Miguel:
And what papers/reports does that source refer to, that supposedly modeled the problem the way the book tries to refute it (flat disks, etc.)? The only reference in that chapter is to moon facts (Moon Fact Sheet ).
If there is nothing else, it’s refuting a strawman model…
Well, here was my response to being presented with the link to these chapters, which I wrote about 2 1/2 days afterwards:
I read these chapters with great interest and my initial reaction was that how can it be so amazingly simple how completely wrong the basis of the AGW theory is?
I didn’t just believe it though, so I dug in. The geometric argument seems to check out but I’m not sure about some of the others.
Re the geometric one… one of the doubts was that this was how it was actually done in climate science, but:
I googled “earth -18 c temperature” and the second link was to a Wired article from Feb 3, 2023 titled “What Would Earth’s Temperature Be Like Without an Atmosphere?” (link ) , which reaches approximately that figure of -18C (actually in the article it’s -13.2 C but it’s close enough for these purposes), and this snippet (emphasis mine):
Also, notice that this is quite a bit colder than the actual average temperature of the Earth (13.9 C)—a 27.1-degree C difference. That’s because the Earth isn’t actually a bare rock. Instead, we have an awesome atmosphere
I googled “Kiehl-Trenberth” and found this paper “Earth’s Annual Global Mean Energy Budget” (link ), where on the page labeled 206 they have a figure showing “Incoming Solar Radiation” as 342 W m-2 (i.e. the dividing by 4). And Trenberth is a prominent figure: “Kevin Trenberth has been prominent in all aspects of climate variability and climate change research and is a leader in the Intergovernmental Panel on Climate Change assessments and in the World Climate Research Programme.” (source )
I googled “climate change blackbody” and got a link to a Powerpoint that describes it exactly as laid out in the book - https://cires.colorado.edu/outreach/sites/default/files/2018-12/Fairall%20lecture%20note%20taking%20(Module%202).pdf . So this is how it is taught.
http://assets.press.princeton.edu/chapters/s9636.pdf then I found this which on page 15 shows the diagram of the surface receiving more total energy than it gets from the sun due to the atmosphere radiating some of the energy back down.
This all satisfies me that this is indeed how it’s done.
Then as to whether the argument itself is right…
Firstly, about dividing the sunlight hitting the earth by 4. In the Wired article (and other sources I found) they don’t explicitly divide 1368 watts/M^2 by 4. They just map “energy in” to “energy out” via this equation:
The energy in isn’t divided by four – it’s just the energy the sun receives from the Earth, which is the amount of m^2 of surface area that the Sun ‘sees’ when shining on the earth, which is the shape of a flat circle with the earth’s radius. This part seems simply true — the energy has a certain intensity of energy (watts) per square meter, and whatever amount of the Earth is exposed to the sun, that’s how much energy it gets. Whether the Earth were a flat disk of radius R perpendicular to the sun, or a cylinder of radius R and height 50,000 miles extending out of it — the net surface area exposed to the sun is the same, so this is the total rate of energy received from the sun.
Then they make the assumption that the Earth radiates energy out across its own spherical area evenly. Here is where we get the factor of 4 (which would be 1 if a flat disk, ‘h’ of the height of a cylinder if it were a cylinder, but it’s 4 for a sphere). Mathematically it’s equivalent to dividing the net energy in by 4, but the motivation is different and Siddons seems to arrive at it backwards.
However his point still stands because this “energy out” equation assumes the entire Earth radiates evenly, i.e. has one average temperature. Because of the 4th power relation of radiance and temperature, this doesn’t make any sense at all. The effect literally is as if to treat it as a flat disk with 4x area, for the purpose of radiating the energy out. Further as shown on the “Earth’s Annual Global Mean Energy Budget” paper I see that climate scientists do take the shortcut and just divide net energy by 4, because it is mathematically equivalent, so the point is fully vindicated
Of course they have made computer models later with a 3D Earth etc., but the equations they use to determine what happens on their 3D-model Earth, are based on the mathematical model of the flat Earth. It’s where the concept of ‘radiative forcing’ of CO2 levels comes from… which anyone can find out for themselves by looking into the matter.
One may wonder why such a difference in reactions to being presented with the link to the chapter… I direct anyone with such a wonder to the Stepping Back (re: global warming) post as a possible explanation.
Cheers,