I don't think so. There are lots of other hockey sticks around -- for population, for energy use, for emissions. So how do they add together and what do they imply for temperature?
The hockey stick isn't a climate model, so it doesn't predict anything, but it's not really a surprising result, since the last few centuries had seen a super-exponential increase in human population, and at least an exponential increase in carbon dioxide, methane, nitrous oxide (N2O), etc.:
"Evidence for super-exponentially accelerating atmospheric carbon dioxide growth," Andreas D. Hüsler and Didier Sornette, http://arxiv.org/abs/1101.2832Surface temperature change is proportional to the rate of forcing change
ΔTs = λ ΔF
where λ is the climate sensitivity, or, for the change in time
CO2's forcing varies like the logarithm of the atmospheric concentration, and for CH4 and N2O it varies like the square root of the concentration.
If you do the derivatives
dF/dt = ∂F/∂C * ∂C/∂t + ...
and so on, with the past concentration (C) of CO2 changing super-exponentially (so the rate of forcing changes approximately exponentially), then surface temperature would have been changing exponentially too, seen over a couple of centuries.
Given these, the hockey stick's exponential rise in temperature, viewed over the last few centuries, is not especially surprising or unexpected.
|Radiative forcing is now rising linearly with time
Of course, this is just a heuristic argument. Doing the Mann et al. calculation is the only way to get the real function Ts(t). But it seems to me the sharp upward rise of the hockey stick circa 1850 - 1980 is not really surprising from a heuristic point of view. Given the laws of physics and the world's history of energy use, it would probably be more surprising if the hockey stick wasn't true.