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.
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:
PV = NRT
where the letters denote pressure, volume, amount, the ideal gas constant, and temperature of the gas, respectively.
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).
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.
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
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.
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.
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).
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.