July 21st, 2010


Mysterious Back-Radiation

In recent weeks, I've been trying on and off to build my own simple climate simulation model. It all began with the suggestion that global warming was taking place on the Moon (which doesn't have an atmosphere), and that NASA had known about it since the 1960s. The Moon was actually warmer than it was supposed to be.

My own conclusion, after writing my own little simulation model, was that there was no big deal. Back in the 60s, they'd just worked it out wrong, and then corrected their mistake.

After I'd created this little simulation model, I wondered whether I could add an atmosphere to it, and have a look at the greenhouse effect, whereby the Earth, warmed by the sun's rays, re-radiates that heat back into space, with some of it getting captured by CO2 and other greenhouse gases in the atmosphere. I started hunting around looking for information about how to work out how much re-radiated heat got captured by greenhouse gases. With that, and a few reflective clouds floating on top of the atmosphere, I'd be able to get an idea of what was going on. It was all physics, of course, but I have some experience of the physics of heat flow - after all, I used to do research into heat flow in buildings a long time ago -.

I thought it would all be fairly straightforward. But it rapidly became mysterious. It turned out that what was supposed to be happening was that some of the heat re-radiated from the warmed surface of the Earth was captured by CO2 molecules, and then shortly afterwards re-radiated by the CO2 molecules either up into space or back down onto the surface of the Earth. At the level of quantum mechanics (yes, I'm out of my depth there too!) a photon of light of a particular frequency would be absorbed by a CO2 molecule,back-radiation which would enter an excited state, with its internal bonds stretched or otherwise flexed, before releasing a photon of light in some random direction - which in practice meant that 50% would go up, and 50% down (see A at right). This started me thinking about Photon Football, with photons like footballs being captured by CO2 footballers and passed about.

I also noticed that some sources said that it wasn't a 50-50 balance between up and down, but more like 60-40, with more radiation going down than up. At one point I even came across the suggestion that 90% of the radiation from the Earth's surface captured by CO2 got re-radiated back to the surface of the Earth. How could that be? But I soon realised that if the atmosphere was not treated as a single sheet of material (the light blue line) but as several layers (see B at right), then the more layers that were added the less radiation ever got out into space. It would keep bouncing around in the atmosphere. With enough layers of CO2, the atmosphere would behave like a mirror, reflecting nearly all the heat back in - much like a thermos flask -. I could begin to see where those 60% and 90% figures were coming from.

So far, so good. But as I kept digging, I began to come across people who were objecting to the whole idea that this 'back-radiation' was happening at all. Claes Johnson, a Swedish professor of applied mathematics, was saying that this back-radiation violated the Second Law of Thermodynamics - which says, very roughly, that heat flows from hotter to colder bodies -, because it required the cold atmosphere to heat the warm surface of the Earth. It would be like your cold feet making a hot water bottle hotter, rather than the other way round. Claes Johnson asks:

Why do physicists keep silent?

And the answer, it seems, is that physicists don't know anything about the greenhouse effect, because it's not in physics textbooks (I checked my college physics textbook, and there was nothing about it there). In the comments, the physicist Anders replies:

The first and foremost is, as you say, they don't read about the Greenhouse Effect in the physics literature. Secondly, most physicists are not political activists to their nature, and sadly, most of them don't pay much attention to what is going on in other branches of physics than their own.

Physicists, it seems, know about as much about the greenhouse effect as I do.

And there are now people who are saying that the whole 'greenhouse effect' is a complete invention, and it simply isn't happening at all.

I'm in no position to judge, of course. Most sceptics seem to think that there is a greenhouse effect, but it's small. But there seem to be a growing number of physicists and mathematicians who are insisting that there isn't one.

If they're right, it's far bigger deal than Climategate. It won't just be climate scientists enmeshed in controversy, but the entire flagship science of physics. Controversies over whether light is made up of waves or particles, and the direction of time's arrow, and the nature of entropy, will burst back into life. People will wonder what we know about anything, as rival professors of physics, and theorists of quantum mechanics, slug it out on TV.

On Monday, one of the principal figures in the global warming controversy, 65-year-old Stephen Schneider, died of a heart attack on a plane landing at Heathrow. He was one of the pioneers who developed climate simulation models. It could just be that his number was up, and he was always destined to die that day. It could also be that he was under enormous pressure as a climate scientist already, and that pressure was getting worse. Add to that the stress of landing in a jet at Heathrow. Schneider may well have been a casualty.

It goes deeper. Quoting a variety of physicists, Claes Johnson asks:

Does anybody understand thermodynamics?

Every mathematician knows it is impossible to understand an elementary course in thermodynamics. (V. Arnold)

...no one knows what entropy is, so if you in a debate use this concept, you will always have an advantage. (von Neumann to Shannon)

As anyone who has taken a course in thermodynamics is well aware, the mathematics used in proving Clausius’ theorem (the 2nd Law) is of a very special kind, having only the most tenous relation to that known to mathematicians. (S. Brush [8])

Where does irreversibility come from? It does not come form Newton’s laws.
Obviously there must be some law, some obscure but fundamental equation. perhaps in electricty, maybe in neutrino physics, in which it does matter which way time goes. (Feynman [9])

Climategate may well turn out to have been the first rumble of thunder in a colossal storm which is going to engulf the whole of science, and have profound effects on how it's done, and what's called 'science' and what isn't. There'll be calls for a thorough reformation of science, and the ejection of pseudosciences of every kind.

One of which, of course, is the Nazi antismoking 'science' which is being used to demonise smokers and close pubs and destroy communities.

It might be a good idea to stock up with popcorn. And mug up on the Second Law of Thermodynamics, and the nature of electromagnetic radiation, and the direction of time's arrow. Because you may well be hearing an awful lot more about them soon.

Further reading: John O'Sullivan, the Hockey Schtick. American Thinker, Climate Change Fraud

PS. 24 July 2010 update: Dr Roy Spencer on how cool objects can make warm objects even warmer.