Martin, sorry about the delay.

Consider that the lower atmosphere contains water vapour, liquid water as in clouds, ice crystals and other GH gases. This means that it is opaque to IR radiation. It therefore makes no sense to believe that the surface of the earth can be a BB radiator radiating IR to space.

In fact, the radiative equilibrium gives a BB temperature of -18 Celsius. This suggests that the BB surface lies at an altitude of about 5km.

I'll post this and carry on with the explanation.

His mistake is this:

The surface of the earth cannot be considered to be a black body radiator because the atmosphere is opaque to the IR photons.

It's not opaque. You could say "partially transparent", but it's not opaque.

The BB radiatiative surface lies above the clouds and the water vapour because otherwise, unrestricted radiation to space would not be possible. It is true that the process starts with solar, visible light heating the earth surface. BB radiation from there would involve IR photons being blocked by the (ok nearly) opaque atmosphere - it includes clouds of liquid water. (now this IS an aspect of the GHG effect). The energy is transported through the atmosphere in various ways, by convection, kinetic enrgy by way of collisions and so on.

So at this point, the BB radiation, temperature and altitude all match observation and there is an explanation for the altitude.

Now, at the surface, the temperature is about 15 Celsius.

It is meaningless to convert this to an imaginary Stefan Boltzmann black body for the reasons stated above.

Put this another way, if we had no GHG atmosphere, then you can argue that the BB temperature would be the same as the observed surface temperature (15 C). This is the GHG warming argument. But we are now comparing the real world with a false world, because the overall radiative balance would be wrong. The false world has no clouds either, so the balance certainly would be altered.

So the effect of water and clouds is to shift the black body surface to a position in the atmosphere where unrestrict heat loss can proceed. The difference between the BB temperature and the ground temperature is the consequence of the lapse rate, or distance from the heated ground.

An important point in all of this is that clouds (liquid water) also block IR radiation. The CO2 effect must be tiny.

S

BB radiatiative surface lies above the clouds

There is no BB radiative surface, since the TOA is not a black body. It radiates in only a small number of narrow bands.

S,

It's not even '"nearly opaque", it's not opaque at all. The atmosphere doesn't stop (i.e. permanently reflect or absorb) the photons indefinitely, it merely bounces the energy around for a bit longer.

It allows out the same amount of energy in IR photons as arrive from the sun each day in SW photons.

Because IR photons have lower energy than SW ones, it actually allows out a much greater number of IR photons than the number of SW photons is absorbs.

The atmosphere is not opaque to IR in any shape or form.

There is nothing theoretically wrong with GH Theory, and there's very little mileage trying to question it, it's pretty robust science. Where there is a lot of room for doubt is in the magnitude of the GHE and it's overall effect as a single vector in a complex stochaistic system with multiple inputs and outputs, many of which we don't remotely understand or can model, which feed back into each other over time.

The IPCC and climate science is fond of portraying the GH effect as a single huge knob on the climate with a basically linear temperature response (thus the stupid idea of a climate sensitivity). This is undoubtedly plain wrong. The GHE can be absolutely theoretically proven and the idea of a linear temperature response to it be completely idiotic.

S' Cat

The effect of the greenhouse effect is to raise the surface temperature to higher than it would be without one. It is: there is a greenhouse effect and it is about 33 degC. Your 15 degC is wrong – it would be -18 degC but your point about radiating altitude is an interesting one to ponder. If you look from outside our atmosphere there is an engineering formula that's applicable;

Q= ε σ [Te^4 - Ts^4] A

Where Q = Qin = Qout in Watts, emissivity ε is a dimensionless coefficient and σ is the S-B constant. Te is the hotter (Earth in this case) and Ts the cooler (space and therefore a constant).

Climate science believes Qout < Qin with anthropogenic additions of CO2;

Qout = ε σ [Te^4 - Ts^4] A

For that to be true either ε has reduced or A has reduced or the Te to Ts relationship has reduced to satisfy Qout < Qin.

Should ε reduce then that reduction would apply also for absorption as it is commonly held that ε for absorption and emission are the same. A change in ε must be applied to both Qout and Qin and there would be no radiative imbalance.

A is the radiating area of Te which is located at some (average) height in the atmosphere. The lapse rate dictates that height. So for an increase of temperature at the bottom of the atmosphere (Stevenson screen height), A, by geometry, must be greater, not lesser.

If Te were to reduce then the Te to Ts relationship reduces. It is only this that would allow the Qout equation to balance.

I have seen a statement in support of Qout < Qin explaining that as surface temperatures rise then the average height of emission to space rises and that new position will be cooler due to altitude.

“If we add more radiatively-active gases (...) then the atmosphere becomes more “opaque” to terrestrial radiation and the consequence is the emission to space from the atmosphere moves higher up (...). Higher up is colder. So this reduces the intensity of emission of radiation, which reduces the outgoing radiation, which therefore adds energy into the climate system. And so the climate system warms.”

But is that a correct conclusion? Could it not be equally argued that the Te to Ts relationship won't change as the additional altitude is a function of the lapse rate: basically that as the height of emission increases it takes its temperature with it. This in turn increases A which releases more energy to space while restoring Qout = Qin. This new state of equilibrium has a higher bottom of atmosphere temperature endowed by the lapse rate. It is not a radiative imbalance that causes surface warming but is a redistribution of energy between surface(s) and atmosphere. For that to be true, less energy at a surface would endow a lower temperature. The argument against this is that surface temperatures as measured show an increase. However, the surface temperature record is in fact a bottom of atmosphere record from Stevenson screen thermometers. A would be larger.

The “Higher up is colder.” explanation can be tested. If we add, in one short burst, a measurable quantity of CO2, the 'conventional' theory states that Qout becomes less than Qin. That situation has to have a time limit or temperatures would continue to rise for ever and a day. The 'one degree per doubling' takes care of that: the effect is finite. With no further change in the system it would return to equilibrium where Qout = Qin. We would have returned to the status quo of;

Q = Qin = Qout = ε σ [Te^4 - Ts^4] A

Where is the warming?

So what could have led to that “Higher up is colder.” explanation? Is it because Ts is omitted by physicists who calculate that the energy radiated back from space is small enough to be neglected? So that,

Qin > Qout = ε σ Te^4 A

is sufficient together with “Higher up is colder” where Te diminishes to balance the equation with no regard for what may be demanded of it by its relationship with the constant temperature of space.

Just pondering.

mike - Thank you. I'll mull over that.

I think there are two different questions and I don't know which one HDH is talking about.

a. Does the greenhouse effect exist? That is to say, is the surface temperature of a planet higher if its atmosphere contains gases that interact with infrared radiation than it would be if its atmosphere consisted solely of gases that have no interaction with electromagnetic radiation.

b. Can changes of the concentration of CO₂ in the Earth's atmosphere significantly change the Earth's temperature?

When Huffman says the greenhouse effect does not exist, is he referring to a or to b?
Maybe whatever he says is plausible but I have not yet understood what he is saying. (And I confess I find it painful to read what he writes so I'm reluctant to go back again for another view.)

Martin A

I am unsure if A increasing as effective radiating height increases has been discussed but it is certainly something I have alluded to on several occasions. It was not until SoD arrived and I found the quote (shown in my comment) on his site did I realise there was an alternative view. The text below the graphic you link to coincides with his "Higher is colder." explanation. However, the graphic itself does not: it clearly indicates that the temperature at both the CO2 concentrations is the same at around 255 degK. That coincides with my view that the effective radiating height takes its temperature with it as it increases.

Yes I know the magnitude of Ts^4 is negligible against the magnitude of Te^4 but that is not the point. My point is that the rate, Q, is a function of the difference between the temperatures. When Q is fixed, Ts dictates Te. You can't just have a Te that can be anything as long as it satisfies a presumed radiative imbalance.

Shure, the lapse rate varies. The implicit question here is how delta CO2 affects it to a significant extent. I don't know but I do recall a recent study of historical weather baloon data that came to the conclusion that it did not. Perhaps there is something out there that shows that it does?

Mike Jackson

Regarding ice ages, you should research Milankovich Cycles. Unfortunately the hypothesis regards changes in CO2 due to changes in temperature as amplifying the effect. If ou reject the concept that higher CO2 can produce higher temperatures you would automatically reject the Milankovixh hypothesis.

Regarding planetary temperatures, may I think aloud a little.

First simplify by removing all greenhouse gases, so all temperatures are surface temperatures.. Venus has double the insolation of Earth and Mars roughly half. Since IR outward radiation increases as the 4th power of temperature Venus would be about 15K warmer than Earth and Mars 15K cooler. perhaps 270K, 255K and 240K respectively.

Pressure is irrelevant. Everybody associates a changing, increasing pressure with increasing temperature from the Gas Law, but a planetary atmosphere is more or less at equilibrium and will stabilise at whatever temperature other factors produce.

Now add water to Earth. This will act as a greenhouse gas and increase the temperature to, perhaps, 260K. Venus and Mars have negligible atmospheric water and are unaffected. Temperatures are now 270K, 265K and 240K.

Now add CO2. Mars has an atmospheric pressure of 0.01 bar and 95% CO2. That is roughly 230 times more CO2 molecules per cubic metre than on Earth. Roughly four times the greenhouse effect on half the insolation, call it 15C.
That brings Mars up to 255K.

Earth's CO2 greenhouse effect is generally reckoned to be 33K. That brings Earth to 298K.

Venus is at 90 bar and 95% CO2. It has 2,185,000 times more CO2 molecules per cubic metre than Earth. I' m getting close to my cognitive limit here. Lapse rate temperature change 10 times Earth, call it 300K? DWLR 1000 times Earth, call it 15000W, call it 375K. Temperature becomes 270 +300+ 375K=945K

Compare these with reality. For Mars I got 255K, versus real temperature around 225K.

For Earth I got 298K versus a real 288K.

For Venus I got 945K versus 733K.

That was fun, and without using any extra mechanisms!

Mike Jackson, Radical Rodent

Wrong way round. The existing physics is sufficient to explain the behaviour of the system, therefore there is no need to invoke new science. Occam's Razor!

Those doing so, such as Huffman and yourselves, want CO2 science to be wrong and therefore keep inventing alternative explanations. The snag; none of them have supporting evidence.

Keep trying. If you can come up with enough evidence to force a paradigm shift, I'll cheer you on. Until then, I'll stick with the CO2 greenhouse effect as the best available match to reality.

Richard Blake

How do you define dangerous?

The population of Japan facing more frequent landslides would define it as dangerous.

The US citizens and Canadians dying in more frequent forest fires would define it as dangerous.

The population of California facing drought would define it as dangerous.

The population of Pakistan facing more frequent floods would define it as dangerous.

The government of Egypt overthrown after food riots would define it as dangerous.

The Inuit drowned by changing ice conditions would define it as dangerous.

The Canadians and Siberians whose infrastructure is collapsing as the permafrost thaws would define it as dangerous.

Those dying in the wars in the Horn of Africa as rising population meets declining agricultural production would define it as dangerous.