I've touched on atmospheric backradiation before, back when I was trying (unsuccessfully) to construct my own simple computer simulation model of global warming.
In rough outline, Anthropogenic Global Warming (AGW) is supposed to work by short wave solar radiation passing through the Earth's atmosphere and being absorbed at the surface of the Earth, and warming this surface, and being re-radiated back out into space as long wave radiation, some of which is captured by carbon dioxide in the atmosphere, which is warmed, and in turn re-radiates this heat as "backradiation" to the Earth's surface, warming it a little more. This extra warming is AGW. And the more carbon dioxide in the atmosphere, the greater is this warming.
But some physicists object that this "backradiation" is unphysical, in that it requires heat to be transferred from the cold atmosphere to the warm surface of the Earth, and the Second Law of Thermodynamics disallows heat from flowing from cold to warm. From The Science of Doom
What’s amazing about back-radiation is how many different ways people arrive at the conclusion it doesn’t exist or doesn’t have any effect on the temperature at the earth’s surface.
It seems that this "backradiation" is a feature of quantum physics, whereby energy is supposed to be released in discrete packets called "quanta". The quantum physical view is said to have been developed by Max Planck in about 1900 in an "act of despair" in order to get round the "ultraviolet catastrophe" whereby the classical wave mechanical understanding of radiation embodied in the Rayleigh-Jeans law predicted an infinite (and therefore impossible) energy content of high frequency radiation. Planck's new quantum mechanical understanding did not produce this "ultraviolet catastrophe", and produced a theoretical result much more closely in line with the observed radiation spectrum (see right
The result has been a somewhat schizophrenic "wave-particle dualism" in physics ever since, with radiation being regarded as made up of waves for some purposes, and as particles or quanta for other purposes.
But according to Claes Johnson
, a Swedish professor of mathematics, the classical wave mechanical view of radiation, which Planck had abandoned in order to circumvent the "ultraviolet catastrophe", can actually be used to get round the problem, by using finite precision mathematics.
A black body is regarded a vibrating string
, with a number of harmonics, but with a cut-off minimum wavelength, representing the smallest wavelength the string can carry. Incoming waves excite the string harmonics, and these harmonics are re-radiated. High-frequency waves, with a shorter wavelength than the cut-off, are absorbed as incoherent high frequency vibrations which take the form of heat.
The net result is that a warm blackbody can heat a colder blackbody, through incoming frequencies above cut-off. But a cold blackbody cannot heat a warmer, because incoming frequencies below cut-off will be re-emitted without heating effect.
Since "backradiation" refers to the latter case, the model indicates that "backradiation" is not physical.
And if "backradiation" is unphysical, then it can't be happening. And if that can't be happening, neither can Anthropogenic Global Warming. And then AGW will prove to have been the product of the misdirection of physics by Max Planck in 1900 in his attempt to circumvent the problem of the "ultraviolet catastrophe". It may well turn out that the AGW problem has been a consequence of an unfortunate dualism within physics that has grown up over the past 100 years.
AGW devotees may then be seen as being followers of Max Planck ("Planckists?"), and of the orthodox quantum physics of the past century. AGW sceptics such as Johnson may be seen as followers of the older classical wave mechanical view of radiation ("Maxwellians?"). A dispute within physics has spilled out into a high-stakes political conflict.
If so, it will only be physicists - and not politicians or anybody else - who will ultimately be able to resolve the dispute. Either that, or the actual behaviour of the Earth's climate will prove or disprove one party or the other. Since more or less everyone agrees that the Earth has been warming over the past century or so, during which period carbon dioxide levels in the atmosphere have been rising, the Planckists have a fairly good case that the Earth's climate is following Planckist directions. However the fact that it doesn't seem to have warmed at all over the past 13 years suggests that the climate is perhaps more Maxwellian than Planckist.
By no means all AGW sceptics deny the existence of "backradiation". Most sceptics are as Planckist (and orthodox) as AGW believers. Their scepticism is not about the fundamental physics so much as the scale of its effects and the nature of other feedback mechanisms.
This month, however, in the wake of the publication of Slaying The Sky Dragon
, of which he is a co-author, Claes Johnson has been subjected to censorship
by Swedish university authorities:
The highly-experienced and respected professor has been banned by his bosses from teaching any “part of course material in the course Numerical Methods II.” The material is also found in his ebook, ‘BodyandSoul.’
Dr. Johnson laments, “the course, has been “stopped” by the President of the Royal Technological Institute KTH, because the book contains a mathematical analysis of some models related to climate simulation.”