Guest essay by Christopher Monckton of Brenchley
Roger Taguchi, who often circulates fascinating emails on climatological physics, has sent me a beautifully simple and elegant demonstration that IPCC has at least doubled true climate sensitivity, turning a non-problem into a wolf-criers’ crisis. To assist in grasping the beauty of his brief but devastating argument, Fig. 1 shows the official climate-sensitivity equation:
Fig. 1 The official climate-sensitivity equation. Equilibrium or post-feedback sensitivity ΔTeq is the product of pre-feedback sensitivity ΔT0 and the post-feedback gain factor G.
Global temperature rose by 0.83 K from 1850-2016 (HadCRUT4: Fig. 2), while CO2 concentration rose from 280 to 400 ppmv. Officially-predicted pre-feedback sensitivity ΔT0 to this increase in CO2 concentration is thus 0.312 [5.35 ln (400/280)] = 0.60 K.
Even if CO2 were the sole cause of all the warming, the post-feedback gain factor G would be 0.83/0.60 = 1.38. Then, at doubled CO2 concentration and after all feedbacks had acted, equilibrium sensitivity ΔTeq would be only 0.312 x 5.35 ln (2) x 1.38 = 1.6 K.
Yet the AR4, CMIP3 and CMIP5 central equilibrium-sensitivity predictions are of order 3.2 K.
Not all feedbacks have acted yet. On the other side of the ledger, much of the global warming since 1850 is attributable either to natural causes or to other anthropogenic forcings than CO2. Netting off these two considerations, it is virtually certain that IPCC and the general-circulation models are overestimating Man’s influence on climate by well over double.
Fig. 2 The curve and least-squares trend of global mean surface temperature since 1850 (HadCRUT4).