More Caterpillars: The Leaky Atmosphere Hypothesis – is global pressure a proxy for global temperature?

Most of this article was written before Roger Tallbloke pointed out that the suggestion the earth’s global temperature is controlled by the earth’s pressure was suggested by Nikolov & Zeller before 2011 (but on longer timescales). This means key point is toward the end where I suggest the caterpillar theory and pressure variations can be combined into a unified explanation of the ice  age cycle. However, whilst the hypothesis linking global temperature and pressure is less important here, the fact it was independently suggested makes it more the more worth considering.

Thanks Josh

Thanks Josh


Graph of CO2 levels and temperature of the earth over the last 600million years showing that temperature has varied significantly (and not correlated with CO2)

Until recently there was the concept of a “normal” temperature for the earth. Indeed, the whole global warming & cooling cooling scares stem from the view that the earth had departed from this “normal” temperature. However, the climate record just does not support this idea. Whether we look from day to day from year to year from century to century, millennium to millennium or one ice-age cycle to another, we see that the world naturally changes its temperature.
But just as temperature was once thought to be “normal”, the earth’s climate has one other massive megasaurus in the dunny. That is global pressure. I have looked online and as far as I can tell, there is not one single metric of “global average pressure” and certainly no “trend in global average pressure”.
That is quite unbelievable. Indeed, where I did find large-scale metrics of regional pressure, it seemed that global pressure was stated as a constant.
However any real scientists knows the basic equation:


where the letters denote pressure, volume, amount, the ideal gas constant, and temperature of the gas, respectively.

Or rearranging:

P ∝ NT

This would need to be modified for an open atmosphere which is not a closed container, but the general relationship that temperature rises with increasing atmospheric pressure and that pressure increases with increasing quantity of gas will apply.

The leaky Atmosphere Hypothesis

I am going to propose a hypothesis and it is this:

That the earth’s global temperature is a proxy for the earth’s global pressure. That global temperature varies over time as global pressure changes and that in turn global pressure changes because the amount of gas changes over time. And that this is because we have a leaky atmosphere which tends to lose gases and it is only sustained at its present level by constant additions through volcanic processes.

In it’s own way this hypothesis is as radical as suggesting that the Sun and not the earth is at the centre of the solar system. Or that the global temperature changes naturally over time (something still denied by alarmists – despite the evidence in clear sight that it does).

Model of carboniferous dragon fly showing how much larger flying insects were (all insects were larger) Source:

Model of carboniferous dragon fly showing how much larger flying insects were (all insects were larger)
Source: Scienceray

I was always taught that there is a standard atmospheric pressure. I was always led to believe that the atmosphere is constant and so like most other people I kind of assumed that the same amount of gas was always present. So, when e.g. people talk about the enormous insects from the Carboniferous as shown above, they always suggest higher oxygen levels, but I’ve yet to see any mention of pressure.
But what if oxygen levels went up because we had some kind of massive increase in volcanic activity which released huge amounts of CO2 which the plants kindly turned to O2? And that pressure went up, not because of rising CO2, but because the huge increase in the amount of atmospheric gas (i.e. more molecules), led to a rise in pressure and subsequent rise in temperature.

Overall Comment

If you think I have a paucity of evidence to back this suggestion – I agree with you. But reading books on the atmosphere, I got that very uneasy feeling that the earth was not quite the air tight container we are led to believe. Come on! Think about it! For the conventional theory to work – the earth has to be a completely utterly air tight container that has lost no gases for nearly a billion years.
In contrast, we know hydrogen is regularly lost from the atmosphere. And so given the nature of gases, it is just a statistical quirk that all other gases will be lost, but that the chances become increasingly small given their heavier weight. But they will be lost, that is for sure. And so I will say with utmost certainty that the earth is losing all gaseous constituents and unless these are replenished, will eventually lose its atmosphere entirely. What I don’t know is whether that time-scale matters.

The Ice-age cycle

Thanks Josh

I’ve been mulling this hypothesis since I investigated the ice-age cycle and decided that a very strong candidate for the regular change was what I called the “Caterpillar theory” of plate tectonics.
In this theory, I suggested initial changes in solar insolation induced global warming which in turn led to thermal expansion of the crust. That expansion then push the plates together causing subduction of one plate under another. This then led to thermal decomposition of the plate material and the subsequent evolution of large volumes of gas such as CO2, water vapour, and other things.

“average” ice-age cycle Haseler gap is dramatic drop in temperature (red) with no similar drop in Co2 (blue)

Initially, I thought I could combine some form of CO2 heating with the caterpillar theory to obtain a full explanation of the evolution of the ice-age cycle. But rather than CO2 acting directly on the atmosphere I proposed a more indirect root. Because CO2 is an essential plant food, and modern plants have sucked the atmosphere dry so we effectively live in a CO2 “desert”, small changes in CO2 could have a massive change on climate through the dramatic increase or decrease in plant growth. And as you probably know, plants respire creating much of the atmospheric water vapour and water vapour is a potent greenhouse gas – until it condenses as sun-shading clouds – effectively halting warming. So, plants directly affect climate. And there’s research showing that much of what we call “urban heating” is related to what grows in an area with cities being hottest because they have least plants and forest’s being coolest because they have most perspiration.
But this idea that CO2 controlled the climate through plants, ran aground when I found was something I jokingly referred to as the “Haseler gap” which was a period of dramatic drop in temperature after the inter-glacial peak with almost no change in CO2 (gap -as in between the ears – because I couldn’t understand it!). This was conclusive proof that temperature change was not primarily driven by  CO2. (And to be honest, I’m still strugling to explain it – although it seems to be correlated to a drop in insolation).
The Caterpillar theory is just the application of basic physics. The crust does expand that is physics. There will be thermal decomposition – that is chemistry. And given the length of ice-age cycles, there will be significant expansion and contraction over these time periods. The Caterpillar theory is true, what is less certain is whether the heating in the top few kms of the earth’s crust over the ice-age cycle is a minor effect or whether by some mechanism it can explain large scale effects.
However (as we are constantly being told by “skydragons”) there is a relationship between the amount of atmosphere and the temperature of the surface**, so that an increase in gas emissions will increase atmospheric pressure and raise temperature. As I said above, I’ve been unable to find any supporting evidence for a change in atmospheric pressure (although larger insects in carboniferous might be due to this). So, I can in no way prove the next hypothesis or even find any supporting evidence. But as good a way as any to ask for the help I need to find evidence to support or reject this hypothesis is to state it.
And it is this:

That the ice-age cycle is caused by a change in atmospheric pressure as a result of a dramatic injection of gases during the warming period and a slow leaking of the atmosphere as we head down into an ice-age.

 (What to call it? The Leaky-caterpillar theory?)

Addendum – it’s been proposed before

I’m adding this section in here because it now appears I’ve independently suggested something that has been briefly mentioned by Nikolov & Zeller:

A proposed key new driver of climate is the variation of total atmospheric mass and surface pressure over geological time scales, i.e.  tens of  thousands to hundreds of millions of years. According to our new theory, the climate change over the past 100-300 years is due to variations in global cloud albedo that are not related to ATE/GHE” (link, P.13)

And the paper (although not the proposed fluctuations in earth’s pressure) were on Roger’s blog in 2011 (Unified Theory of Climate, Nikolov and Zeller).

Brief overview of Adiabatic warming & “greenhouse warming”.

I was avoiding detailed discussion of adiabatic heating as it just ends in silly arguments from some who think it “disproves” CO2 warming. In fact, the two ways of describing the greenhouse effect (adiabatic and greenhouse gas) are both just simplifications and the difference stems only from what one chooses to simplify and are irrelevant in a real atmosphere.
A description of the “adiabatic warming” explanation of the atmosphere is in my article a simplified Atmospheric model” but the key points can be got from the diagram below.

Simplified atmospheric model: transparent to visible, opaque to IR

Simplified atmospheric model: transparent to visible, opaque to IR

In this simplified model, the atmosphere is considered to be opaque to all infra-red so that it emits only from the “top” of this opaque atmosphere. Because this top is in thermal equilibrium with space, in this model this is the “blackbody” surface seen by space. But this surface is cut off from the surface by the opaque atmosphere. And because temperature rises with pressure, the temperature at the surface of the earth is higher than the “top” of the atmosphere because of adiabatic heating.
Although a gross simplification, this is in practice not too bad an approximation to our atmosphere because around the top of the troposphere, there is almost nothing above and below is quite opaque to much IR. And because you can get a very close match to the real atmosphere by chose a suitable “top” and many a heated argument has resulted by assuming this good fit means it must be “true” and so disproves CO2 warming.
However although adiabatic cooling is important in a real atmosphere, a real atmosphere doesn’t just radiate from the “top”. Instead gases like CO2 mean that IR is irradiated from a range of layers (even if most are above the bulk of the atmosphere). And what increasing CO2 does is to in effect move the effective “top” of the atmosphere higher up so that there is more adiabatic warming. I agree this isn’t what you read on alarmist blogs which only work by ignoring the radiation from CO2 and only considering the radiation absorbed by CO2. That “noddy” theory correctly predicts warming, but it is so simplified that it has rightly caused many people to doubt its validity.
So, although both the “greenhouse gas” and adiabatic warming are both gross simplifications but if you understand that they are gross simplifications and understand their limitations, they are both consistent with the real atmosphere (when applied with common sense).

Other Addendum

Roger Tallbloke, sent me an email and made the interesting point that: “An increase in solar activity will heat the Earth more by radiation, but also cool the Earth by stripping away more of its atmosphere with faster/denser solar wind, reducing atmospheric pressure. It takes longer to warm through rebuilt pressure from outgassing than to cool from reduced radiation, all clouds being equal.” That’s a very valid point raising the possible connection between solar activity and earth’s global pressure and one I had not considered.

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18 Responses to More Caterpillars: The Leaky Atmosphere Hypothesis – is global pressure a proxy for global temperature?

  1. Pingback: Josh Cartoon: I see no Caterpillar | Scottish Sceptic

  2. Scottish-Sceptic says:

    Roger Tallbloke, who’s completely wrecked my original article with all his helpful suggestions 🙂 commented:
    the evidence is the pterosaur skeletons. I don’t think those creatures evolved in order to go for a long ungainly climb every time they wanted to glide somewhere. For true flight, the air must have been significantly denser.

  3. tallbloke says:

    Mike, thanks for mentioning Nikolov & Zeller. The original article on the talkshop is here
    The best evidence for a denser atmosphere when it was a lot warmer millions of years ago is the physiology of flying reptiles. They could only have supported their weight in true flight in a denser atmosphere.

  4. The atmospheric surface pressure is also affected by the amount of water suspended in the atmosphere in four phases colloid snow flakes (mostly in the tropopause), gas (in the lower troposphere), airborne water condensate, an aerosol colloid (all clouds seen and unseen), and precipitation (acceleration limited by air viscosity. This also actually changes the surface pressure with latitude. Your id-ing the flaky concept of constant pressure is nice. Thank you!

    • Scottish-Sceptic says:

      Another good point – indeed, if we go from the dry conditions in the ice-age to the present moist conditions, there must be a considerable increase in weight and therefore pressure and therefore temperature.
      It’s about time I worked out some actual figurs:-
      Using Niklov and Zeller’s ( approximation we have:
      Ts/Tgb = exp(.233Ps^0.0651 + 0.00154Ps^.385)
      At earth’s pressure (101325 Pa) & Tgb of of =154.3,
      A 10% increase in pressure suggests a 2.3C rise in temperature – or looking at the total curve:-
      -50% -14.5C
      -40% -11.0C
      -30% -7.9C
      -20% -5.0C
      -10% -2.4C
      0% 0.0C
      10% 2.3C
      20% 4.4C
      30% 6.4C
      40% 8.4C
      50% 10.2C
      Thus suggesting that in the ice ages, the 8C drop in temperature could be explained by a 30% drop in pressure. Total water vapour is of the order of 0.5%. So at worst, going from 0% to 100% humidity is only going to equate to around a 0.1C change in global temperature. (It also means that a 5,000ppm change in weight of atmosphere equates to 0.1C – so the 100ppm change in CO2 isn’t even worth calculating!)

  5. Kristian says:

    Greetings from Norway, Scottish Sceptic. I like your thoughts. To me it’s pretty obvious that it is an atmosphere’s total mass and not its species-specific IR activity (absorptivity) that elevates a solar-heated planetary surface above a hypothetical pure solar radiative equilibrium.
    I’ve just written a couple of blog posts that should tie in nicely with the fundamental message of this one:
    This figure (from Part 2) should explain the basic mechanism:

    • Scottish-Sceptic says:

      I was going to say “I think people who work in this field will already understand it” … but then I realised that I had never ever seen anything from anyone to suggest they understand it the same way as me … and given how much crap we get from academia on climate, I can but hope that some people do understand the way I do.
      Basically, I don’t believe there is a failing of knowledge (at least not yet), instead I think that academia pushes a particular simplified version for political reasons as it highlights the problem of CO2.
      But we are talking about some of the most useless people around and a generally extremely poor standard of “science” so perhaps nothing would surprise me any longer.
      Using the greenhouse analogy – in the same way the vast bulk of insulation comes from simply stopping the hot air moving away, so the vast bulk of the “greenhouse” effect comes from adiabatic warming. But CO2 is a bit like having slightly thicker glass. It doesn’t account for most of the greenbouse warming – and it doesn’t even behave like most of the greenhouse – but it does contribute to higher temperatures. But not so much by radiative absorption, but because increasing levels effectively move the top of the astmosphere higher by a small fraction. So, in effect, the “top” of the CO2 column is now at a higher level, that higher level is colder, and that means less IR is being emitted.
      – and notice I’ve not mentioned trapping at all. Instead, I’ve assumed that CO2 traps all radiation until it gets to the “top” … and that what is important is the average height of this “top”.

      • Brett Keane says:

        Last I saw, the average cloud level had lowered enough to eliminate any possible CO2 effect. But, in any case, CO2 rising higher would be radiating at the ‘warmer’ rate, just more spread out. But with the same number of molecules in the greater space available. The ghg hypothesis has failed all tests, and this higher emission level thing is just flogging a dead horse. Hot spot? More water vapour? etc. Wherefore art thou?
        Paltridge, G., Arking, A. and Pook, M. 2009. Trends in middle- and upper-level tropospheric humidity from NCEP reanalysis data. Theoretical and Applied Climatology: 10.1007/s00704-009-0117-x.

        • Scottish-Sceptic says:

          Imagine a plantation of red and blue trees – the blue trees closer to you.
          If the trees are very sparsely planted so you can easily see through to the trees, although some red tress will be obscured, many will be visible and the average colour will tend toward an average of red and blue as the trees are more and more sparse.
          In contrast, if the trees are very dense, you only see the ones at the front and so the wood appears blue.
          The noddy explanation of the change in colour from red-blue to blue (equivalent to alarmists on CO2) is because you can no longer see the view BEHIND the wood. So, they are trying to say that the less background (I assume it is green), the more the colour changes. But this is clearly nonsense, because what if the background were bright blue and the front trees were reddy-blue. Then the more trees, the less blue you see.
          Instead, the explanation is which part of the wood can be seen from outside.
          And this is all that matters – at the wavelength being measured, what is the temperature of the part of the atmosphere or surface from which that radiation comes.
          The temperature is set by adiabatic temperature drop. And in a dense atmosphere the surface temperature does not matter at all, because we cannot see through the “wood”. Instead it is how dense the trees are close to us which determines whether we see the bluest trees closest to us or some redder trees further in.
          Of course – what I am omitting is the fact that when large heat flows stem from certain layers, this in itself changes the atmosphere and changes the temperature gradient. But at that point the modelling become crazily complex.

    • Scottish-Sceptic says:

      I was reading your articles and this diagram looks a good way to explain it:
      You’ve got a good drawing of the atmosphere getting thinner and shown how the effective height increases.
      But now let us consider the CO2 molecules and assume that CO2 sits in a radiative “window” only emitting and absorbing its own radiation (except at the ground).
      As the density of CO2 in the atmosphere increases, the effective height from which radiation in the CO2 emits raises and lowers as per your diagram. This is why CO2 causes warming. Because it is the only gas in this “window” and because the other inert gases cause the adiabatic lapse, a small change in CO2 causes the effective average height to raise and lower significantly for a relatively small change in CO2 (within this window).

      • Kristian says:

        So why don’t we see this happening on Mars? Its atmospheric CO2 (28 times thicker on the ground than on Earth) very clearly intercepts part of the window radiation:
        Yet, the Martian ERL and surface temperatures are one and the same.
        Absorbing IR from the ground and emitting it to space from higher up clearly does not automatically translate into surface warming.

        • Scottish-Sceptic says:

          If they are the same, then most reasonable people would know that they are the same because someone started with the result and worked back.
          If you had said “they are very similar”, then that’s more realistic and not unreasonable given that we are dealing with approximations from planets where there is no one to do actual measurements.
          What we do know is that the atmospheres will behave according to the laws of physics. What we don’t so well is which laws and how to apply them.
          But we do know that a model where CO2 only absorbs and has no emissions is just cloud cuckooland non-science.
          And there are two limiting cases. One is where CO2 is so dense, that the radiation hardly gets anywhere through the atmosphere without interacting. In this case, adding more of the gas might change the mean path from say 10m to 9m, but 1m in at atmosphere 10s of km thick is not going to make any difference. The other is where the atmosphere is almost transparent, and in this situation, the emissions can more or less be assumed to be coming evenly from all levels. And again, adding more gas will not significantly change the average height from which it is emitted.
          In between these two extremes we have a real atmosphere which tends to absorb some radiation from the surface and so as seen from space, the emissions tend to come from the upper most “parts”. Now, as more gas is added, it tends to mask IR from lower levels so that the average height from which radiation escapes the planet tends to rise with more gas concentration. And because the temperature reduces with height (at least where there’s substantial amounts of gas), the amount of radiation decreases as more gas is added.
          But as to putting numbers on that which is what I would need to answer your question – I would need to do a lot of work and have access to loads of information and basically get paid for doing that job.

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