Climate Fudge Factor Finally F**ked

— by Barry Brill, Chairman, NZ Climate Science Coalition

In a 2018 article “Human influence” is unquantifiable, I analysed the evidence offered by the IPCC for the most important conclusion of its AR5:

It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. – (WGI 10.3–10.6, 10.9)

This seminal opinion turned out to be based upon three justifications in Section, all of which turned out on inspection to be based on circular reasoning:

  1. Given that the anthropogenic increase in GHGs likely caused 0.5 °C to 1.3 °C warming over 1951-2010, with other anthropogenic forcings probably contributing counteracting cooling.
  2. The effects of natural forcings and internal variability are estimated to be small.
  3. Well-constrained and robust estimates of net anthropogenic warming are substantially more than half the observed warming (Figure 10.4).

The 0.5 – 1.3 °C range in i. comes from applying the assumed climate sensitivity range (1.5 – 4.5 °C) to the known level of anthropogenic increase in GHGs and then assuming that the entire DAGW hypothesis is correct.

As the observed warming trend over 1951-2010 is only 0.6 °C, it follows from this reasoning that sensitivity must be close to the bottom of the assumed range – i.e., about 1.6 °C. But this low sensitivity figure is completely unacceptable to the IPCC. It would indicate that AGW will never be “dangerous”, and thereby destroy the whole post-modern ‘climate change’ narrative.

Simplicity itself

So, Professor Phil Jones introduced his famous “fudge factor”, which assumes that anthropogenic aerosols will always reduce anthropogenic warming by the difference between the observed warming and the modelled warming. It consists of an additional batch of made-up assumptions as follows:

  • If sensitivity is 4.5 °C, then aerosol-induced cooling is 0.8 °C
  • If sensitivity is 4.0 °C, then aerosol-induced cooling is 0.6 °C
  • If sensitivity is 3.0 °C, then aerosol-induced cooling is 0.45 °C
  • If sensitivity is 2.0 °C, then aerosol-induced cooling is 0.3 °C
  • If sensitivity is 1.5 °C, then aerosol-induced cooling is 0.1 °C

Beautiful! No matter what temperature trend is actually observed, it can never disprove the ECS range adopted by the IPCC (actually borrowed from the 1979 Charney Report). If actual temperatures turn out to be much lower than modelled predictions, then the level of aerosols must be higher than expected. If modelled predictions are not scary enough, then just assume that the level of aerosols will drop and scale up the temperatures!

When you think about it, this fudge factor has had massive effects, in confounding the core of climate change science for the past two decades. Despite the millions of dollars poured into research, climate scientists have never been able to derive plausible figures for climate sensitivity. In consequence, they have never been able to produce actual evidence that the “enhanced greenhouse effect” is real and dangerous.

On the other side of the coin, sceptical scientists cannot disprove the hypothesis because the aerosol variable creates an equation that cannot be solved.

Just keep man-made aerosols secret

But the fudge factor, and all its ensuing confusion, depends crucially upon the actual level of human-caused aerosols remaining unknown.

Enter Professor Johannes Quaas, a meteorologist at Leipzig University, and colleagues from Europe, China and the US who have published1 robust observational evidence of the level of aerosol pollution. Writing in the journal Atmospheric Chemistry and Physics, Professor Quaas said:

We analysed data from NASA’s Terra and Aqua satellites. They have been providing comprehensive satellite observations of the Earth since the year 2000, measuring incoming and outgoing radiation, but also clouds and aerosol pollution. The latter has decreased significantly across North America, Europe and East Asia since 2000. Compared to the year 2000, it has led to an increase in the warming effect that is up to 50 per cent of the one by CO2 increases in the same period.

Science editor David Whitehouse points out that this relatively sudden drop in aerosol-induced cooling could well account for the increased global temperatures kicked off by the giant 2015-16 El Niño. If so, he concludes that the warming “hiatus” may not have ended yet:

When taken together with a couple of super-strong El Nino events which temporarily drove up global temperature (see graph …), the new findings suggest that the global warming hiatus — clearly evident prior to 2014 — may not have ended yet. If NASA’s satellite data are confirmed, it would suggest that much of the very moderate changes in global temperature this century may have been driven primarily by cleaner air and naturally-occurring El Ninos.

Although Dr Whitehouse expresses this view in tentative terms, it is hard to see how his hypothesis could be wrong, unless the Quaas paper is wrong.

If half of the observed 21st-century warming has been caused by aerosol reductions, then it obviously has not been caused by the observed increase in GHG forcing. Take away 50% of the current modest figures and the residual temperature trend is not statistically significant (i.e., it is less than the margin of error). That can only mean that the GHG-warming hiatus that commenced in 1997 continues.

The period 2012-15 saw a blizzard of research papers from IPCC lead authors explaining why a warming pause that lasted 10-15 years didn’t mean very much. There were none suggesting that a pause of 25+ years could be less than fatal for the credibility of climate models (or at least the 99% that assume an ECS higher than 2 °C).

The Quaas et al. paper is new and there has not yet been time for potential rebuttals or replication. But, if it holds up, it could make life very difficult for climate alarmists. As Dr Whitehouse notes:

The new observational data has strong implications for predictions of future global warming due to greenhouse gas forcing, suggesting it might be significantly lower than most models suggest.

We can be sure of one thing. The Quaas paper will inevitably bathe Phil Jones’ fudge factor in a very bright light – which has been lacking for the past quarter century. Can it survive such intense scrutiny?

It will surely be exposed as one of the great scandals of this already scandal-riven corner of public science.


Hits: 77

  1. Quaas et al. (2022) Robust evidence for reversal of the trend in aerosol effective climate forcing. Atmospheric Chemistry and Physics, 2022; 22 (18): 12221 DOI: 10.5194/acp-22-12221-2022

One Thought on “Climate Fudge Factor Finally F**ked

  1. Rickoshay on 21/11/2022 at 4:15 pm said:

    Yeh id have too call bullshiz on C02 induced warming full stop, just another scam from the same ppl that brought you C19, designed to decrease your wealth and complete control over your freedom via cdc,s and health passports.
    Best thing to do is leave the U.N. the wef and g20 fiascos once and for all, dump the who and repudiate agw all together, let the rest of the west go woke and broke, let them depopulate themselves whilst we just investigating the money trails in our own public office holders,
    plenty of evidence of Treason, Fraud and Crimes against Humanity to go around them all.

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