Ridley trots out a combination of long-refuted myths that are much loved by contrarians; bad or crank science; or misunderstandings as to the current state of knowledge. In the absence of a Climate Feedback dissection of Ridley’s latest opinion piece, here is my response to some of his nonsense …

Here are five statements he makes that I will refute in turn.

1. He says: Forty-five years ago a run of cold winters caused a “global cooling” scare.

I say:

Stop repeating this myth Matt! A few articles in popular magazines in the 70s speculated about an impending ice age, and so according to dissemblers like Ridley, they state or imply that this was the scientific consensus at the time (snarky message: silly scientists can’t make your mind up). This is nonsense, but so popular amongst contrarians it is repeated frequently to this day.

If you want to know what scientists were really thinking and publishing in scientific papers read “The Myth of the 1970s Global Cooling Scientific Consensus”, by Thomas Peterson at al (2008), American Meteorological Society.

Warming, not cooling was the greater concern. It is astonishing that Ridley and others continue to repeat this myth. Has he really been unable – in the ten years since it was published – to read this oft cited article and so disabuse himself of the myth? Or does he deliberately repeat it because he thinks his readers are too lazy or too dumb to check the facts? How arrogant would that be?

2. He says: Valentina Zharkova of Northumbria University has suggested that a quiescent sun presages another Little Ice Age like that of 1300-1850. I’m not persuaded. Yet the argument that the world is slowly slipping back into a proper ice age after 10,000 years of balmy warmth is in essence true.

I say:

Oh dear, he cites the work of Zharkova, saying he is not persuaded, but then talks of ‘slowly slipping into a proper ice age’. A curious non sequitur. While we are on Zharkova, her work suffered from being poorly communicated.

And quantitatively, her work has no relevance to the current global warming we are observing. The solar minimum might create a -0.3C contribution over a limited period, but that would hardly put a dent in the +0.2C per decade rate of warming.

But, let’s return to the ice age cycle. What Ridley obdurately refuses to acknowledge is that the current warming is occurring due to less than 200 years of man-made changes to the Earth’s atmosphere, raising CO 2 to levels not seen for nearly 1 million years (equal to 10 ice age cycles), is raising the global mean surface temperature at an unprecedented rate.

Therefore, talking about the long slow descent over thousands of years into an ice age that ought to be happening (based on the prior cycles), is frankly bizarre, especially given that the man-made warming is now very likely to delay a future ice age. As the a paper by Ganopolski et al, Nature (2016) has estimated:

“Additionally, our analysis suggests that even in the absence of human perturbations no substantial build-up of ice sheets would occur within the next several thousand years and that the current interglacial would probably last for another 50,000 years. However, moderate anthropogenic cumulative CO 2 emissions of 1,000 to 1,500 gigatonnes of carbon will postpone the next glacial inception by at least 100,000 years.”

And why stop there, Matt? Our expanding sun will boil away the oceans in a billion years time, so why worry about Brexit; and don’t get me started on the heat death of the universe. It’s hopeless, so we might as well have a great hedonistic time and go to hell in a handcart! Ridiculous, yes, but no less so than Ridley conflating current man-made global warming with a far, far off ice age, that recedes with every year we fail to address man-made emissions of CO 2 .

3. He says: Well, not so fast. Inconveniently, the correlation implies causation the wrong way round: at the end of an interglacial, such as the Eemian period, over 100,000 years ago, carbon dioxide levels remain high for many thousands of years while temperature fell steadily. Eventually CO 2 followed temperature downward.

I say:

The ice ages have indeed been a focus of study since Louis Agassiz coined the term in 1837, and there have been many twists and turns in our understanding of them even up to the present day, but Ridley’s over-simplification shows his ignorance of the evolution of this understanding.

The Milankovitch Cycles are key triggers for entering, an ice age (and indeed, leaving it), but the changes in atmospheric concentrations of carbon dioxide drives the cooling (entering) and warming (leaving) of an ice age, something that was finally accepted by the science community following Hays et al’s 1976 seminal paper (Variations in the Earth’s orbit: Pacemake of the ice ages) , over 50 years since Milankovitch first did his work.

But the ice core data that Ridley refers to confirms that carbon dioxide is the driver, or ‘control knob’, as Professor Richard Alley explains it; and if you need a very readable and scientifically literate history of our understanding of the ice cores and what they are telling us, his book “The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future” is a peerless, and unputdownable introduction.

Professor Alley offers an analogy. Suppose you take out a small loan, but then after this interest is added, and keeps being added, so that after some years you owe a lot of money. Was it the small loan, or the interest rate that created the large debt? You might say both, but it is certainly ridiculous to say the the interest rate is unimportant because the small loan came first.

But despite its complexity, and despite the fact that the so-called ‘lag’ does not refute the dominant role of CO 2 , scientists are interested in explaining such details and have indeed studied the ‘lag’. In 2012, Shakun and others published a paper doing just that “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation”(Jeremy D. Shakun et al, Nature 484, 49–54, 5 April 2012). Since you may struggle to see a copy of this paywalled paper, a plain-English summary is available.

Those who read headlines and not contents – like the US Politician Joe Barton – might think this paper is challenging the dominant role of CO 2 , but the paper does not say that. This paper showed that some warming occurred prior to increased CO 2 , but this is explained as an interaction between Northern and Southern hemispheres, following the Milankovitch original ‘forcing’.

The role of the oceans is crucial in fully explaining the temperature record, and can add significant delays in reaching a new equilibrium. There are interactions between the oceans in Northern and Southern hemispheres that are implicated in some abrupt climate change events (e.g. “North Atlantic ocean circulation and abrupt climate change during the last glaciation”, L. G. Henry et al, Science, 29 July 2016 • Vol. 353 Issue 6298).

4. He says: Here is an essay by Willis Eschenbach discussing this issue. He comes to five conclusions as to why CO 2 cannot be the main driver

I say:

So Ridley quotes someone with little or no scientific credibility who has managed to publish in Energy & Environment. Its editor Dr Sonja Boehmer-Christiansen admitted that she was quite partisan in seeking to publish ‘sceptical’ articles (which actually means, contrarian articles), as discussed here.

Yet, Ridley extensively quotes this low grade material, but could have chosen from hundreds of credible experts in the field of climate science. If he’d prefer ‘the’ textbook that will take him through all the fundamentals that he seems to struggle to understand, he could try Raymond Pierrehumbert’s seminal textbook “Principles of Planetary Climate”. But no. He chooses Eschenbach, with a BA in Psychology.

Ridley used to put up the appearance of interest in a rational discourse, albeit flying in the face of the science. That mask has now fully and finally dropped, as he is now channeling crank science. This is risible.

5. He says: The Antarctic ice cores, going back 800,000 years, then revealed that there were some great summers when the Milankovich wobbles should have produced an interglacial warming, but did not. To explain these “missing interglacials”, a recent paper in Geoscience Frontiers by Ralph Ellis and Michael Palmer argues we need carbon dioxide back on the stage, not as a greenhouse gas but as plant food.

I say:

The paper is 19 pages long, which is unusual in today’s literature. The case made is intriguing but not convincing, but I leave it to the experts to properly critique it. It is taking a complex system, where for example, we know that large movements of heat in the ocean have played a key role in variability, and tries to infer (explaining interglacials) that dust is the primary driver, while discounting the role of CO 2 as a greenhouse gas.

The paper curiously does not cite the seminal paper by Hays et al (1976), yet cites a paper by Willis Eschenbach published in Energy & Environment (which I mentioned earlier). All this raised concerns in my mind about this paper.

Extraordinary claims require extraordinary evidence and scientific dialogue, and it is really too early to claim that this paper is something or nothing; even if that doesn’t mean waiting the 50 odd years that Milankovitch’s work had to endure, before it was widely accepted. Good science is slow, conservative, and rigorous, and the emergence of a consilience on the science of our climate has taken a very long time, as I explored in a previous essay.

Ralph Ellis on his website (which shows that his primary interest is the history of the life and times of Jesus) states:

“Ralph has made a detour into palaeoclimatology, resulting in a peer-review science paper on the causes of ice ages”, and after summarising the paper says,

“So the alarmists were right about CO 2 being a vital forcing agent in ice age modulation – just not in the way they thought”.

So was this paper an attempt to clarify what was happening during the ice ages, or a contrivance, to take a pot shot at carbon dioxide’s influence on our contemporary climate change?

The co-author, Michael Palmer, is a biochemist, with no obvious background in climate science and provided “a little help” on the paper according to his website.

But on a blog post comment he offers a rather dubious extrapolation from the paper:

“The irony is that, if we should succeed in keeping the CO 2 levels high through the next glacial maximum, we would remove the mechanism that would trigger the glacial termination, and we might end up (extreme scenario, of course) another Snowball Earth.”,

They both felt unembarrassed participating in comments on the denialist blog site WUWT. Quite the opposite, they gleefully exchanged messages with a growing band of breathless devotees.

But even if my concerns about the apparent bias and amateurism of this paper were allayed, the conclusion (which Ridley and Ellis clearly hold to) that the current increases in carbon dioxide is nothing to be concerned with, does not follow from this paper. It is a non sequitur.

If I discovered a strange behavour like, say, the Coriolis force way back when, the first conclusion would not be to throw out Newtonian mechanics.

The physics of CO 2 is clear. How the greenhouse effect works is clear, including for the conditions that apply on Earth, with all remaining objections resolved since no later than the 1960s.

We have a clear idea of the warming effect of increased CO 2 in the atmosphere including short term feedbacks, and we are getting an increasingly clear picture of how the Earth system as a whole will respond, including longer term feedbacks. There is much still to learn of course, but nothing that is likely to require jettisoning fundamental physics.

The recent excellent timeline published by Carbon Brief showing the history of the climate models, illustrates the long slow process of developing these models, based on all the relevant fundamental science.

This history has shown how different elements have been included in the models as the computing power has increased – general circulation, ocean circulation, clouds, aerosols, carbon cycle, black carbon.

I think it is really because Ridley still doesn’t understand how an increase from 0.03% to 0.04% over 150 years or so, in the atmospheric concentration of CO 2 , is something to be concerned about (or as I state it in talks, a 33% rise in the principal greenhouse gas; which avoids Ridley’s deliberately misleading formulation).

He denies that he denies the Greenhouse Effect, but every time he writes, he reveals that really, deep down, he still doesn’t get it. To be as generous as I can to him, he may suffer from a perpetual state of incredulity (a common condition I have written about before).

Conclusion

Matt Ridley in an interview he gave to Russ Roberts at EconTalk.org in 2015 he reveals his inability to grasp even the most basic science:

“So, why do they say that their estimate of climate sensitivity, which is the amount of warming from a doubling, is 3 degrees? Not 1 degree? And the answer is because the models have an amplifying factor in there. They are saying that that small amount of warming will trigger a furtherwarming, through the effect mainly of water vapor and clouds. In other words, if you warm up the earth by 1 degree, you will get more water vapor in the atmosphere, and that water vapor is itself a greenhouse gas and will cause you to treble the amount of warming you are getting. Now, that’s the bit that lukewarmers like me challenge. Because we say, ‘Look, the evidence would not seem the same, the increases in water vapor in the right parts of the atmosphere–you have to know which parts of the atmosphere you are looking at–to justify that. And nor are you seeing the changes in cloud cover that justify these positive-feedback assumptions. Some clouds amplify warming; some clouds do the opposite–they would actually dampen warming. And most of the evidence would seem to suggest, to date, that clouds are actually having a dampening effect on warming. So, you know, we are getting a little bit of warming as a result of carbon dioxide. The clouds are making sure that warming isn’t very fast. And they’re certainly not exaggerating or amplifying it. So there’s very, very weak science to support that assumption of a trebling.”

He seems to be saying that the water vapour is in the form of clouds – some high altitude, some low – have opposite effects (so far, so good), so the warming should be 1C – just the carbon dioxide component – from a doubling of CO 2 concentrations (so far, so bad). The clouds represent a condensed (but not yet precipitated) phase of water in the atmosphere, but he seems to have overlooked that water also comes in a gaseous phase (not clouds). Its is that gaseous phase that is providing the additional warming, bringing the overall warming to 3C.

The increase in water vapour concentrations is based on “a well-established physical law (the Clausius-Clapeyron relation) determines that the water-holding capacity of the atmosphere increases by about 7% for every 1°C rise in temperature” (IPCC AR4 FAQ 3.2)

T.C. Chamberlin writing in 1905 to Charles Abbott, explained this in a way that is very clear, explaining the feedback role of water vapour:

“Water vapour, confessedly the greatest thermal absorbent in the atmosphere, is dependent on temperature for its amount, and if another agent, as CO 2 not so dependent, raises the temperature of the surface, it calls into function a certain amount of water vapour, which further absorbs heat, raises the temperature and calls forth more [water] vapour …”

(Ref. “Historical Perspectives On Climate Change” by James Fleming, 1998)

It is now 113 years since Chamberlin wrote those words, but poor Ridley is still struggling to understand basic physics, so instead regales us with dubious science intended to distract and confuse.

When will Matt Ridley stop feeling the need to share his perpetual incredulity and obdurate ignorance with the world?

© Richard W. Erskine, 2018