by Judith Curry
Martin Hertzberg, one of the authors of Slaying the Sky Dragon, has requested that we assess his paper (published in E&E). Since we had so much “fun” with Part I, I said sure.
EARTH’S RADIATIVE EQUILIBRIUM IN SOLAR IRRADIANCE
The average equilibrium temperature for all the Earth’s entities involved in its radiative balance with the Sun and Space, is given by:
T (e) [K] = 278.9 [ ( 1 – α ) / ε ] 1/4
The controlling factor is the ratio of the absorptivity, a = ( 1 – α ), to the emissivity, ε . The quantity α is the Earth’s albedo. It is shown that relatively modest changes of only a few percent in α, brought about by variations in cloudiness, are sufficient to account for the observed 20th Century variations in Earth’s measured temperature, provided that such variations in cloudiness can cause an imbalance in the ratio ( 1 – α ) / ε . The analysis suggests that in the long run, the absorptivity to emissivity ratio is near unity, as required by Kirchhoff’s radiation law, which ensures a moderate average temperature of about 5.7 C for the Earth’s surface entities. That calculated temperature is in fair agreement with the observed average temperature of those entities, whose mass average is dominated by the mass of the oceans. Except for the influence of clouds on the albedo, no assumptions are needed regarding the detailed composition of the atmosphere in order to explain the observed small fluctuations in the 20th Century temperatures or the larger, longer-term variations of Glacial Coolings and Interglacial Warmings.
As with Part I, I am not going to write a review here. But this one is much simpler than Claes Johnson’s chapter, the only equations are algebraic. And it has a painful misunderstanding of Kirchoff’s Law. But it was published, albeit in Energy & Environment, a journal that is quite erratic editorially (this isn’t to say that the don’t sometimes publish worthwhile papers). So lets give it some attention.
I dismissed reviewing Hertzberg’s chapter in the Dragon book, entitled “History of Encounters with the Sky Dragon.” The chapter stars with a rambling personal history of his encounters, with ample “fear mongering hysteria” etc. It goes on for 30 pages or so, no science.
Moderation note: this is a technical thread, moderated for relevance. Make your general comments on the Part III thread.