By Denis G. Rancourt
Former physics professor, University of Ottawa, Ottawa, Canada.
Abstract – I describe the basic physics of planetary radiation balance and surface temperature, using the simplest model possible that is sufficiently realistic for correct evaluations of predicted surface temperature response sensitivities to the key Earth parameters. The model is constrained by satellite absolute integrated intensity and spectroscopic measurements and the known longwave absorption cross section of CO2 gas. I show the predicted Earth temperature for zero atmospheric resonant absorption of longwave radiation (no greenhouse effect in the otherwise identical atmosphere) to be –46 C, not –19 C as often wrongly stated. Also, the net warming effect from the atmosphere, including all atmospheric processes (not just greenhouse forcing), without changing anything else (except to add the removed atmosphere) is +18 C, not the incorrect textbook value of +33 C. The double-layer atmosphere model with no free parameters provides: (a) a mean Earth surface temperature of +17 C, (b) a post-industrial warming due only to CO2 increase of δT = 0.4 C, (c) a temperature increase from doubling the present CO2 concentration alone (to 780 ppmv CO2; without water vapour feedback) equal to δT = 1.4 C, and (d) surface temperature response sensitivities that are approximately two orders of magnitude greater for solar irradiance and for planetary shortwave albedo and longwave emissivity than for the atmospheric greenhouse effect from CO2. All the model predictions robustly follow from the straightforward underlying assumptions without any need for elaborate global circulation models. The same longwave optical saturation that provides such a large radiative warming of the planet surface also ensures that the warming effect from increasing CO2 concentration is minimal. I conclude with suggested implications regarding warming alarmism, errors by sceptics, research funding, and scientific ignorance regarding climate feedbacks.
Historically, the greatest ability of the physicist has been to perform simple calculations that capture the essential features of a physical phenomenon in order to correctly elucidate the underlying principal causes. This is the ultimate “What is going on?” challenge.
Too many practicing physicists, in the many areas where physics is applied, have lost or never had this ability. Instead, they have been incorporated into the enterprise of using computers to simulate reality using questionable selections of approximate or invalid algorithms in large simulation programs.
These programs develop lives of their own, as careers and reputations are invested in their incremental development and in their predictions. A pathological optimism envelops the practitioners with the illusion that their algorithms capture complex features in some “average” or “effective” way and efforts are made to demonstrate this in so-called “validation” exercises rather than perform simple calculations that would demonstrate the algorithms themselves to be wrong for the intended application.
Physicists have largely abandoned their gadfly role of fundamentally challenging broad interpretive schemes in order to serve and benefit from career-enhancing collective enterprises, often dressed in elaborate conceptual edifices and often supported by computer simulations.
I believe this situation is playing itself out today in climate modelling science. As a physicist, if on close examination I can’t understand what the CO2 warming alarmism is about and I can’t get any of my colleagues to explain it – without computer-black-box magic, in published papers or elsewhere – then I am not going to believe it.
At its core, planetary surface temperature is a macroscopic radiation balance phenomenon that has been understood for one hundred years or so. If global warming alarmism is justified then it must be possible to explain why it is justified in simple terms and without appealing to faith or authority for any essential point in the argument.
I’ve tried to do this, as honestly and openly as possible, and I have asked my peers to find any errors. I believe the present article to be error-free and to conclusively show that we should not be focussed on CO2 if we are concerned about the planet’s surface temperature. I am additionally of the opinion that we should not be concerned about the planet’s surface temperature.
Regarding the sceptic-warmist debate, my conclusion is: The sceptics say many incorrect things but they are right whereas the warmists say many correct things but they are wrong. The skeptics appear to be motivated by skepticism whereas the warmists appear to be motivated by conformism. The incorrect things have been used to discredit the sceptics and the correct things have been used to mask a lie.
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(With small clarifications added and some typos corrected on December 3, 2011.)