suggesting a similar amount of energy was accrued after 1997 as before, we’d expect the amount of surface warming to be of a similar magnitude. However, it clearly is not. It’s warmed much less since 1997, than it did before 1997. So, based on this paper, it seems that global warming has indeed been accelerating, but that this has not manifested itself in the warming of the surface. If so, it does seem to confirm that surface warming can be quite variable, which is probably no great surprise. Could surface warming remain slow? Seems unlikely as you can’t keep accruing more and more energy in the oceans without the surface eventually catching up. Given that we may be about to have 3 warmest years in a row, we might be at the beginning of some kind of speed-up. Time will tell, though.
Anyway, I actually have to run now, so will leave it as is. Apologies if there are some errors and typos – I haven’t had a chance to proof-read this properly. Any clarifying comments or other thoughts welcome.