Back in July, David Evans had on opinion piece in the Australian claiming:

The greenhouse signature is missing. … The signature of an increased greenhouse effect is a hot spot about 10km up in the atmosphere over the tropics.

This is wrong. The hot spot is not the signature, since you get a hot spot, no matter what the cause. The signature is stratospheric cooling combined with tropospheric warming and that has been detected.

Despite being told this, Evans repeated his false claim on ABC radio prompting Barry Brooks to explain again that:

the hotspot was not a signature of the greenhouse effect – it is a signature of warming from any source

Evans just ignored this as Brooks relates:

Unsurprisingly, [Evans] deploys the standard non-greenhouse theorist approach of yet again blithely ignoring any refutation and simply repeating the exactly the same arguments again in a third forum. So, yet again, a climate scientist had to patiently refute this.

So guess what we find on ABC Unleashed on Friday? Evans repeating all the false claims from his earlier pieces. (Though he has cranked up the rhetoric and is now making defamatory statements about climate scientists.) And, of course, he includes this:

The signature of an increased greenhouse effect consists of two features: a hotspot about 10 km up in the atmosphere over the tropics, and a combination of broad stratospheric cooling and broad tropospheric warming.

I suppose we should count our blessings that he deigns to mention the stratospheric cooling thing.

Evans volunteered to defend his piece at Club Troppo. I pressed him on his claims:

The hot spot is not the signature of greenhouse warming. The IPCC report you cite does not say that it is. I quoted the relevant part above. Here it is again:

The observed pattern of tropospheric warming and stratospheric cooling is very likely due to the influence of anthropogenic forcing, particularly greenhouse gases and stratospheric ozone depletion.

His response

Now Tim, look at the sentence after the one you quoted: “The combination of a warming troposphere and a cooling stratosphere has likely led to an increase in the height of the tropopause.” That increase in the height of the tropopause IS the hotspot! The hotspot arises in AGW theory because an increase in greenhouse gases (of CO2 due to humans, and of water vapor due to increasing temperature) pushes the top of the tropopause higher, thus replacing cold stratosphere with warmer troposphere at the top of the troposphere — which is at about 10km over the tropics. (Btw, it now appears that the atmosphere just drops out water vapor as it is replaced by CO2, to keep the total greenhouse effect about constant. This is the nub of the argument, and where AGW went wrong.)

Despite going on endlessly about the hot spot for a half a year, Evans doesn’t even know what it is. The hot spot is not an increase in the height of the tropopause. You’d get that from uniform heating of the troposphere as well. The hot spot is a decrease in the lapse rate, as the team at RealClimate explains:

[The hot spot] really has nothing to do with greenhouse gas changes, but is a more fundamental response to warming (however caused). Indeed, there is a clear physical reason why this is the case – the increase in water vapour as surface air temperature rises causes a change in the moist-adiabatic lapse rate (the decrease of temperature with height) such that the surface to mid-tropospheric gradient decreases with increasing temperature (i.e. it warms faster aloft). This is something seen in many observations and over many timescales, and is not something unique to climate models.

And increasing CO2 does not decrease water vapour. See, for example Dessler, A. E., Z. Zhang, and P. Yang (2008), Water-vapor climate feedback inferred from climate fluctuations, 2003-2008, Geophys. Res. Lett., 35:

Warming temperatures evaporate water, increasing humidity. This increase in humidity has the potential to further warm the atmosphere because water vapor is a potent greenhouse gas. This water vapor feedback has the capacity to about double the direct warming from greenhouse gas increases. Using satellite data, Dessler et al. (2008) observed and quantified the behavior of atmospheric water vapor and the water vapor feedback during variations of the Earth’s climate between 2003 and 2008. They found that global averaged surface air temperatures on Earth varied by 0.6°C during the years analyzed, with specific humidity over most of the troposphere increasing with rising global surface temperature averages. Relative humidity increased in some regions and decreased in others, with the global average remaining nearly constant at most altitudes. The water vapor feedback implied by these observations is strongly positive, similar to that seen by climate models. The magnitude of the feedback is similar to that obtained if the atmosphere maintained constant relative humidity everywhere.

Update: See also Chris Colose’s post on Evans’ confusion. And Evans sticks his foot deeper into his mouth:

I understand that the water vapor treatment of the models used to be simply to assume constant relative humidity. So in the models, as temperature rose there was more water vapor. Water vapor is a greenhouse gas, so creates a hotpot. (Which is why those models show a hotpot for any source of warming, and why a hotspot is so associated with an enhanced greenhouse effect.) However observations show that since the 1940s the relative humidity has been steadily dropping, pretty much everywhere as I recall (sorry, do not recall link).

Not only does Evans not know what the hot spot is, he doesn’t know what causes it. More water vapour means that there is more condensation up in the atmosphere. Condensation releases latent heat. That latent heat creates the hot spot. And notice the way he counters a link to a peer-reviewed paper that shows that relative humidity stays the same as the planet warms, with a “do not recall link” cite.

Comments

  1. #1 dhogaza
    December 20, 2008

    This would be hilarious if there wasn’t so much riding on the issue …

  2. #2 Barry Brook
    December 20, 2008

    Evans: “Btw, it now appears that the atmosphere just drops out water vapor as it is replaced by CO2, to keep the total greenhouse effect about constant”

    Decoding: “…it now appears… actually means “…according to the contrarian theory I just pulled from my rear orifice…”

    As Tim rightly notes, the latest data [18 Nov 2008] quite clearly show that atmospheric water vapour is increasing as CO2 builds, so “it now appears” that Evans is once again completely back-to-front wrong.

  3. #3 DeanL
    December 20, 2008

    I find it strange that the anti-AGW faith are so ready to accuse climate scientists of creating an issue for their own financial benefit and yet, they don’t apply the same logic to question the motives of those on “their side” of the debate. If I were wanting to use the issue to further my financial status or to gain notoriety, it would be the anti-AGW side that I’d be choosing!

  4. #4 Chris O'Neill
    December 20, 2008

    Despite going on endlessly about the hot spot for a half a year, Evans doesn’t even know what it is.

    A clear demonstration of the cognitive failure caused by denial. He won’t make one iota of mental effort to understand something that might contradict his view.

    BTW, Evans:

    That increase in the height of the tropopause IS the hotspot! The hotspot arises in AGW theory because an increase in greenhouse gases (of CO2 due to humans, and of water vapor due to increasing temperature) pushes the top of the tropopause higher, thus replacing cold stratosphere with warmer troposphere at the top of the troposphere

    If Evans knew anything about what he was saying and applied some thought to it then he might realize that increasing the height of the tropopause replaces air that warms as you get higher in the stratosphere with air that cools as you get higher in the troposphere, i.e. the replaced air is actually cooler than otherwise. Yet another example of cognitive failure by Evans.

  5. #5 Chris Colose
    December 20, 2008

    Tim,

    I have a follow up to this post and your discussion with David Evans, here
    http://chriscolose.wordpress.com/2008/12/20/skepticsdenialists-part-2-hotspots-and-repetition/

  6. #6 Arthur Smith
    December 20, 2008

    Interesting – of course this stuff doesn’t originate in Australia – the hot spot featured heavily in Monckton’s ravings this summer, and the realclimate discussion was triggered by earlier denialist rantinga on the subject. Lucia at rankeploits has a whole confused post up on it right now which I’ll need to check up on again once I’m not so busy from the weekend.

  7. #7 Barton Paul Levenson
    December 21, 2008

    Evans’s mention of water vapor “dropping out” as CO2 rises is probably a reference to Ferencz Miskolczi’s crackpot theory that the atmosphere works to keep gray infrared optical thickness fixed at τ = 1.87. In reality, of course, this would contradict the Clausius-Clapeyron law, at least superficially. But as someone pointed out above, water vapor is rising as CO2 rises, not declining. (The link didn’t work, by the way.)

  8. #8 Barry Brook
    December 21, 2008

    Here is that link again – it is a Science Daily article which covers the Dessler et al paper Tim mentioned:

    http://www.sciencedaily.com/releases/2008/11/081117193013.htm

  9. #9 Jarrah
    December 21, 2008

    Rex has very gently torn Evans apart on that thread. Tellingly, Evans has ignored him so far.

  10. #10 Boris
    December 21, 2008

    Nothing confuses skeptics more than this issue, which makes it a sort of canary in the coal mine for someone’s qualifications. Canaries: yet another victim of global warming.

  11. #11 John Mashey
    December 21, 2008

    As per my anti-science reasons, and from past consideration of “rocket-scientists” at DeSmogBlog,
    I’d conjecture the reasons PSYCH-1 and PSYCH-3, i.e., likes publicity, low-bar to be a contrarian. Others may apply.

    Hence, no surprise.

  12. #12 Hot & Bothered
    December 21, 2008

    This stuff is now on the IPA’s website – http://jennifermarohasy.com/blog/2008/12/trading-carbon-as-a-belief/ .

    The requests for peer review winds them up.

  13. #13 Hot & Bothered
    December 21, 2008

    This stuff is now on the IPA’s website – http://jennifermarohasy.com/blog/2008/12/trading-carbon-as-a-belief/ .

    The requests for peer review winds them up.

  14. #14 Hot & Bothered
    December 21, 2008

    This stuff is now on the IPA’s website – http://jennifermarohasy.com/blog/2008/12/trading-carbon-as-a-belief/ .

    The requests for peer review winds them up.

  15. #15 Hot & Bothered
    December 21, 2008

    This stuff is now on the IPA’s website – http://jennifermarohasy.com/blog/2008/12/trading-carbon-as-a-belief/ .

    The requests for peer review winds them up.

  16. #16 Tim Lambert
    December 21, 2008

    **Update:** See also [Chris Colose's post on Evans' confusion](http://chriscolose.wordpress.com/2008/12/20/skepticsdenialists-part-2-hotspots-and-repetition/). And Evans [sticks his foot deeper into his mouth](http://clubtroppo.com.au/2008/12/19/david-evans-greenhouse-sceptic-debates-his-views-on-troppo/#comment-338006):

    >I understand that the water vapor treatment of the models used to be simply to assume constant relative humidity. So in the models, as temperature rose there was more water vapor. Water vapor is a greenhouse gas, so creates a hotpot. (Which is why those models show a hotpot for any source of warming, and why a hotspot is so associated with an enhanced greenhouse effect.) However observations show that since the 1940s the relative humidity has been steadily dropping, pretty much everywhere as I recall (sorry, do not recall link).

    Not only does Evans not know what the hot spot is, he doesn’t know what causes it. More water vapour means that there is more condensation up in the atmosphere. Condensation releases latent heat. That latent heat creates the hot spot. And notice the way he counters a link to a peer-reviewed paper that shows that relative humidity stays the same as the planet warms, with a “do not recall link” cite.

  17. #17 Chris O'Neill
    December 21, 2008

    And notice the way he counters a link to a peer-reviewed paper that shows that relative humidity stays the same as the planet warms, with a “do not recall link” cite.

    He’s not worried about looking like an idiot.

  18. #18 Bernard J.
    December 22, 2008

    Sanity alert!

    H&B’s link at #12 to Marohasy’s thread will pull the unwary into a number stereotypical Bird rants. In the past they used to be amusing, then they were bemusing, but now the gibberings of the man are just alarming and slightly disgusting.

    Be warned!

  19. #19 Tim Lambert
    December 22, 2008

    Oh my. [More David Evans](http://clubtroppo.com.au/2008/12/19/david-evans-greenhouse-sceptic-debates-his-views-on-troppo/#comment-338043)

    >Satellites use microwave sounding to measure temperature, which only works on the lower five kilometers of the atmosphere. That is, satellites cannot measure temperatures above 5 km up in the atmosphere. …

    >I didn’t intend it to say anything about radiosondes, and I think it is unfair to read it that way (but if you didn’t know about the 5km height thing, it’s understandable).

  20. #20 Nexus 6
    December 22, 2008

    No wonder he’s done a runner – that one’s a shocker, even compared to all the other errors picked apart in comments.

    Evans won’t be back, me thinks.

    I did start preparing a post on all the other errors and falsehoods in his screed, but I’ve only got a 6-pack of ale in the fridge. Too much fluff. Not enough beers. Of well.

  21. #21 TrueSceptic
    December 22, 2008

    15 Bernard,

    Bird Anthology here http://notahedgehog.wordpress.com/2008/08/26/speaking-of-irony/

    He’s now found his way over to the JREF forums. He realises he can’t use the same language there, but is much the same otherwise. See http://forums.randi.org/showpost.php?p=4275639&postcount=38 and http://forums.randi.org/showpost.php?p=4275654&postcount=683

  22. #22 ChrisC
    December 22, 2008

    Deary me.

    AMSU measures both tropospheric and stratospheric temperatures by use of multiple channels. According to NOAA, who run the bloody thing:

    “AMSU-A is a cross-track, line-scanned instrument designed to measure scene radiances in 15 discrete frequency channels which permit the calculation of the vertical temperature profile from about 3 millibars (45 km) pressure height to the Earth’s surface”

    Evan’s knows not what he’s talking about.

  23. #23 Chris O'Neill
    December 22, 2008

    Evan’s knows not what he’s talking about.

    Careful ChrisC, you might get censored.

  24. #24 JB
    December 23, 2008

    Arthur Smith says

    the hot spot featured heavily in Monckton’s ravings this summer, and the realclimate discussion was triggered by earlier denialist rantinga on the subject. Lucia at rankeploits has a whole confused post up on it right now.”

    The so-called “confusion” is not so much “confusion” as it is failure to know the meaning of a word — and laziness, since it’s so easy to look up. The “confusion” arises because some people simply do not know what the word “signature” means (some also do not know “fingerprint” means).

    With financial transactions (and legal matters), a “signature” is a sign that identifies a single person with high probability. A fingerprint, with even higher probability: essentially, a uniquely identifying sign.

    The reason signatures and fingerprints are used is precisely because it is unlikely that two people will have the same signature — even less likely that they will have the same fingerprint.

    So when one sees a certain signature (or fingerprint), one can be very confident that one has seen evidence of that person and that person alone.

    Scientists use the term in the same way.

    Those who are confused about the meaning of signature (and fingerprint) seem to be using the term as if it meant merely “one characteristic” of something that could be shared with multiple things (or people). This is not the way the term signature (and fingerprint) is used by scientists, lawyers, bankers or even by the average person.

  25. #25 Michael
    December 23, 2008

    Thanks H&B, I hadn’t visited the weird world of Jen for a while.

    My favourite was a non-Birdism – the guy who said that he knew, as a child (50 yrs ago), that Einstein was wrong on matters of space and time.

    If only these geniuses would publish, but they are ust too iconoclastic for academia. The world is poorer……

  26. #26 guthrie
    December 23, 2008

    I am amazed that Arthir has put up with Lucia so long. I vaguely recall when she dived into the climate pond, already predisposed to denialism, but it is clear that since climatology refuses to roll over and do as she wants, she has to destroy it by any means necessary.

  27. #27 Bernard J.
    December 27, 2008

    Tim Lambert has similarly acknowledged Arthur Smith’s patience, and I feel compelled to add a hat-tip to Joel Shore and especially to Boris for their attempts to nail Lucia’s floating definitions of ‘signature’ and ‘fingerprint’.

    I am half-expecting the definition for ‘unique’ to similarly acquire contextual permutatons according to denialist fuzzy logic.

    As a tangential aside, I once heard a bit of mathematical humour that included a reference to something along the lines of “approaches zero for very small values of one” – if anyone had a clearer knowledge of the joke I’d be pleased to hear it!

  28. #28 Boris
    December 27, 2008

    I admit I have no patience.

  29. #29 Dano
    December 27, 2008

    I too tire of the same old game of whack-a-mole. Can’t the mole just grow silent from the repeated concussions and be done with it?

    Best,

    D

  30. #30 frankis
    December 27, 2008

    “approaches zero for very small values of one”

    I think Bernard that [anything at all] “… for sufficiently small values of one” goes close enough for jokemaking purposes almost everywhere.

    Thanks for reminding us!

  31. #31 Bernard J.
    December 27, 2008

    Frankis.

    That sounds closer to whatever it was that I’d chortled at years ago. Thanks for clarifying the wording.

    However it might be phrased, what does it say about some of the denialist slippery-science, that I am reminded of this joke when I read their efforts?

  32. #32 Bernard J.
    December 28, 2008

    Boris.

    Your lack of patience on Lucia’s thread does not show. Your humour though, does…

    When Andrew said at Comment #7749:

    We denialists haven’t been shown any evidence that proves AGW

    your reply at Comment #7751:

    Neither have I. Proof is only important in mathematics and liquor.

    had me in chuckling. Andrew’s subsequent response left me less than amused however.

    Interesting. I take this as an admission that your position (a belief in AGW) is a religious one?

    It seems that some denialists rely on a very twisted definition of how science operates, and on fallacious logical inductions, in order to attempt to present a case. I had my third whinge in as many weeks about it at this post (and was promptly followed by more of the same twisted defining and induction).

    Interestingly, after the days and days of semantic nit-picking, Lucia says this on a newer thread:

    The average of the model runs that include volcanic eruptions is definitely not linear.
    Bob and Jason: Whether or not the models agree with the observations depends on your definition of agree.

    (Comment #7746)

  33. #33 Dano
    December 28, 2008

    It seems that some denialists rely on a very twisted definition of how science operates, and on fallacious logical inductions, in order to attempt to present a case.

    They are trying to make sense of the world thru the lens of their worldview. Just because their worldview doesn’t eschew logical fallacy, projection, fear, contrascience and contrafacts doesn’t make them less human.

    Less useful for science-based policy discussion, direction, living, and action, sure.

    Best,

    D

  34. #34 TrueSceptic
    December 28, 2008

    29 Bernard,

    Lucia’s thread on this has really exposed the delusionals, hasn’t it? Did you see the post by Willis Eschenbach?

    >Having said that, since none of the models include thunderstorms, I would not be surprised if the models show the same results for all forcings. Thunderstorms route rising air and energy around the troposphere, by shielding it from any interaction (either by radiation or by mixing) with much of the troposphere. The lack of any representation of thunderstorms in the models is the gaping hole, the giant problem, the elephant in the room that none of the modelers want to talk about.

    >As a result, all the models can possibly tell us is what would happen in a world without thunderstorms … interesting, but hardly applicable to our world. It also makes it totally meaningless to me whether the models show the same result from all forcings.

  35. #35 Dano
    December 28, 2008

    That’s poor, arrogant Willis believing in the infrared iris. Use him for entertainment & don’t take him seriously. Engineer living in Wingnuttia.

    Willis actually argued with me for an extended period that agronomists were wrong about food production because he plotted a trendline and agronomists didn’t, and aren’t agronomists dumb?

    Best,

    D

  36. #36 David Irving (no relation)
    December 29, 2008

    Bernard J – the version of the joke about “sufficiently small values of one” that I’m most familiar with is “1 + 1 = 1 (for sufficiently small values of 1)”. Numerical analysts will be identifiable by their laughter. (It’s all about rounding error.)

  37. #37 Bernard J.
    December 29, 2008

    All of the references to ‘sufficiently small’ finally led me to Wiki via Google, and I had to chortle at the brief summary there. I especially appreciate the humour based upon rounding, having tried to educate countless undergraduates in matters of significant places.

    Well, maybe not ‘countless’ – that would be tantamount to ignoring the actual matter of significant places!

    And if one is seeking something with somewhat more depth, then it wouldn’t hurt to have a look here.

  38. #38 John Philip
    December 29, 2008

    A variation is 2+2=5 for sufficiently large values of 2.

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