JoNova

A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


The Skeptics Handbook

Think it has been debunked? See here.

The Skeptics Handbook II

Climate Money Paper


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GoldNerds

The nerds have the numbers on precious metals investments on the ASX



A discussion of the Slaying the Sky Dragon science: Is the Greenhouse Effect a Sky Dragon Myth?

 ”Skeptics” are described as if they are one small block of  fringe extremists, but not only is half the population skeptical in some sense, in this debate I am not on either extreme, but a centrist, smack in the middle. On the one hand, alarmists are convinced the climate is headed for a catastrophe, and on the other some people are convinced there is no greenhouse effect at all. Wes Allen, sits in the middle with me, and he’s been engaged in an intense debate with people on both ends of the spectrum. After a scorching critique of Tim Flannery’s work, he has swung his attention the other way. Here is his synopsis of the Slayers book, for discussion, and I’m sure it will generate a long passionate defence and debate, just as previous posts on this topic have. (eg: Why greenhouse gas warming doesn’t break the second law of thermodynamics and So what is the Second Darn Law?). I know the Slayers are keen to discuss their ideas. I’m hopeful people can remain polite, as that’s where progress may be made… many thanks to Wes here who has done a diligent write up, and has gone to great [...]

Do greenhouse gases warm the planet by 33°C? Jinan Cao checks the numbers.

Jinan Cao has been dissecting the nature of the greenhouse effect and a key calculation that I normally just accept without questioning. This will set a few pigeons loose, but it will be interesting to see where they land. The claims analyzed here are the oft repeated ones that the Earth’s greenhouse effect already warms us by 33°C and that a doubling of CO2 directly causes a 1.1°C rise (that’s with no feedbacks taken into account).

Jinan points out that these numbers, repeated as “fact”, are merely a result of misuse of the Stefan-Boltzmann equation. If Earth is not a perfect black body, but has an emissivity of 0.7 (as satellites suggest), then the temperature of the planet’s surface without any greenhouse effect would not be -18°C, but more like 5°C. That would mean the entire warming due to the greenhouse effect is only around 10°C, not the more impressive 33°C that is usually claimed. It means the greenhouse effect is probably less important than implied.

The 1.1°C direct rise that is predicted from doubling CO2 without feedbacks would also need to be recalculated. This paper does not try to do that, but if Jinan is right, that figure would [...]

Why greenhouse gas warming doesn’t break the second law of thermodynamics

This is generating many comments, see below for an update!

Behind the scenes some skeptics are suggesting that CO2 can’t warm us because the atmosphere is colder than the planet, and  it would break the 2nd Law of Thermodynamics (see Postma*, for example, p 6 – 7). I disagree. The 2nd Law of Thermodynamics applies to net flows of heat, not to each individual photon, and it does not prevent some heat flowing from a cooler body to a warm one.

Imagine three blocks of metal side by side. They are 11°C, 10°C, and 9°C. Think about what happens to the photons coming off the atoms in the middle of the medium temperature block between the other two. If heat never flows from cooler blocks to warmer blocks, all those photons have to go “right“, and not ever go “left”, because they “know” that way is towards a cooler block? (How would they?!)

The photons go both ways (actually every way, in 3D). There are more coming from the 11°C block to the 10°C block, sure, but the the 10°C block is sending ‘em back to the 11°C block too. So heat is flowing from cold to hot. It happens [...]