The Unassailable Radiative Physics of the Greenhouse Effect

Raymond Pierrehumbert concludes his featured article in Physics Today Infrared Radiation and Planetary Temperature by:

• The basic radiative physics of the anthropogenic greenhouse effect is unassailable.

The greenhouse effect is described as follows:

• Adding more greenhouse gas to the atmosphere makes higher, more tenuous, formerly transparent portions of the atmosphere opaque to IR and thus increases the difference between the ground temperature and the radiating temperature.
• The result, once the system comes into equilibrium, is surface warming.
• The effect is particularly spectacular for Venus, whose ground temperature is 730 K. If the planet were a blackbody in equilibrium with the solar radiation received by the planet, the ground temperature would be a mere 231 K.

The article is hailed by Judith Curry:

• Raymond Pierrehumbert has written an excellent overview on infrared radiation and planetary temperature.
• So, if you have followed the Climate Etc. threads, the numerous threads on this topic at Scienceofdoom, and read Pierrehumbert’s article, is anyone still unconvinced about the Tyndall gas effect and its role in maintaining planetary temperatures?
• I’ve read Slaying the Sky Dragon and originally intended a rubuttal, but it would be too overwhelming to attempt this and probably pointless. Has anyone else read this?

What to say about this?

First, Pierrehumbert by claiming that certain radiative physics is "unassailable" (impossible to dispute) and as such makes also the greenhouse effect impossible to dispute, in fact admits that he seeks to fool people by presenting a definition as a physical fact.

A no-feedback climate sensitivity of of 1 C is also unassailable, because it is a definition disguised as a physical fact.

That Venus high temperature depends on a greenhouse effect is easy to assail: It depends on a high thermodynamic lapse rate determined by the high pressure of the thick atmosphere and is not an effect of radiation.

Second, Curry claims that she has read Slaying the Sky Dragon: Death to the Greenhouse Gas Theory, but finds it "too overwhelming" and asks for help: Is it perhaps so overwhelming even to the Sky Dragon, that it is almost unassailable? Is the slaying or assail effective and therefore not pointless?

Compare with the true story about Tyndall and His Greenhouse Effect.

PS Also Roger Pielke Sr endorses Pierrehumbert's unassailable greenhouse effect, as another skeptic confused by IPCC CO2 alarmism.

Skeptics Missing the Main Argument, Unfortunately

Both Anthony Watts (WUWT) and Lubos Motl (Reference Frame) comment on Kevin Trenberth's upcoming talk at the American Meteorological Society meeting on Jan 26 on Communicating Climate Change with the thoughtful title ClimategateThoughts.

Watts and Motl are a bit skeptical to Trenberth, but they seem to accept the energy budget of Trenberth underlying CO2 climate alarmism, discussed at length on this blog.

The following questions present themselves:

• Why are Watts and Motl not skeptical to the backbone of CO2 alarmism: Trenberth's energy budget?
• Why are Watts and Motl ignoring the devastating analysis of Trenberth's budget presented in Slaying the Sky Dragon: Death to the Greenhouse Gas Theory or Death to Trenberth's Energy budget? Is the math there overwhelming?

In short, why are skeptics not skeptic? Maybe because they view themselves as physicists, and

physicists believe in the "greenhouse effect" and Trenberth's energy budget.

Watts and Motl are joined by Lindzen and Spencer as "skeptic physicists" confessing to the "greenhouse effect" with a miraculous ability of turning a thin atmosphere into a "heat-trapping blanket". There must have been something seriously wrong with physics education during the 20th century.

Here is the basic belief to which Lindzen confesses:

• It is generally acknowledged that simply doubling CO2 should lead to a warming about 1 degree Centigrade.

Lindzen does not understand that here "general acknowledgement" is achieved by making this

statement into a definition of no-feedback climate sensitivity. Lindzen does not want to know that a (generally acknowledged) definition does not say anything about any reality, but is just a play with words, as empty as saying that there are 100 centimeters on 1 meter.

This is unfortunate because CO2 climate alarmism is based on this no-feedback sensitivity of 1 C, which then is argued to possibly become an alarming 3 C by positive feedback.

But you cannot get anything from a definition and without the 1 C to start with, the real game has to start with 0 C and this feedback game is completely open, as explained in Climate Feedbacks with Nothing to Feed On. It is not even clear if more CO2 will cause cooling, or warming or nothing.

It is unfortunate that a skeptic physicist like Lindzen does not appear to be willing to see this, (and therefore feels obliged to invent negative feedback which may be questioned). Why? Lindzen can't be so stupid that he can't see the trick used to create climate alarmism out of nothing, from a definition. But why is he willing to interprete a definition as a physical fact?

Lindzen is in good company with Judith Curry:

• Well, burning fossil fuels and other anthropogenic activities have undoubtedly changed the climate and even weather patterns, the butterfly flapping its wings in Brazil, and all that.

And all that: Anything is possible in physics science fiction.

What is the cost of the fiction, in the US? About $4 billion next year into climate change

research (NSF 1.6, DOE 0.6, Nasa 0.4, NOOA 0.4, DOI 0.2). Enough to pay 40.000 full-time

researchers. A good size army.

Of course peanuts compared to the $14 trillion of federal budget deficit. Anyway, what about say $1 billion to skeptic climate science? About 10.000 full-time skeptics. And it would be well spent money, since it could save the $4 billion. Maybe something for new Congress looking for cuts?

PS Lindzen repeats his mantra in A Case Against Precipitous Climate Action:

• However, the contribution of increasing CO2 alone does not, in fact, lead to much warming (approximately 1 deg. C for each doubling of CO2).

Lindzen does not understand that this mantra is precisely what underlies "Precipitous Climate Action" and so his argument is rather for than against doing something drastic quickly.

Climate Feedbacks with Nothing Real to Feed On

Without anything real to feed on because of deep snow, deer are now starving to death...

IPCC climate alarmism is based on a climate sensitivity of 3 C from doubled CO2, presented as the result of feedbacks starting with an initial value of 1 C.

In a survey of IPCC climate science, (former) IPCC scientist Judith Curry has now come to the basic question of Climate Feedbacks:

• Everybody talks about climate feedbacks, but what are they, really? And where did the expression ΔTs = λRF actually come from?
• After two decades of wrestling with this issue, I’m not sure how useful the concept of “feedback” is in the context of the climate system.
• We already saw what kind of trouble we can get into on the thread on CO2 no feedback sensitivity, which is supposed to be the easy part of the problem.
• The problem flat out isn’t linear, and attempting to do a nonlinear control theory analysis is pretty hopeless, as illustrated by the Aires and Rossow paper.
• At best, it seems like the concept is useful as a conceptual aid in thinking about a complex system. Various metrics like ΔTs = λRF or the partial derivatives may have some use in comparing climate models with each other or with observations, but it may not say much about feedback.
• So is this concept useful? If not, can it be salvaged?
• Or are there better ways to try to understand the whole system, something from dynamical systems theory, entropy extremals, etc?

We read that Curry poses questions but we see nothing in the direction of answers.

Curry asks the logical question: If now both the sign and magnitude of feedbacks are

impossible to determine, why was the concept introduced at all?

Because it served IPCC climate alarmism, of course, but there is one important element to understand: Feedbacks need something to feed on, an initial perturbation which can be magnified by positive feedback. So what was then the initial perturbation and how could it be identified by IPCC if nothing else could?

The answer is given in my recent post Definition vs Axiom and Consensus in Climate Science

showing that the initial value to feed on by IPCC is stated to be 1 C, referred to as no-feedback climate sensitivity.

So how is then the initial value of 1 C as no-feedback climate sensitivity determined? By experiments? No, that is impossible. By a theory starting with some assumptions which can be verified? No, nobody knows such a theory.

What remains is to take 1 C as a definition of no-feedback sensitivity to be computed by a

direct application of Stefan-Boltzmann's Black-Body Radiation Law with certain data ("radiative forcing" of 4 W/m2), which invariably gives 1 C.

The advantage of a definition is that full consensus can be reached: It is pointless to question if there are 100 centimeters on a 1 meter. It is pointless to question a no-feedback climate sensitivity of 1 C computed from Stefan-Boltzmann's Law with certain data. That would be like questioning that there are 200 centimeters on 2 meters.

IPCC thus can safely state that there is full consensus about a no-feedback climate sensitivity of 1 C, because it is a definition.

So, a definition is wonderful in the sense that full consensus can be reached as concerns its validity. But the full consensus and absolute truth of a definition does not come without a serious drawback: A definition says nothing about reality.

If we understand this, we understand that the IPCC feedbacks have nothing real to feed on, and

thus cannot say anything about any reality. Curry has understood this, maybe. Anyone else?

For example, what about Lindzen and Spencer? Are they happy to twist, like IPCC, a definition into a potentially alarming physical fact of 1 C, and then have to argue that negative feedback can diminish it to a harmless 0.5 C, using an argument that can easily be questioned? Is this clever? Is it science?

It must be possible for a scientist to understand if a certain statement is a definition, which is true by its construction independent of any reality. Or if it is a statement about reality which may be true or false depending on the reality and therefore can be questioned, because perceptions of reality can differ and thus possibly prevent full consensus.