Following Arrhenius on global warming

But he did change his mind …

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This 1912 newspaper article (right) shows that a century ago the worthy citizens of Warkworth were followers of Svante Arrhenius’s new theory that global warming would be caused by mankind’s emissions of greenhouse gases.

Forty years earlier Tyndall had identified CO2 as a greenhouse gas. Arrhenius followed up with newly available data in 1896 and calculated that doubling CO2 would increase temperatures by 5°C or 6°C. In 1906 he reduced it to 4.0°C.

Arrhenius is frequently cited by warmsters chiding sceptics for their lack of belief, telling them, “Science has known about dangerous warming for 120 years.” But science knew nothing of dangerous warming, because Arrhenius showed none. He was free of the modern pathological aversion to carbon dioxide (the gas of life) because he saw no reason to object to it.

Benefits from CO2 indisputable

Tyndall and Arrhenius were drawn to investigating ice ages and thought CO2 could trigger them, while man-made emissions might also prevent them. He knew that CO2 was necessary for plant growth as well, so he had no concerns about the gas and thought whatever warming ensued would be beneficial.

Much scientific discussion took place after 1896 and some rejected any effect of CO2. Arrhenius published a paper in German amending his view of increased CO2 on climate, lowering his estimates by several degrees and saying any warming would be beneficial. It was not translated at the time though it was widely known by European scientists.

Since Arrhenius’s paper in 1896, man-made emissions of carbon dioxide have increased 18-fold, from 2 billion tons a year to 36 billion tons, yet global temperatures have barely moved — about 0.8°C, much of it from natural variability. Successive IPCC Assessment Reports have moved the warming steadily downwards as earlier forecasts proved too hot.

Planning an electricity substation near the coast or a stormwater outfall on the beach must be a nightmare for engineers. They have to redraw their plans every few years to accommodate the changing predictions of sea level. Meanwhile, the rate of sea level rise has remained unchanged for a hundred years. Anyway, here is the predicted 2100 warming from the Executive Summaries in the five assessment reports.


The first assessment report (FAR) used the term “prediction” to describe the model outputs, but that was the first and last time. Scientists complained about the use of unverified computer models being treated as data. Extrapolation from observations might correctly be called predictions, but unvalidated model output, which may be well informed, is yet no better than a guess. Strong criticism by an expert reviewer, the late New Zealand scientist Vincent Gray, restrained the IPCC’s use of the term “prediction” rather than the proper term “projection” — as, he told us, they had agreed.

All five Assessment Reports

FAR – 1990

Under the business-as-usual scenario (Scenario A), the IPCC predicted warming of 3°C before 2100.

SAR – 1995

Under the mid-range scenario (IS92a) the IPCC projected warming of about 2°C by 2100.

TAR – 2001 (the Hockey Stick on page 3!)

IPCC said warming would be up to 5.8°C by 2100. Big jump, this.

AR4 – 2007 (no Hockey Stick, not seen again)

The IPCC’s “best estimate” of warming was up to 4.0°C by 2100.

AR5 – 2013

The IPCC forecasts up to 4.8°C from the ludicrous RCP8.5 scenario because it assumes we burn all the coal the earth contains, which is preposterous. Besides that, they expect warming of up to 3.1°C by 2100. – Table TS.1 p. 90

Lingering ambiguities

In the translation of Arrhenius’s 1906 Amended View of The Probable Cause of Climate Fluctuations are several mutually contradictory statements of warming. I couldn’t fully discriminate between them, so perhaps you can help. Page 6 says:

I calculate that a reduction in the amount of CO2 by half, or a gain to twice the amount, would cause a temperature change of – 1.5 degrees C, or + 1.6 degrees C, respectively.

Further, pages 7 & 8 have these contradictory statements.

one finds that with a change in the quantity of CO2 in the ratio of 1:2, the temperature of the Earth’s surface would be altered by 2.1 degrees.

the total temperature change induced by a decrease in CO2 in the air by 50% is 3.9 degrees (rounded to 4 degrees C).

The topic is fascinating and shows that after a hundred years we pesky sceptics are still unconvinced. If only they’d throw us some evidence, we could go away!


14 Thoughts on “Following Arrhenius on global warming

  1. Barry Brill on May 24, 2020 at 8:50 pm said:

    I’m depressed by the fact that New Zealand media have been running alarmist articles about DAGW (dangerous anthropogenic global warming) for at least 108 years, but in all that period they have never ever taken the obvious next step of asking ‘how much’?

    Even avid news junkies know nothing about “climate sensitivity”. They hear the same shallow slogans repeated on an almost daily basis, and over 90% of readers have sensibly switched off. Thousands of column inches go unread – because you know they will say nothing you haven’t heard a thousand times before.

    While there are many shades of opinion about temperature predictions/projections, most climate sceptics believe that humankind might have SOME impact on the 2100 global average surface temperature (GAST) – but they think it will be trivial. Climate campaigners claim it will be huge. The majority seem to think it might be significant. Here’s the real debate: how much?

    If the media had reported on the real debate over the past century or so, news junkies would now be very familiar with terms like ‘equilibrium climate sensitivity'(ECS) and ‘transient climate response’ (TCR). And they would follow the arguments and read the opinion pieces. We would all be interested in the answers to the questions Arrhenius posed in 1906.

    In my view, old Svante got it pretty right on page 6 of his landmark publication, that an eventual doubling of CO2 might well cause a temperature change of 1.5 – 1.6°C. Almost all the evidence-related research appearing in the last 10 years has agreed that the ECS is around this level.

    On the basis of this historic learning, we won’t experience 1.5°C of additional warming unless/until the atmospheric concentration of CO2 INCREASES by a huge 400ppm. Nobody expects that to happen in the next 100 years!

  2. Simon on May 25, 2020 at 9:53 am said:

    Arrhenius’s statements are not mututally (sic) contradictory, he’s showing intermediate steps in the calculation:

    In a similar way, I calculate that a reduction in the amount of CO2 by half, or a gain to twice the amount, would cause a temperature change of – 1.5 degrees C, or + 1.6 degrees C, respectively. In these calculations, I completely neglected the presence of water vapour emitted into the atmosphere.
    The average water vapour content of the whole atmosphere corresponds to approximately an absorbent layer 4 cm in length. Thus the water vapour would reduce the Earth’s radiation by 1/3 x 61.6 = 20.5%. If one uses this correction, one finds that with a change in the quantity of CO2 in the ratio of 1:2, the temperature of the Earth’s surface would be altered by 2.1 degrees.
    The water vapour in the atmosphere does not only keep back the Earth’s radiation, but also absorbs a large part of the solar radiation. This last circumstance works in opposite directions, but not nearly as vigorously as the former. For this related correction, I have used the data of Ångström and Schukewitsch. * The calculations show that a doubling of the quantity of water vapour in the atmosphere would correspond to raising the temperature by an average of 4.2 degrees C.
    For this disclosure, one could calculate that the corresponding secondary temperature change, on a 50% fluctuation of CO2 in the air, is approximately 1.8 degrees C, such that the total temperature change induced by a decrease in CO2 in the air by 50% is 3.9 degrees (rounded to 4 degrees C).

    • Richard Treadgold on May 25, 2020 at 10:45 am said:


      As I said, these statements are mutually contradictory. What would you say was Arrhenius’s conclusion? Would it be ±1.5/1.6°C, ±2.1°C, or ±4°C? That is the point.

    • Rick on May 28, 2020 at 3:17 am said:


      Congratulations on your success in having sifted out some definite statements about climate sensitivity from the overgrowth of ponderous verbiage in which they are embedded which, I must confess, has stymied all my attempts over the years to follow Arrhenius’s train of thought from the beginning to the end of his 1896 paper.

      You say these statements are mutually contradictory and, on the face of it, they certainly appear to be so. Simon seems to think that their mutual contradiction disappears when you take their contexts into account, but he hasn’t explained their contexts in terms that I, at least, can understand. He has merely repeated some of Arrhenius’s own verbiage that surrounds them which, as I’ve just explained, is mostly impenetrable to me. So those statements still appear mutually contradictory to me, as their immediate out-of-context appearance is all I have to judge them by.

      I have managed to grasp, though, that Arrhenius’s general conclusion about the climate sensitivity to CO2 was that it is “logarithmic” in nature. To be more precise, his analysis led him to the conclusion that proportional increases in atmospheric CO2 concentration (and water vapour concentration separately) would produce approximately equal increments of temperature at the planet’s surface.

      Arrhenius did stipulate though that this conclusion could only apply to the range of the data on which his analysis was based. And in his day at least, there were no available data regarding the global mean surface temperature, which simply was not measurable in 1896 (and still isn’t today, in fact, although that is another matter, of course). So he could not draw any logical inferences about the effects of CO2 and water vapour on the global mean surface temperature from the actual data which were available to him. Therefore, his conclusion had to be merely a tentative, hypothetical proposition which could form the subject of future scientific testing and it was not the immutable certainty which modern-day IPCC ‘climate scientists’ appear to have taken it to be.

    • Richard Treadgold on May 28, 2020 at 12:01 pm said:

      Well, yes, a small victory, to be sure, but I’ll take it and thanks. In attempting to use Arrhenius’s work to support their fabricated view of mankind’s emissions, modern warmsters distort it. They especially ignore his later corrections — perhaps hardly surprising, considering they ignore thousands of more significant modern papers questioning their analyses and conclusions in almost every facet of climate.

      As Barry says, it’s reasonable not to expect atmospheric CO2 to reach 800 ppmv this century. IPCC’s AR5 estimate of CO2 concentration by 2100 is difficult to find. After chasing through the AR5 for about an hour and a half I must put it aside. I’ll try later to find it in the Technical Summary (86 pp). Strangely, Chapter 11, Near-term Climate Change: Projections and Predictability, goes coy on discussing anything other than CH4 and O3, while Chapter 12, Long-term Climate Change: Projections, Commitments and Irreversibility, seemingly the obvious option for future concentrations, fixes its attention on temperature and emissions, without mentioning parts per million of anything.

      But well put, and I agree with you.

  3. Rick on May 25, 2020 at 11:57 am said:

    Climate alarmists hail Arrhenius as one of the founding fathers of their ‘science’, because, so they say, his 1896 paper established scientifically that there is a fixed, logarithmic relationship between atmospheric CO₂ and the global mean surface temperature. The IPCC’s well-known logarithmic formula for the amount of ‘radiative forcing’ that is directly produced by a given increase of atmospheric CO₂ enshrines this relationship (called the ‘Arrhenius law’). That logarithmic formula is the central, core foundation of alarmist global warming theory and without it the entire edifice would collapse. So, Arrhenius is a crucially important character in the alarmist narrative of dangerous, or catastrophic man-made global warming and without his ground-breaking 1896 paper, there could be no ‘science’ of man-made global warming today.

    But any genuine, honest climate scientist would have to admit that the Arrhenius law has never been verified empirically and therefore its true status in science is that of an unproven theoretical conjecture, not a demonstrated and confirmed scientific fact. In my view, to characterise something as a scientific law of nature when it is really only a speculative mathematical possibility without empirical support is to imbue it with an aura of absolute scientific authority that it does not really possess. This is a very flimsy basis on which to build a ‘science’ and very thin ice for pretentious ‘scientists’ to skate on. However, fools rush in… of course.

    • Mack on May 25, 2020 at 1:17 pm said:

      Exactly, Rick, …. in addition, Arrhenius was a member of the Swedish Society for Racial Hygiene….which has got nothing to do with washing hands and brushing teeth.

    • Rick on May 26, 2020 at 11:03 am said:

      I didn’t know that, Mack. Arrhenius was undoubtedly a bright spark, but he also had a certain tendency to make sweeping unqualified assumptions about things, I’ve always felt, and so I’m not surprised to learn from you that he was involved in the eugenics movement in Sweden.

  4. Mack on May 25, 2020 at 2:40 pm said:

    Looking at that 1912 newspaper clipping … the worthy citizens of Warkworth were probably not aware of Arrhenius and his new theory….. but were certainly made aware of enormous (9 zeros) amounts of CO2 emitted into the atmosphere by humans…. a great anxiety inducing, scientific news story.
    The amounts might be undisputed …. but then the journalist goes further… lapsing into his own pseudo-scientific “knowledge” …. “This tends to make the air a more effective blanket for the earth and to raise its temperature”
    There you have it… the old “blanket” analogy. …. and then of course… the blanket is keeping you warm….. Just like James Renwick and his duvets. The atmosphere acts as a duvet keeping us warmer….than…. an Earth with NO ATMOSPHERE. That is what the newspaper journalist implied….thicker (more effective) blanket will “raise it’s temperature”
    So a blanket, we all know, acts as an insulator….but it doesn’t take genius to figure that an insulator is a double-edged sword and works from both sides. The wacko “greenhouse” theory tries to tell us that the the atmosphere is somehow “transparent” to infra red wavelengths of the Sun’s radiation. …no, everything is heated up by the Sun…atmosphere included.
    The source of heat is THE SUN which is OUTSIDE the “blanket”. An analogy for this insulation would be a hot-water cylinder with insulation to keep water hot. In hot parts of the world, they use hot-water cylinders to keep water cool.
    We’re surrounded by intellectual loons.

    • Brett Keane on May 26, 2020 at 6:22 am said:

      Mack, Excellent summation!
      In the 1860s, Maxwell showed how the Ideal Gas Laws and Gas Kinetics obviated all blanketting except that provided by the Mass of all Gases. So Venus follows our Adiabat, adjusted for Solar distance and Mass, but zero CO2 effect. Likewise all of the many measured Planets and Moons.
      Only at Critical Pressures/Temperatures or below one tenth of a Bar do the Gravito-Thermal Effects cease. Because Physically, we ae then not dealing with an ‘Atmosphere of gases’. Plasma or Cosmic Physics then take over…….. Brett Keane

    • Mack on July 3, 2020 at 12:42 am said:

      I was just reading my comment here and began to consider how much the Greenhouse hypothesis has inbuilt, deceptive illusions leading to the delusion of a “warming” effect of the atmosphere. The biggest deception of nature is the concept of space being cold. Space craft have to revolve out in space, say, between here and the moon or Mars, because otherwise they would get red hot on the side facing the Sun and freeze on the other side. So the concept that it gets hotter further up in the TOTAL atmosphere is quite hard to grasp. Here’s the Earth’s atmosphere temperature profile…'s%20Atmosphere/Layers%20of%20the%20Earth's%20Atmosphere%20Worksheet%20includes%20background%20info,%20student%20worksheet,%20answer%20key.pdf
      (just the blue graph with the red line)
      Everybody is fooled by the troposphere being colder the further up you go. …they just need to climb a mountain to know that. Arrhenius, Fourier, Tyndall, etc. way back in those days, can be forgiven for not having the knowledge about Earth’s atmospheric temperature profile…. knowledge about the thermosphere….let alone the temperatures of air molecules in the themosphere. Those fine gentlemen would have not much further insight to Earth’s atmosphere than just above the clouds…… hence the conjectural formulation of the “Greenhouse” theory.
      Which brings me to the fact we have people like this arrogant academic, head of “climate science” at Oxford University…. Myles Allen. …. who’s head has moved no further than cloud-cuckoo land above the clouds. Oxford University with its Oxford Dictionary, defining the word “denier” as a person who doesn’t believe in “climate change”.
      Dr Allen has lectured us all on the science right here at REAL CLIMATE… he’s lectured us all on his scientific proof that AGW exists…. and what’s more, this lecture has been presented as evidence to Judge Alsup of the American courts. !!! A climate clown like Myles Allen should not be forgiven for such lazy and ignorant thought processes in this century. He’s seen my comment, because he commented directly above it . But it seems he would just prefer to talk to a rabbit.

  5. Brett Keane on May 26, 2020 at 5:56 am said:

    RT: Good Post! Of Course, Prof Robert Wood(s), the great Photonic Physicist, did the experiments that disproved Arrhenius’ musings . Check em out.
    Svante was a decent Scientist. He saw Wood was right, and moved on to other fields of research.
    How the pigmies have usurped the Field of Giants……… Brett Keane


  6. Brett Keane on May 26, 2020 at 8:57 am said:
    Getting Circular here, but the site has been so educational to me for years. And has defeated the warmist criminals at their own game by scientific acumen and research.

    I do hope WordPress can clean up their leeching hackers soon so I can use it again…….
    Brett Keane

    It’s great that oldbrew, whoever he is, picked this up for Tallbloke’s Talkshop. There are many substantial comments over there, too.

    • Brett Keane on May 26, 2020 at 11:08 pm said:
      Also great to once again dip into Casey’s excellent work. Trolls, on the other hand, never got over their adolescent dope damage, so they still imagine energy can be multiplied witout effort. That is, Magic.
      It is always sad to see Maxwell and Woods etc. ignored again for Svante’s musings. We carry the dead weight of these charlatans, who will have to make account one day. At least they do provide free comedic entertainment, riding their Perpetuum Mobiles…….

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