By Christopher Monckton of Brenchley

Recently the indefatigable Dr Willie Soon, who reads everything, sent me a link to the projections of equilibrium global warming in response to doubled CO₂. This standard yardstick for global-warming prediction is known in the trade as “Charney sensitivity” after Dr Jule Charney, who wrote a report in 1979 saying that doubled CO₂ would warm the world by 1.5-4.5 K, with a midrange estimate of 3 K. Most IPCC reports adopted the same sort of interval in making their predictions.

The Coupled Model Intercomparison Project’s 5th-generation models projected 2.1-4.7 K Charney sensitivity, with a midrange estimate of 3.35 K (from data in Andrews et al. 2012).

Now the sixth generation of these cybernetic behemoths, the CMIP6 ensemble predict 3 to 5.2 K Charney sensitivity, with a midrange estimate of 4.1 K (Fig. 1). The original midrange projection has become the lower bound.

Fig. 1. OTT: Projected Charney sensitivity in 21 CMIP6 models, September 2019.

In reality, the midrange Charney sensitivity to be expected on the basis of observed warming as well as total and realized forcing to 2011, the year to which climate data were updated in time for IPCC’s 2013 Fifth Assessment Report, is less than 1.4 K. That would take at least a century to happen.

Here, then, is a giant error of logic right at the heart of official climatology. CMIP5 models project 4.1 K warming in response to doubled CO₂ when, on the basis of officially-published data, they should be projecting only 1.4 K. They are overshooting threefold.

No surprise, then, that children relentlessly propagandized by the sub-Marxist educational establishment are either collecting Nobel Peace Prize nominations for making snarly faces at President Trump in the U.N. General Dissembly or committing suicide, as one Communized child did recently in the English Midlands, because “climate emergency”.

Teaching children about the ever-more-absurd hyper-predictions of global warming is child abuse. It should surely be outlawed before anyone else is driven to death. Unfortunately, the Socialist Party in Britain, which has been taken over by Communists in recent years, is proposing mandatory global-warming indoctrination classes even for five-year-olds.

Official climatology’s own mainstream data and methods would lead it to expect a midrange Charney sensitivity no more than one-third of the latest models’ 4.1 K projection.

We shall take the approach –revolutionary in climatology – of deriving the true midrange Charney-sensitivity estimate directly from real-world data. You don’t need models, except at the margins. It is possible to derive future global warming from the observed period warming from 1850-2011, from official estimates of the reference anthropogenic radiative forcing over the same period, and from the radiative imbalance that subsisted at the end of that period.

As far as I can discover the Intergovernmental Panel on Climate Change, to name but one, has never attempted to derive a midrange estimate of future global warming by that most obvious and direct method – from real-world data.

Fig. 2. Not much warming: Monthly temperature anomalies, 1850-2011 (HadCRUT4).

First, we need the warming ΔR₁ from 1850-2011. The answer, from HadCRUT4, the only global dataset that covers the whole period, is 0.75 K – at less than 0.5 K century^–1 (Fig. 2).

Next, we need the Planck sensitivity parameter P – the factor by which a radiative forcing is multiplied to yield the corresponding warming before accounting for feedback. Roe (2009) calls this pre-feedback warming the “reference sensitivity”.

A respectable approximation to P is the Schlesinger ratio (Schlesinger 1985), the ratio of the global mean surface temperature at a given moment to four times the net incoming radiative-flux density at the top of the atmosphere.

In (1), total solar irradiance S is 1363.5 W m^–2 (deWitte & Nevens 2017); albedo α is 0.29 (Stephens 2015); and the flat-Earth fudge-factor d is the ratio of the Earth’s spherical surface area to that of its great circle: i.e., 4. No allowance is made for Hölder’s inequalities between integrals (though it should be made), for we are using official climatology’s methods.

In (2), the Planck parameter P is derived on the basis that the global mean surface temperature T_S in 2011 was 288.4 K (HadCRUT4: Morice et al. 2012).

Knowing P gives us the reference sensitivity ΔR_C to doubled CO₂ in (3). I do not yet have the CO₂ forcing ΔQ_C from the CMIP6 models, so we shall take it as the mean of the estimates in 15 CMIP5 models (Andrews et al. 2012): i.e., 3.447 W m^–2.

Next, we need the reference (pre-feedback) anthropogenic radiative forcing ΔQ_ref from 1850-2011. IPCC (2013, fig. SPM.5) gives a midrange 2.29 W m^–2, to which subsequent papers (e.g. Armour 2017) have added 0.2 to correct an overestimate of the negative aerosol forcing. Call it 2.5 W m^–2.

We also need to know how much of that forcing has been realized: i.e., how much of it is reflected in the 0.75 K observed warming to 2011. Smith (2016) gives an estimated radiative imbalance, or unrealized forcing, of 0.6 W m^–2. Therefore, the realized forcing ΔQ_rlz is 2.5 – 0.6, or 1.9 W m^–2.

In (4), the system-gain factor A implicit in the real-world data from 1850-2011 is derived.

We can now derive the midrange estimate of Charney sensitivity ΔE_C in (5).

Fig. 4 shows the startling discrepancy between Charney sensitivity expected on the basis of observed warming, reference forcing and its realized fraction to 2011, on the one hand, and, on the other, and the untenably-exaggerated Charney sensitivities predicted by the CMIP models.

Fig. 4. Overstated midrange Charney sensitivities (CMIP5 3.35 K, red bar; CMIP6 4.05 K, purple bar) are 2.5-3 times the 1.35 K (orange bar) to be expected given 0.75 K observed warming from 1850-2011 (HadCRUT4: green bar), 2.5 W m^–2 total anthropogenic forcing to 2011 (IPCC 2013, fig. SPM.5; Armour 2017) and 0.6 W m^–2 unrealized forcing to 2010 (Smith 2015).

The models’ projections flatly contradict the published data on manmade forcing and radiative imbalance. Global warming will be about one-third of their overblown midrange estimates. Scientifically speaking, that ought to be enough to end the climate “emergency”.

Since three-quarters of the CMIP6 models’ midrange 4.1 K projection of Charney sensitivity is feedback response, the error in the models is likely to be in their treatment of the water vapor feedback. Indeed, the predicted tropical mid-troposphere “hot spot” predicted in model after model is not evident in observed reality (Fig. 5). Without it, the water vapor feedback response must be small, and could not quadruple reference sensitivities.

Fig. 5. Models’ projected tropical mid-troposphere “hot spot” (a) is not observed (b).

Policymakers, therefore, should assume a Charney sensitivity not of 3 or 4 K but of less than 1.4 K. Since that warming is small, slow and net-beneficial, and since climatology has never asked, let alone answered, the key question what is the ideal global mean surface temperature, there is no rational justification for assuming that a mild warming requires any action at all, except the courage to face down the screeching Communists and have the courage to do nothing.