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CO2 Warming? The Lab vs. The Atmosphere

How many times have we been told that the consequence of an increase in CO2 concentration has to be an increase in temperature because laboratory studies have incontrovertibly shown the “greenhouse” nature of CO2 (and other gases)?

And yet, the (negative) reply to those claims is very simple.

Everybody can incontrovertibly verify in their own kitchen that warmer air moves upwards, and colder air downwards. We can call that the “greenhouse” nature of height, to be  translated in mathematical models whose runs will surely convince some climate scientists about the existence of sizzling mountaintop conditions.

Now just imagine going up the K2 or the Aconcagua with such a climatologist, endlessly referring to progressively cooler temperatures as “noise masking the overall warming trend”…


To anticipate the usual comments: the above cannot be used to disprove the greenhouse effect of CO2 in the atmosphere. But it shows that such an effect has to be proven in the real world, rather than on paper simply by reference to what is found in laboratories and using theoretical physics.

0 replies on “CO2 Warming? The Lab vs. The Atmosphere”

We are told that rising global temperatures will result in an increase of atmospheric water vapour which is the main greenhouse driver providing the positive feedback to disaster.

So why has the global relative humidity at the 300mb level declined by more than 20% from 1948 to 2000? The 300mb level, around 7 kilometers up, is the level where outgoing long wave radiation has very little chance of being recaptured. It is also the level of the missing “hotspot”.

I can’t see how arguing the physics is credible unless you’re an atmospheric physicist… the Earth climate system is complex and simple counter arguments lack credibility. I.e., “if you think x should happen that’s because you don’t understand water vapour feedback…” etc. This is fair point, I think.

You can argue the theory of what a new drug should do to treat a patient, but the human body is also complex and unanticipated interactions may cause that theory to go out the window. So you make predictions and run a drug trial.

The IPCC has made predictions and the trial is the averaged global temperature trend. So everything stands or falls on the long term direction of that trend.


I agree with you. My point is that the question “will additional CO2 warm the atmosphere?” cannot be answered with a simple “yes because a GH effect for CO2 has been observed in the lab”…exactly like no drug can be declared effective just “because it works well in vitro”

Actually the doubling of CO2 only causes the increase in temperature you stated if it is the only greenhouse gas present. In the atmosphere however, the main greenhouse gas is H2O. Thus the theoretical effect of increasing CO2 depends on how much other GHGs are present, especially H2O. This is why increased CO2 would theoretically cause a greater temperature increase in areas with low atmospheric humidity such as the poles. In areas with high humidity doubling the CO2 does not double the GHGs, but adds very little to the total GHGs and thus has minimal effect. The alarmist climate models achieve greater climate sensitivity to CO2 by assuming a positive feedback from increased H2O. Many scientists disagree with that assumption.

You’re right – the CO2 lab experiments are simple, the climate is complex, the two cannot be easily compared.

IRC? It should be IIRC. If I Recall Correctly.


If I Can Type Correctly.

I seem to recall that the “basic physics” suggests warming for a doubling of CO2 of around .5c. The extra warming predicted by the IPCC is based on theoretical models that themselves appeal to temperature changes over time, as the dynamics of the climate system are not entirely understood. If “real world” measurements were not being factored into the computer models, there would be no basis for alarm.


I think it’s 0.65C. You are right, CO2 physics on its own is not enough for any panic. And as the effect is logarithmic, the first 400ppmv are as important as the next 7600ppmv…

Massively simplified generalisations are never helpful..

No scientist would ever claim that colder temperatures at higher altitudes are a consequence of noise, nor would they be convinced of “the existence of sizzling mountaintop conditions.” That’s patently ridiculous, and a straw-man if ever I saw one.

They would note a number of things about your analogy:
1) Heat heading towards the top of a room is a matter of convection. There is no such thing as the ‘“greenhouse” nature of height’. The greenhouse effect is a completely different effect.
2) A kitchen is insulated at the top by the ceiling and the roof, meaning the heat has a harder time escaping
3) A kitchen doesn’t have seasons, a coriolis effect, a day-night cycle, ocean currents, or large differences in pressure, all of which lead to mixing of the atmosphere.

From this they would probably conclude that the two systems can’t really be compared in a useful way.


Of course I am simplifying…because everybody can go up a mountain and verify for themselves what does happen. Unfortunately nobody can go “up” to, say, CO2 concentrations of 5000ppmv and check what has become of our planet’s temperature, so we can only guess. The one thing we should be really sure of, however, is that an effect measured in the lab does not have necessarily to materialize in the real world.

Laboratories and the real world cannot be compared in a climatologically useful way. That’s why people developed GCMs.

Good analogy.

As M&E state in the book “Taken by Storm”, the atmospheric lapse temperature determines whether CO2 is a warming agent, or a cooling agent.

At 6.5 deg C/1000 meters, or more, its a warming agent.

At 6.0 or less (IRC), its a cooling agent.

Measured is 4 to 10.

The models, of course, all use one parameter, 6.5 deg C/1000 meters.

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