Paper praising models’ predictions proves they greatly exaggerate

By Christopher Monckton of Brenchley,

A recent paper by Hausfather et al. purports to demonstrate that models “are accurately projecting global warming”. In reality, and stripped of the now-routine hype and editorializing with which the paper is riddled, the results plainly demonstrate precisely the opposite – that models have exaggerated global warming – and continue to do so.

Here is the “plain-language summary” of Evaluating the performance of past climate model projections, by Hausfather et al. (2019):

“Climate models provide an important way to understand future changes in the Earth’s climate. In this paper we undertake a thorough evaluation of the performance of various climate models published between the early 1970s and the late 2000s. Specifically, we look at how well models project global warming in the years after they were published by comparing them to observed temperature changes. Model projections rely on two things to accurately match observations: accurate modeling of climate physics, and accurate assumptions around future emissions of CO₂ and other factors affecting the climate. The best physics‐based model will still be inaccurate if it is driven by future changes in emissions that differ from reality. To account for this, we look at how the relationship between temperature and atmospheric CO₂ (and other climate drivers) differs between models and observations. We find that climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO₂ and other climate drivers. This research should help resolve public confusion around the performance of past climate modeling efforts, and increases our confidence that models are accurately projecting global warming.”

Fig. 1. Projections by general-circulation models (red) in IPCC (1990, 1995, 2001) and energy-balance models (green), compared with observed temperature change (blue) in Kelvin per decade, from surface temperature datasets only (Hausfather et al. 2019).

As Fig. 1 shows, the simple energy-balance models [such as Monckton of Brenchley et al. 2015] have done a much better job of prediction than the general-circulation models. In IPCC (1990), the models were predicting midrange warming of 2.78 or 0.33 K/decade. By 1995 the projections were still more extreme. In 2001 the projections were more realistic, though they have become still more extreme in IPCC’s 2006 and 2013 Assessment Reports. Terrestrial warming since 1990, at 1.85 K/decade, has been little more than half the rate predicted by IPCC that year:

Fig. 2. Terrestrial warming, 1990-2018 (mean of HadCRUT4, GISS and NCEI datasets). Even assuming the lesser of the two intervals of global-warming predictions in IPCC (1990), and even assuming that the terrestrial temperature record is not itself exaggerated, observed warming is scraping along the bottom of the interval.

Fig. 3. Lower-troposphere warming (UAH), 1990-2018, is well below even the lower bound of the models’ projections on which IPCC (1990) made its forecast of medium-term global warming.

Hausfather et al. make it appear that the models have been accurate in their projections by comparing the observed warming with the projection by the energy-balance model in IPCC (1990). However, IPCC based its original projections, as it does today, on the more complex and more exaggeration-prone general-circulation models:

Fig. 4. Were it not for the 2016 el Niño, IPCC’s original medium-term prediction, made in 1990, would be still more excessive than it is.

Notwithstanding the repeated exaggerations in the general-circulation models’ projections, exaggerations that Hausfather et al. have in effect sought to minimize, the modelers continue to flog the dead horse Global Warming by making ever more extreme projections:

Fig. 5. Charney-sensitivity projections in 21 models of the CMIP5 ensemble.

In 1979 Charney had predicted 2.4 to 3 K midrange equilibrium global warming per CO₂ doubling. IPCC (1990) chose the higher value as its midrange prediction. Now, however, the CMIP6 models are taking that midrange prediction as their lower bound, and their new midrange projection, shown above, is 4.1 K.

Since the warming from doubled CO₂ concentration is roughly the same as the warming to be expected over the 21^st century from all anthropogenic influences, today’s general-circulation models are in effect projecting some 0.41 K/decade of warming. Let us add that to Fig. 4 to show how excessive are the projections on the basis of which current policymakers and banks are refusing to lend to third-world countries for urgently-needed electrification:

Fig. 6. Prediction vs. reality, this time showing the implicit CMIP5 prediction.

Line-graphs such as Fig. 6 tend to conceal the true extent of the over-prediction. Fig. 7 corrects the distortion and shows the true extent of the over-prediction:

Fig. 7. Projected midrange Charney sensitivities (CMIP5 3.35 K, orange; CMIP6 4.05 K, red) are 2.5-3 times the 1.4 K (green) to be expected given 0.75 K observed global warming from 1850-2011 and 1.87 W m^–2 realized anthropogenic forcing to 2011. The 2.5 W m^–2 total anthropogenic forcing to 2011 is scaled to the 3.45 W m^–2 estimated forcing in response to doubled CO2. Thus, the 4.05 K CMIP6 Charney sensitivity would imply almost 3 K warming from 1850-2011, thrice the 1 K to be expected and four times the 0.75 K observed warming.

Though the analysis here is simple, it is just complicated enough to go over the heads of scientifically-illiterate politicians easily swayed by climate Communists who menace their reputations if they dare to join us in speaking out against the Holocaust of the powerless.

Let me conclude, then, by simplifying the argument. It is what is not said in any “scientific” paper about global warming that is most revealing. It is what is not said that matters. I cannot discover any paper in which the ideal global mean surface temperature is stated and credibly argued for.

The fact that climate “scientists” do not appear to have asked that question – or, as Sherlock Holmes would put it, that the dog did not bark in the night-time – demonstrates that the global-warming issue is political, not scientific.

The fact that the answer to that question is unknown demonstrates that there is no rational basis for doing anything at all about the generally warmer weather which is proving most beneficial where it is occurring fastest – in the high latitudes and particularly at the Poles.

There is certainly no case, scientific, economic, moral or other, for denying electrical power to the 1.2 billion who do not have it, and who die on average 15-20 years before their time because they do not have it.