The Greenhouse Effect - a Fork in the Road
Why are the inner workings of the Greenhouse Effect so seldom discussed?
Could it be that the climate models are based on an assumption which contradicts well established laws of thermodynamics?
We are often told that the Greenhouse Effect has been ‘well understood for more than a century’.
In other words, ‘stop asking questions, this stuff is obvious!’
But despite Gary Lineker’s (yes, the ex-England footballer!) claims, I consider the theory that underpins all of the catastrophic weather-related claims to be far from ‘indisputable’.
Quick recap - ‘The Atmospheric Turbo Effect’
My previous article called What is the Greenhouse Effect? describes how the presence of carbon dioxide (CO2) and other greenhouse gases (GHGs) are said to absorb long-wave infrared radiation (LWIR) that would otherwise be lost to space.
The retention of this radiation, according to the Greenhouse Effect theory, results in a rise in thermometer readings housed within meteorological stations around the world.
Another way to think of this concept is like a turbo on a sports car. The turbo harnesses energy in the car’s exhaust gases to drive a turbine, which in turn pushes more air through the combustion chamber thereby improving performance.
The turbo doesn’t create any additional energy, but rather re-utilizes energy that would otherwise be lost through the exhaust. Similarly;
Greenhouse gases don’t add any additional energy into the system, they reapply energy that would otherwise be lost to space.
‘The fork in the road’
My previous article is well worth reading to elevate your understanding above the standard ‘CO2 traps heat’ explanation of the Greenhouse Theory.
But it didn’t attempt to answer the following, central question:
How *exactly* do greenhouse gases turn the absorption of long-wave infrared radiation into higher atmospheric temperatures?
This question is seldom discussed. We are often left with the simple impression that radiation = energy = heat = temperature rise. But it’s more complicated that this.
Most ‘climate science’ is not concerned with this central question, which is one of physics and chemistry. It tends to focus more on how to correlate CO2 concentrations with meteorological phenomena, a question of statistics and mathematics.
But it is precisely in answering this question where a ‘fork in the road’ appears. Perhaps surprisingly, there isn’t consensus among the ‘experts’ in related scientific fields as to precisely how it works.
While there is some overlap in some of the detail, it appears that answers to this question can be broadly split into one of two distinct camps which I call
‘direct warming’ and
‘back radiation’.
As far as I can tell, both schools of thought raise as many new questions as they do answer existing ones.
And this is where it gets interesting!
To be able to understand the divergent schools of thought, we must take a slightly deeper look at what each of these ideas entail.
1. Back Radiation
The ‘back radiation’ (sometimes called ‘CO2-forcing’) idea is based on the concept that GHG molecules do not hold on to absorbed radiation like a sponge, but rather, the radiation is almost instantaneously re-emitted back outwards in all directions.
Some of the re-emitted radiation heads back to the Earth, hence the term ‘back radiation’.
As this ‘back-radiation’ hits the Earth it is claimed to give it an additional heating 'boost’.
Since heat from the Earth is one of the primary means by which the atmosphere is heated, additional heating of the Earth from ‘back radiation’ is therefore said to result in a higher atmospheric temperature. A bit like turning up the underfloor heating in a house to warm the air in the room.
You can see the back-radiation component of greenhouse theory in graphical from in this diagram taken from an IPCC technical document.
Problems with the ‘Back Radiation’ idea;
Critics of this idea argue that since you cannot increase the temperature of something with its’ own radiation, this idea is invalid.
You couldn’t cook a chicken by simply inserting it into a mirror-lined box!
Moreover, the laws of thermodynamics tell us that a body of lower energy cannot transfer its’ energy to another body of higher energy. How can relatively cold air, increasingly so as you increase altitude, act as a source of heat for the medium beneath it from which the heat came in the first place?
2. Direct Warming
This idea claims that the radiation absorbed by atmospheric GHG molecules causes a direct warming of the atmosphere. In other words, there is no intermediate step viz-a-viz the extra heating of the Earth as described above by the back radiation idea.
According to the ‘direct warming’ idea, the GHG molecules in the atmosphere become ‘excited’ by the energy being imparted within them. Atoms and their inter-atomic bonds start to vibrate, rotate and stretch.
Moreover, the ‘energized’ GHG molecules are said to undergo substantially increased numbers of collisions with other atmospheric molecules (primarily O2 and N2), whereupon their energy is transferred to them, causing them to vibrate and ultimately heat up.
Problems with the ‘Direct Heating’ idea;
Critics of this idea argue that because GHG molecules themselves make up such a small proportion of the atmosphere (approximately 0.04% in the case of CO2), that having their inter-atomic bonds energized is not a convincing explanation of temperature rise across the wider atmosphere.
The atmosphere is an openly convective system, i.e. able to mix freely, with an almost unlimited capacity to dissipate heat.
How could the energizing of such a small fraction of the atmosphere register a temperature change in openly convective system?
One may therefore look instead for a radiative explanation of heat transfer from the energized GHG molecules to the wider atmosphere as opposed to a convective one.
We know there are unique properties that define GHGs, differentiating them from other components of the atmosphere.
However, a radiative heat transfer explanation means that the re-radiated energy from GHG molecules - that which causes the heating of the surrounding non-GHGs - must somehow differ in its nature to the radiation that is absorbed by and excites the GHG molecules in the first place.
So we now have something like ‘primary’ and ‘secondary’ LWIR bouncing around the atmosphere, with GHG’s changing the properties of the radiation as it transitions from one to the other. Are there also tertiary, quaternary, etc. levels of re-radiated energy with ever changing properties?
This seems to be a somewhat chaotic and ultimately unfalsifiable explanation, and therefore unscientific. Not to mention the proposed concept of ‘radiative saturation’, which says that CO2 and other GHG molecules quickly become limited in their ability to absorb further radiation.
Conclusions; A Brush with the Law (of Thermodynamics)?
Could it be the case that Greenhouse Effect is based on an unfalsifiable theory, such that it can never be directly confirmed by measurement or experiment?
Could it be the case that the climate models have at their core an assumption which contradicts the well established laws of thermodynamics?
I believe that a much greater portion of our collective intellect and resources should be diverted away from more trivial elements of the climate-industrial complex into better understanding these central questions.
But quite astonishingly, the inner workings of Greenhouse Theory are rarely discussed.
Why is that?
Is it because we see these ideas as being ‘settled’? Perhaps, but we have seen in this article how there is anything but consensus on how the theory even works.
Is it because we see these ideas as being inaccessible to most people uneducated in the dark arts of climate science? Perhaps, but the elevation of climate (or any other) science is a recipe for error, hubris and corruption.
When we outsource discussion of scientific issues exclusively to ‘experts’ as a minimum we risk losing perspective; while scientists are often the gate keepers to the tools, methods and esoteric knowledge within their particular fields, they by no means have a monopoly on common sense.
Could it be that the Climate Emperor has, in fact, got no clothes on?
As an atmospheric chemist of some two decades, and while I myself still have much to learn on the topic, I can assure you that these questions of Greenhouse Theory - and many other questions not raised here - are far from ‘settled’.
We must keep on asking questions, real science requires it of you!
I hope you enjoyed,
-Tristan
My analysis ("lay" that it is) diverges completely from the explanations given above. Put simply, isn't the simplest explanation that the absorption of reflected LWIR doesn't, net, heat the atmosphere, as the energy has already entered the system. What it does is simply prevent a *loss* of energy occurring (lowering temperature) because some of this reflected IR does not escape to space? I'm not saying this is correct, but it seems much simpler and less full of holes than the above analysis of various mechanisms.