Saturday 7 November 2020

Skeptical Science neatly disproves its own point with a diagonal comparison

From The Motherlode:

Using Modtran [which matches up well to actual measurements, so let's take this all as accurate], I determined the energy output looking downwards from an altitude of 70 kilometers using the US Standard Atmosphere. The result can be seen on the following graph as the green shaded area. I repeated the model run, but this time with the altitude set at 0 km. The result is shown by the outer curve defining the red area in the graph below.

That means that the red area itself, which is the upwards radiation from the surface minus the upward radiation to space, is the reduction in energy radiated to space because of the presence of Infra-Red absorbing molecules in the atmosphere. That is, it is the greenhouse effect.


It's nothing of the sort and the chart does not show it.

1. The effective temperature of Earth is approx. 255K. That means that skilled astronomers elsewhere in the Solar System - armed only with a telescope - who know nothing about our atmosphere and assume that the white clouds are part of the surface would expect the average surface temperature of Earth to be 255K based on incoming solar radiation, albedo etc. If the astronomers also have an IR-meter, they can measure outgoing IR radiation from Earth and work backwards to find out Earth's effective/average temperature.

They would expect Earth's outgoing IR curve to be just below the pink one for 260K. They will be puzzled as to why measured outgoing radiation is above the 255K line at some frequencies and below it at other frequencies, but overall, it looks 'about right' (these things are apparently insanely difficult to calculate properly).

2a. Why do the Alarmists assume here that Earth's surface would be 288K if it had no atmosphere (like the Moon) and use that as their reference line (the top of the red area shows outgoing IR at an altitude of 0km)? If Earth had no atmosphere, its overall average surface temperature would be below 255K (the Moon's actual surface temperature is lower than its effective temperature, partly because it revolves so slowly and partly because it has no atmosphere).

The extra 33K temperature at Earth's surface is due to the gravito-thermal effect of the atmosphere (and its fairly short day/night length), which has nothing to do with 'radiation', it's just warmer than the effective temperature lower down (and at the surface) and cooler than it higher up. So inevitably it emits more IR lower down (and at the surface) than it does higher up. That's a result of the gravito-thermal effect and not a cause of anything. It's like saying that something that has fallen over caused the force which pushed it; or that a balloon inflated itself.

2b. In the alternative, we could ask why do they assume here that if there were the same atmosphere but with no 'greenhouse gases' that Earth's surface temperature would be 288K (33K warmer than the effective temperature)? Yes, it would be... because of the gravito-thermal effect. But don't they keep telling us that this extra 33K is due to the presence of 'greenhouse gases'? You can't have it both ways.

3. The article concludes with this: "The effect of a particular Infra-Red absorbing molecule, Carbon Dioxide, is clearly visible. With the publication of this data in 1970, the greenhouse effect ceased to be theoretical. It was an observed fact." Yes, the effect is measurable and real. This would explain to our skilled astronomers from 1. why the actual emissions are sometimes below and sometimes above the expected line just below the pink one. So they would conclude that Earth and its atmosphere automatically compensate for the 'missing' or 'trapped' IR at some frequencies by emitting more IR than expected at other frequencies to keep it all in balance (which is what effectively happens).

So it's a diagonal comparison in various different ways, which enables our Alarmist chums to draw exactly the conclusion they wanted before they even bothered with 'evidence'.
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The only counter-counter-argument that I can think of is that the 'missing' or 'trapped' radiation is evidence for additional temperatures at the surface. If that is true, then the 'extra' radiation (above the 255K line) must be evidence for lower temperatures. Which is nonsense, the 'extra' radiation is evidence of a higher surface temperature (higher than effective temperature). So that just goes round in circles, unless you want to have it both ways and claim that both 'missing' and 'extra' radiation are evidence of the same thing (and in which case, of what?).

6 comments:

Andrew Carey said...

Just to help understand, can I offer an extreme example.
Imagine the earth's atmosphere was replaced with 8% butane and 92% ammonia and nothing else, or whatever ratios mean that the atmosphere's molecular weight is the same as now.
Would one expect the surface temperature of the earth to be the same as now?

Mark Wadsworth said...

AC, good question...

1. I think the mix would be 70% NH4 (17 g/mol) and 30% Butane (58 g/mol) to end up with 29 g/mol, similar to 80% N2 and 20% O2.

2. The amount, mass, volume and height of the atmosphere would be the same; surface pressure would be the same, and the two gases would be evenly mixed all the way up (we have to assume).

3. The 70/30 weighted specific heat capacity of the atmosphere would be just over 2,000 J/K/m, so the dry lapse rate would be 4.9 K/km (half what it is now).

4. The moist/real life lapse rate would be lower than that. I'm not sure how to calculate it, so let's call is 3.5 K/km for now.

5. Average temp of atmosphere = 255K and temperature half way up at 5.5 km altitude = 255K (both unchanged).

6. Surface temp would be 255K plus 5.5 x 3.5 = 274K, a lot cooler than now. But the top of Mt Everest would be 10K warmer (or 10K less bloody freezing cold).

7. Average surface temp would be so low as to trigger a really bad Ice Age, so might end up lower than 274K, but all life would have been extinguished by the new atmosphere anyway.

Andrew Carey said...

Thank you Mark, that is incredibly helpful

Dinero said...

Mark there two other issues - the first paragraphs confuses Upwards and Downwards (read the first two paragraphs carefully),
the term of "energy output looking downwards" in the first paragraph becomes "upward radiation to space" in the second paragraph.
Clearly the first direction must be ,up , for the maths of the graph to make sense on its own terms.

Later it states "There is another piece of physics everyone knows. It is that as you go higher in the atmosphere, the atmosphere gets colder." Without any explanation , thus giving no explanation of what most of the topic is about.

Turning to the Gravito-thermal effect. It requires some type greenhouse gasses to happen and so it could be considered as a greenhouse effect itself. Not recognised in the article at all of course.

Mark Wadsworth said...

Din, the up/down does make sense.

"as you go up it gets colder" Agreed on that point.

The gravito-thermal effect does not depend on what the gases are. It's gravity divided by specific heat capacity. That is how it is derived and calculated, no need to take 'radiation' into account. Radiation is a RESULT of temperature, not a CAUSE.

Bayard said...

A perfect example of why climate "science" is closer to scientology than real science. Science starts with data and, from that, produces a theory, then seeks to disprove that theory, using all available data. Pseudoscience starts with a theory, then seeks to prove that theory using cherry-picked data. To quote Arthur Conan Doyle in the person of Sherlock Holmes, "It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts."