Define “AGW”

Spread over the Cook et al 2018 paper are the terms “anthropogenic climate change” and “anthropogenic global warming”. It is also mentioned a in table S2 of the supplementary material. I assume that “anthropogenic global warming” means that global temperatures are rising and humans have an impact. This seems to be supported by the consensus claim from the paper (my emphasis):

There is an overwhelming scientific consensus that humans are causing global warming (Cook et al 2016), with a number of studies converging on 97% agreement among publishing climate scientists or relevant climate papers (Doran and Zimmerman 2009, Anderegg et al 2010, Cook et al 2013, Carlton et al 2015).

That is a far cry from the previous statement in the Alice in Wonderland paper. In that paper, the claim was made that there is a consensus that global warming “presents a global problem”. A claim that obviously was unsupported by the papers that were referenced.

At least he skipped the “dangerous” part of the claim. It is now in line with what the referenced papers researched. As explained in the link above, the referenced papers investigated the claim that global temperatures are rising and that humans have an influence in this. Not whether it is dangerous. Not whether something should be done about it.

However, I don’t think that the term “AGW” is used in this way in the paper. This sentence in the abstract makes me think that he means something different (my emphasis):

Misinformation can have significant societal consequences. For example, misinformation about climate change has confused the public and stalled support for mitigation policies.

This is not something surprising, I read similar claims in Cook’s previous papers. But this statement gives away that it is not just an objective observation that global temperatures are increasing and humans have something to do with it. This is going one step further, it assumes global temperatures are increasing because of humans AND is dangerous enough to support mitigation policies. More, it not only assumes that the effects will be negative, but also that the mitigation policies are able to decrease (or even reverse) these effects.

It is my impression that what is actually meant by “AGW” is more likely some gradation of CAGW (Catastrophic Anthropogenic Global Warming).

This makes the use of the undefined term “AGW” confusing. For example, when the authors claim that they are “refuting AGW”, do they mean they are refuting the claims that temperatures are not going up? Or do they refute the claims that increasing temperatures are not dangerous. If it is the former, then I could agree. If it is the former, I don’t know (there will be winners and losers).

In the same line: who are in fact those “denialists” who are central to this paper? Those who don’t believe in AGW? That would be a rather small list. Or those who don’t believe in the catastrophic aspect of AGW? That could be a large list.

It will also have consequences for the items in the S2 table of the supplementary data. For example, the first item in the table starts with following premise:

P1: There is no observed evidence for AGW.

Do they mean that “there is no observed evidence for a global temperature increase”? Or do they mean that “there is no observed evidence that those global temperatures will be dangerous”? Which are two different propositions. I would reject the first one (depending on the chosen time frame), but could lean towards the second one (dangerous compared to when or to whom?).

By the way, it is not only the term “AGW” that is not defined, the same could be said of the term “cause”. Do they mean that humans are “the only cause” of the warming? Or “the main cause” of the warming? Or cause “most” of the warming? Or “some” of the warming? Or just “any” warming?

Concluding, to me it is not really clear what the definition of “AGW” in the Cook et al paper is. That term is open to multiple interpretations and therefor could lead to a very confusing read: without a clear definition, it means whatever the reader thinks it means.


7 thoughts on “Define “AGW”

  1. vuurklip

    Definition AGW: It’s hot. It’s getting hotter. It’s your fault. It has to be stopped. Send money for more scary “research” papers. (Oh, don’t forget, it’s going to be catastrophic).


    1. trustyetverify Post author

      That reminds me of the news yesterday. An American researcher found micro-particles of plastic in bottled water. A Flemish “eco-toxicologist” (who also does research on micro-plastics) explained to the journalist that the particles most likely came from the plastic screw bottle caps.

      On the question whether we will get sick of it over time, the answer was that they didn’t know, so it is something that we should at least be worried about.

      On the question whether we should still be drinking bottled water, the answer was that he couldn’t confirm that and that he didn’t want to sound the alarm, but we should be concerned about it.

      I am pretty sure that, with such an explanation, this guy will have no problem whatsoever getting funds for this type of studies in the future…


  2. Don132

    trustyetverify, have you notice that there is no experimental proof that CO2 actually does what we claim it does? We say that it back-radiates and thereby warms a surface, but to the best of my knowledge this has never been proved. How could we prove it? How about we put CO2 in an enclosed glass column and measure how it changes the temperature profile of the column compared to an atmosphere without CO2, thereby proving that back radiation will heat the lower atmosphere?

    Nahle has replicated Wood’s 1909 experiment and the gist of it is: CO2 back-radiation does not warm a surface. This is the only actual test of the “back-radiation” mechanism that I know of.

    I think the very large elephant in the room is that the actual mechanism for CO2 warming has never been experimentally proved, and the claims that we can’t do the experiment are pure, utter, and complete hogwash. We are somehow assuming that the experiment must be done within earth’s complete atmosphere and can’t be scaled down.


    1. trustyetverify Post author

      No, I didn’t notice that. It is not a subject that I would look into. I can’t look into everything, so at some point I need to trust. The physics of the greenhouse gas is one (of the countless) examples of such a point.

      I have no problem with the greenhouse effect and I start from the assumption that it exists. It doesn’t prevent me from doing what I want to do in this blog and trying to prove (or disprove) it would mean spending quite some time to catch up with the physics, which is not an option for me, nor interest wise nor time wise nor background wise.

      Not sure however what the linked paper wants to prove. If I understood it correctly, it is an experiment about the warming effect in a real greenhouse and the conclusion is that the warming inside a real greenhouse is the result of convective heat transfer, rather than trapping longwave infrared radiation

      Although I think that is correct (as far as I know, the warming of a real greenhouse is indeed the result of reduction of convection, which is found by Wood and replicated by Nahle), I am not really sure whether this experiment correctly represents what is being called the “greenhouse effect” on Earth. Proving that the warming in a real greenhouse is not the result of trapping longwave infrared radiation, doesn’t necessarily disprove what is called the “greenhouse effect” on Earth. It is not because it has a similar name that it necessarily works by the same mechanism. I am also not really sure whether a cardboard box of 30x30x20 cm covered with a piece of glass (or plastic) is a correct representation of Earth and the complexity of its atmosphere.

      Anyway, this is off-topic for this blog. Its topic is climate (and energy) communication, not proving whether the underlying physics of the greenhouse effect is correct or not.


      1. Don132

        Appreciate your reply. However, this is an important topic and not too hard to grasp. Note that the mechanism for the greenhouse effect must involve the “trapping” of LWIR (longwave infrared): that is the postulated mechanism, is it not? How else could CO2 be warming the surface if not through some sort of back-radiation or trapping or radiative transfer? Yet Nahle has shown quite conclusively that this doesn’t exist.

        Regarding water vapor and the greenhouse effect, no one is arguing that water vapor has no effect on the temperature profile of the atmosphere but it seems that the argument that it back-radiates and that’s why the earth is 33K above the blackbody is wrong. The “greenhouse” effect can be accounting for by atmospheric pressure, which must necessarily shunt the warmth of the atmosphere toward the surface, which is exactly what the “greenhouse effect” is supposed to do. If this seems incredible, remember that there is 14.7psi of atmospheric pressure at the surface, which translates into an astonishing 19,000 pounds/square yard; the reason we don’t feel this is exactly the same reason a deep-sea fish doesn’t feel the pressure, and just swims: the pressure is equalized.

        But more importantly I think we should all notice that there is not one single experiment that proves that the alleged mechanism for CO2 warming exists. The common refrain is that we’re doing the experiment now, on the entire planet, but this is ridiculous. Since when have we not been able to test a molecular mechanism in a laboratory? All it would take would be a sufficiently tall column of atmosphere that controlled for everything except for CO2 content, and then a measurement of variations in temperature profile caused by CO2. No?

        Everything I’m saying is part of a huge controversy that is now taking place among those who are skeptical of climate science but who disagree on what the greenhouse effect is; published papers on this have created quite a buzz, with some dismissing the findings and others realizing that they illuminate a new understanding of how the atmosphere works.

        I thought you might be interested. I certainly won’t press the point if you’re not.


  3. poitsplace

    The problem is far worse than the simple definition of AGW. While such things are a common issue, they are far worse these days in people on the left. Its this inoculation techniques they’ve slowly been developing that turned the whole movement into something that…well it might just as well be a full blown religion.

    Because of their inadvertent self-inoculation, they give their own definitions the most generous interpretation and gloss over substantial problems as if the problems were insignificant (often simply moving on to another problem “Well even if global warming wasn’t happening as stated…there’s ocean acidification…and even if that was wrong the oil will run out soon…and even if…” So for them, AGW is a sort of universal “anthropogenic” signal that needs no explanating. They “know” that climate change “is happening now” and therefore “all weather is now ’caused’ by climate change”. So AGW is literally whatever it needs to be for their green religion …that they don’t realize has become their religion.

    On the other hand, they don’t really even listen significantly to anyone opposing them on any of the related subjects. They simply listen for key words and vomit out whatever learned “inoculation” argument relates to those key words, even if it’s clearly not what you were talking about. They never think for themselves, instead demanding that instead of looking at data that you produce a peer reviewed study from an alarmist approved scientist…which is basically like saying “I’ll only believe I’m wrong if you can show me a study that shows I’m right”



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