Andrew Dessler rebuts Roy Spencer

Most of the focus at the moment is rightly on the coronavirus. Since I have no relevant expertise whatsoever, all I’ll say is that I hope everyone is doing their best to stay safe, and listening to the advice that’s being given. Instead, I thought I would post this short video by Andrew Dessler, in which he rebuts a recent presentation by Roy Spencer. What I found interesting was how often Roy Spencer would say things that sounded like they were directly supported by the scientific evidence, but were really just his opinion about the significance of the evidence. For example, “there’s no climate crisis”. People are perfectly entitled to believe this, but scientific evidence alone doesn’t determine if something is a crisis, or not; that’s a judgement that we make, based on the evidence available.

Of course, many will claim that this is, or is not, a “climate crisis” without always being clear that this is their judgement/opinion. When it comes to activists, and others who advocate for specific policies, I tend to think that this is fine. They’re obviously presenting their opinions/judgements; I don’t think they need to make this explicit. Scientists, on the other hand, are speaking from a position of authority and really should distinguish between what they can conclude directly from the evidence (adding greenhouse gases to the atmosphere will lead to global warming) and what judgements they might make, given the evidence (it’s a climate crisis).

Enough from me. Andrew’s video rebuttal is below.

This entry was posted in Climate change, Policy, Roy Spencer, The philosophy of science, The scientific method and tagged , , , . Bookmark the permalink.

68 Responses to Andrew Dessler rebuts Roy Spencer

  1. John Hartz says:

    ATTP: Thanks for posting Dressler’s rebuttal video. Do you know if he intends to do more of them?

  2. JH,
    Andrew also had a nice video presentation about climate sensitivity that I discussed in this post.

    He also had a good video about the greenhouse effect

    and one that discusses climate science more generally.

  3. you have relevant experience and knowledge that you can employ with regard to Covid 19. The underlying issues with Covid 19 and the climate crisis are the ways that human beings exist on the planet and the impacts that these ways produce. Step up, think more please.

    physicists can stretch a little, can’t they?

    Think and post about the ways that we have abruptly changed the ways we live in response to Covid 19 when so little similar change had been made as a response to our emissions.

    Think and post about how we might use the abrupt changes happening as a truly grand experiment in how much and how fast we could reduce emissions when we “need” to.

    Think and post about how we might be wise to use this sudden reduction to retool the economic reboot to happen with a smaller emissions bootprint.

    Think and post about how science and science communication might still proceed without large meetings that require a lot of air travel and don’t really allow for the social distance needed to address Covid 19.

    Think and post about how the global economic slowdown will turn into a drop in yoy emission rise and what we might see in terms of temp bump from the accompanying drop in aerosols that damp down the actual current level of temp increase at our current CO2 saturation level.

    Stretch a little and consider a post based on your readings and understandings of outbreaks like the Spanish Flu of 1918 or Covid 19.

    You are smart and should have some time for this work if you are experiencing a little extra time in your daily routine from the social changes required by Covid 19.

    I appreciate your work here. This website is a bit of a bully pulpit. Own that.

    Cheers and stay well,


  4. John Hartz says:

    Mike: Since the beginning of March, a growing number of articles have been published addressing various aspects of the connection between the Coronavirus (COVID-19) and climate change. You can readily access those I have posted links to on the Skeptical Science Facebook page by going to the Skeptical Science website and reviewing the Weekly News Roundups

  5. The more Andrew Dessler speaks via lectures, video, etc., the better off we are all.

    Obviously, his technical arguments and supporting evidence are well-constructed. The climate sensitivity video ATTP links to is an excellent example.

    But there is something about Dessler’s inflections, pacing, sentence structure and surely other things that a communications expert could identify that somehow makes Dessler just a very compelling speaker.

    And I may take some flack for this, but I think some of the more popular climate science communicators are actually rather weak in this regard. As prominent examples, I’ve seen Jim Hanson speak live, I’ve seen Michael Mann speak live, many videos. And I know that they’re popular and the content is impeccable, but I just don’t think that they are particularly strong public speakers. And Dessler himself mentions Richard Alley in the video in the original post, and I grant that Alley is very animated in his talks, but it borders on over-the-top. Even though I find the content awesome and compelling, I find it almost exhausting listening to him, and to someone unfamiliar with the material, I think it can detract from the gravitas/credibility quotient.

    But Dessler seems to hit a very sweet spot with his speaking style. Maybe it is just my personal preference, but I would bet that a communications expert could pinpoint and identify what is resonating with me.

    And I am not knocking anyone in the trenches getting out and engaging with public in visual/spoken form. Far from it. I am just thinking everyone could learn from Dessler or from domain experts in communications.

  6. Holger says:

    Nice rebuttal from A. Dessler!

  7. John Hartz says:

    ATTP: Speaking of future OPs, you’ll find lots of stuff to mine in this article…

    Five tough questions to ask about reaching net zero climate targets, Opinion by Myles Allen, Thomas Hale, Tim Kruger, Stephen Smith & Kaya Axelsson, Voices, The Independent (UK), Mar 14, 2020

  8. small,

    you have relevant experience and knowledge that you can employ with regard to Covid 19.

    I may have the kind of expertise that could be useful if I was working with others who had more directly relevant expertise. However, if I’m not actively collaborating with other experts, then I think I should be cautious as to what I say.

  9. at RNS: Kevin Anderson is also quite compelling as a public speaker imo.
    at ATTP: caution is warranted, but ask questions in your posts and see what expertise lurks with the readership. I don’t have it, but I think there are others here who might.

    And again: abrupt dropoff in emissions and aerosols seem like they would suggest some physics questions. Am I wrong about that?

  10. at JH: I found this at Skeptical Science:

    But not a lot else either there or on the facebook page. Share links here if you can/would please.

  11. Phil says:

    Despite ATTP’s implied ban on COVID-19, I think this radio programme (especially the final segment – an interview with Prof Andrew Cunningham – that begins at 22 mins) is very interesting and rather worrying and deserves a wide audience. It raises some points about zoonotic diseases that touch on Climate Change, human population growth and species extinction as well as Chinese cultural practices.

    BBC Radio 4 The Food Programme

  12. Phil says:

    Oops sorry, theres an extra double quote character in the URL I just posted. Should be:

  13. Phil,
    I wasn’t implying a ban on discussing it (if people think they have relevant information, they’re welcome to post it). I just don’t think I’m in a position to say anything that differs from what is already being presented publicly.

  14. John Hartz says:

    Mike: Sorry, there are way too many articles to list here. As I stated above, go to the SkS website and peruse the most recent Weekly News Roundups that I have posted, They are always posted on Saturday. Here’s the url for the one posted on Sat. Mar 14.

  15. Alberto Zaragoza Comendador says:

    I watched minutes 16:00 to 18:00, which discuss the result from Lewis & Curry 2018 versus the CMIP5 models.

    In this section, Dessler’s only complaint of substance is that Spencer quotes the central ECS estimate from the paper, instead of the confidence interval. Dessler claims that LC18 reports an ECS range of ‘1ºC to 3ºC’. Well, kind of – it’s actually 1.15ºC to 2.7ºC for the Cowtan & Way record and the longest timespan, for a 90% confidence interval.

    Dessler then says the overlap between these confidence intervals is ‘pretty good’. Not sure what is the scientific definition of ‘pretty good’, but Table 5 in LC18 reveals that a value of ECS_hist of 2.89ºC would still be inconsistent with the paper’s results. The value of ECS_hist that the paper calculates for CMIP5 models is indeed just over 2.89ºC, both for median and average; see the paper’s ECStoICS.csv file. Kyle Armour’s 2017 study found almost identical values: 2.87ºC for average ECS_hist, 2.9ºC for median (see Table S1).

    Obviously, if result A is in the border between “consistent with” and “inconsistent with” result B, then the agreement between these two results can’t be very good. Perhaps you could call it a borderline agreement.

    Dessler then says the value in LC18 is ‘almost certainly low-biased’, without citing any evidence. Maybe he mentions this in the other part of the video, but I suppose he’s thinking about the difference between ECS and ECS_hist. The fact that ECS differs from ECS_hist in models is well-known, and discussed in the paper; the difference between these two terms is not nearly big enough to explain the discrepancy between the results from LC18 and those from the CMIP5 models. As explained above, there is a major difference between the result in LC18 and that of the CMIP5 models even if one restricts the comparison to the latter’s ECS_hist values.

    Dessler also says the range of sensitivity in CMIP5 models is 2ºC to 4.5ºC. Not sure where he got the latter number; if one is talking about ECS there are at least two models above 4.5ºC, including at least one above 5ºC (Armour reports two above that mark and one exactly at 5ºC). If one is talking about ECS_hist instead, then the maximum value is either 4ºC (per LC18) or 3.8ºC (per Armour).

    This part of the video is simply a hit job lacking any scientific substance. All one can learn is that – surprise – there is a confidence interval in the LC18 results.

  16. dikranmarsupial says:

    Spencer was cherry picking. This is what you get if you don’t cherry pick. The error bars of “energy balance” models and GCMs do overlap substantially.

  17. Alberto,
    The point is that there is an overlap, so that even the Lewis & Curry type estimates don’t rule out ECS values close to ~3C. Also, there has been a lot of work on potential biases in these energy-balance/observationally-based estimates, some of which I’ve discussed here. In fact, one of Andrew Dessler’s videos that I highlighted in an earlier comment discusses why, for example, the ECS is probably > 2C.

  18. dikranmarsupial says:

    “I watched minutes 16:00 to 18:00” and ignored the “total bullshit” at 13:48? It appears Spencer isn’t the only cherry picker.

  19. verytallguy says:

    “Since I have no relevant expertise whatsoever, all I’ll say is that I hope everyone is doing their best to stay safe, and listening to the advice that’s being given. “


    Not sure you’ve really understood this blogging malarkey 😉

    Best to all, particularly you and yours in the high risk categories.

  20. Very good. My takeaways from Andrew Dessler’s analysis of the talks were: ‘unclear if Spencer still reads the literature’ (ouch); Spencer mixes his value judgments with the science; he misses out a lot of what is known; keeps engaging in ‘fake uncertainty’; is the real real alarmist, claiming the world economy will end if we move to renewables, etc.

    History will not be kind to Spencer, using his scientific position to provide air cover for delayism.

  21. “Not sure you’ve really understood this blogging malarkey”

    That’s why you go to a forum that allows freedom of discussion

  22. Steven Mosher says:

    hey we get to do an experiment with degrowth!

  23. Yes, degrowth experiment underway. We needed to look into that anyway to address emissions problem. Too bad that we are doing the degrowth experiment in a manner that is also going to test our global health care response to pandemic. It is also a great opportunity to choose which industries to support as long term activities on less precarious planet and which ones need to disappear or reconstitute in right size/right manner format.

  24. anoilman says:

    Well… if you wanted to have fun with Cherry Picking you could compare all the results from credible scientists with the results from all the pseudo skeptics. (Exactly why is the former director of environmental science for Peabody Energy considered credible? I dunno..)

  25. anoilman says:

    Oh and if you haven’t seen this video about Corona Virus… give it a watch, its funny;

  26. Everett F Sargent says:

    “hey we get to do an experiment with degrowth!”
    “Yes, degrowth experiment underway.”

    Yeah, no temporal scaling issues (monthly versus decadal or two orders of magnitude faster) at all. /:

    I think I’ll build me a reinforced concrete aeroplane 120X larger (in volume) than the Spruce Goose.

  27. Steven Mosher says:

    “Yes, degrowth experiment underway. We needed to look into that anyway to address emissions problem. ”

    wiping out the wealth required to administer climate social justice is not a plan.

    next up reparations. as with climate some nations will bear more responsibility than others.

    just saying

  28. Willard says:

    GRRRRROWTH is still underway:

    It’s just in the eye of the beholder.

  29. angech says:

    Iver at the RS blog I am seeking information in my own muddle headed way
    Bindidon says:
    angech Do you REALLY think that climate scientists still try to extrapolate TOA out of surface values, like thy did 50 years ago, and produce this out of some simulation?*

    Without Roy’s input into my lack of knowledge I am forced to slowly learn this on my own.
    Thanks for your help.
    I learned a bit more from an article “Andrew Dessler rebuts Roy Spencer” where Mr Dessler puts up some videos on the subject, without really rebutting Roy.

    1. temperature is dependent on height in the atmosphere.
    2. 240W/M 2 is the effective amount of energy absorbed by the earth atmosphere and surface.
    3. The TOA is extrapolated from that surface value just like 50 years ago*
    4. The effective radiating Temp for 240 W/M S is 255C at the TOA.
    As it would be for the surface area with no GHG in the atmosphere.
    This cleared up a lot of confusion for me as I was getting the 2 different values 240/255 confused when discussing energy output v temperature .

    The problem persists though.
    It is one thing to standardize the energy balance diagrams to the earths surface.
    It is another to use the energy estimated at the TOA with the other figures at the earths surface in the energy budget diagram to try to calculate an imagined energy loss.

    I will try again.
    if the effective radiating Temp for 240 W/M S is 255C at the TOA.
    Can you please calculate what it is at the earth’s surface ??
    With SB is it a good guess that it might be the emitted surface radiation, 395 W/M 2.

    Perhaps someone here can fix my broken logic circuits.

  30. Steven Mosher says:

    “Perhaps someone here can fix my broken logic circuits.

    I’m fresh out of miracle glue

  31. angech,
    The 255K simply comes from an energy-balance calculation where you calculate the blackbody temperature of something that would emit the same amount of energy per square metre per second as we get from the Sun. Since the latter is 240 W/m^2 (taking albedo into account) you get

    \sigma T_p^4 = 240 Wm^{-2} \Rightarrow T_p = 255 K.

    You can’t from that, though, calculate what it would be at the surface because that depends on the planetary greenhouse effect. There’s not some simple relationship. If you know the surface flux (395 W/m^2) then you can use that to get the surface temperture (T_s \sim 288K) but there isn’t a simple way to get the surface flux from the TOA flux.

  32. angech says:

    my broken logic circuits.
    “I’m fresh out of miracle glue”
    Thanks anyway.
    Thanks ATTP

  33. Chubbs says:

    I won’t be as diplomatic as Dessler. Spencers’ presentation was horrible, Heartland 101. Interesting that the presentation did not include his own satellite measurements. A very simple comparison (top link), indicates that UAH is missing a lot of warming, particularly after the MSU–AMSU transition in 1998. Starting in 2002, there has been an improvement in satellites (second link), largely eliminating diurnal drift, and UAH6 is spiking.

  34. BBD says:

    LC18’s lower bound of 1.15K for ECS is unphysical as in incompatible with palaeoclimate behaviour. So the methodology reveals a significant low bias and the central estimate must be too low.

    I won’t be as diplomatic as Dessler.

    Bravo. Nor will I. Lukewarmerism is sciencey-sounding crap peddled by the politically motivated. The rightwing governments of the US, UK and Australia are in the process of inflicting a dire mess on their citizens because of the standard rightwing bias against evidence, experts and reality. Lukewarmerism is a tool in this box – part of the minimalisation – denialism approach to inconvenient truths.

    Enough is enough, imo.

  35. BBD: I totally agree. Well said.

  36. Mal Adapted says:

    :BBD++ 8^|!

  37. Mal Adapted says:

    Sorry, my last comment was too much like line noise, even without the accidental ‘:’. I meant to say “I, too, wish to associate myself with BBD‘s comment”, with a grim, tight-lipped face!

  38. I know it’s hard and outside our comfort zone, but I really think we should expand our thinking to encompass the various threats, long and short term, that arise from the way our species chooses to live on the planet. Here’s a good read on that topic:

  39. John Hartz says:

    Yet another example of the anti-science crowd at work…

    On January 30, 2020, the World Health Organization (WHO) declared that the outbreak of novel coronavirus 2019, which causes the disease COVID-19, was officially a “public health emergency of international concern.” At the time, there were cases confirmed in 19 countries and deaths in China had reached 170.

    The very next day, the American Council on Science and Health (ACSH) published an article titled, “Coronavirus in the U.S.: How Bad Will It Be?”

    “Is coronavirus worse than the flu?” it began. “No, not even close.”

    “It already has spread from person-to-person in the U.S., but it probably won’t go far,” ACSH added. “And the American healthcare system is excellent at dealing with this sort of problem.”

    ACSH is one of several organizations promoting climate science denial that are now spreading misinformation on the coronavirus, with potentially deadly consequences.

    Meet the Climate Science Deniers Who Downplayed COVID-19 Risks by Sharon Kelly, DeSmog, Mar 16, 2020

  40. JCH says:

    While the imbeciles mock me Cesspool, Etc., my family has been at around 97% total isolation for 3 weeks. In my spare time, I’ve been working on my USA-COVID-19 quilt. Virtual quilting is fast and easy. Be safe:

  41. Joshua says:

    JCH –

    You never answered my question over there.

  42. I think it makes sense to report ACSH for inaccurate info on their facebook page. Wouldn’t it be great to persuade Facebook to slam their pages shut with a public notice that the authors had provided horrible information?
    click on the three dots next to “create fundraiser” then choose the bottom selection “find support or report page.”

  43. JCH says:

    Joshua – moderated. I’ve read Chinese test results.

  44. Everett F Sargent says:

    Chubbs says:

    “A very simple comparison (top link), indicates that UAH is missing a lot of warming, particularly after the MSU–AMSU transition in 1998.”

    You can fix that one rather easily, for TMT, plot UAH vs RSS, starting in 1999 add ~0.10C to UAH, There is more or less a step increase necessary for UAH of 0.10C circa 1999-present.

    Woy’s equation (TLT=1.538*TMT-0.548*TTP+0.010*TLS) now works for both datasets giving ~0.2C/decade for either.

    “Starting in 2002, there has been an improvement in satellites (second link), largely eliminating diurnal drift, and UAH6 is spiking.”

    I saw that Zou paper myself, just now trying to get NOAA STAR to update their MSU datasets (v3.0 abd v4.1) through to, and including, February.(currently stalled at December of last year).

    As to UAH spiking, I agree, now where is Roy’s ‘cubic fit for illustration purposes’ anyways?

  45. John Hartz says:

    Recommended reading:

    How COVID-19 Is Like Climate Change, Opinion by Ben Santer, Observations, Scientific American, Mar 17, 2020

    As you will discover, COVID-19 is personal for Santer.

  46. Ben McMillan says:

    I’m still thinking the AIRS data is basically “case-closed” on the ‘mystery’ of MSU satellite time-series. There is no disagreement between real satellite measurements of ground temperature and in-situ. MSU (RSS/UAH) is just not very good for surface temperature. So don’t use it…

  47. Everett F Sargent says:

    Ben McMillan,

    Yes, of course.

    But try telling that to UAH and RSS, as both are rather bogus, certainly for TLT as any metric for GMST (or subsections thereof). There are also major issues with even calculating a consistent TMT between groups (heck, NOAA STAR currently has two, v3.0 and v4.1, that don’t agree with each other).

    In other words, people will still choose whichever time series suits their own confirmation biases (right through to peer-reviewed publications), see, for example …
    Has global warming already arrived?

    Monkers was using RSS until the switch overs, v3.3/v4.0 for RSS and v5.6/v6.0 for UAH. Those two switch overs are enough to tell me that both are basically crap (oh and add NOAA STAR to that steaming pile). So we get to play with and argue about crap time series.

  48. John Hartz:
    re: The Ben Santer SciAm paper has got Ryan Maue upset enough that he has called Santer “depraved and soulless”. So I had to respond in kind :

  49. Steven Mosher says:


    Yes AIRS is good

    back in 2014 I showed the same thing

    Silence from Skeptics

  50. David B Benson says:

    Estimating extreme weather events:

    Harder in a warming world.

  51. Willard says:

  52. Ben McMillan says:

    Also, there is a potential link between air pollution and deaths due to diseases like SARS. These viruses affect most severely those whose lungs are in worst shape already.

    Even in the short term, it is plausible that clean air may actually somewhat reduce the disease burden of this disease. It will certainly help with others, and that will keep some people with other diseases out of hospital beds.

    Probably phasing out coal + phasing in electric transport will be largely driven by local pollution impacts rather that global CO2. The health impacts in the ‘short’ term are big compared to typical estimates of climate damages.

  53. Dave_Geologist says:

    Mal, why did you want to redirect BBD to an exclamation mark? 😉

  54. Willard says:

    > Silence from Skeptics

    Good post, Mosh.

  55. JCH says:

    Just for the record, I did not wear a mask when I went grocery shopping. Professor Curry has left that up. Cesspool Etc.

  56. John Hartz says:

    ATTP: Possible fodder for a new OP…

    Verification of extreme event attribution: Using out-of-sample observations to assess changes in probabilities of unprecedented events by Noah S. Diffenbaugh, Science Advances 18 Mar 2020, Vol. 6, no. 12, eaay2368, DOI: 10.1126/sciadv.aay2368

  57. PP
    Ryan Maue may salivate over the pandemic displacing climate change in the news, but Anthony Watts has outdone him with a climate blog alternative medicine breakthough

    WUWT has adduced Schweppes Tonic Water as the next big thing in coronavirus cures:

  58. Just Andrew Dessler being great again. Not too surprising, given his track-record of debunking the sort of things Roy Spencer and John Christy say.

  59. To address Alberto Zaragoza Comendador’s comment above:

    “Dessler then says the value in LC18 is ‘almost certainly low-biased’, without citing any evidence. […] This part of the video is simply a hit job lacking any scientific substance.”

    Andrew Dessler co-authored multiple studies estimating climate sensitivity, including critiquing the energy-budget-model-based estimates of Lewis+Curry. And that’s not even touching on the wealth of other research rebutting Lewis+Curry’s estimates. So Dessler knows what he’s talking about here, even if he doesn’t go into all the technical details in that video. I think it’s best to read the literature, as per the advice Dessler (implicitly) gives Spencer in that video. I’ve cited some of Dessler’s co-authored contributions to that literature below, long with another from him on this topic:

    “Potential problems measuring climate sensitivity from the historical record”
    “The influence of internal variability on Earth’s energy balance framework and implications for estimating climate sensitivity”
    “Estimating transient climate response in a large‐ensemble global climate model simulation”
    “The impact of forcing efficacy on the equilibrium climate sensitivity”
    “An estimate of equilibrium climate sensitivity from interannual variability”

    “climate sensitivity at Univ. of Utah”, from 17:59 :

  60. angech says:

    Andrew Dessler, SM, ATTP.
    “Satellites do not measure temperature”
    “They measure photons”
    “They measure voltage”

    Seriously, How does ATTP know the temperature of stars then?
    We all know they measure temperature.
    Yes they get the measurements from infrared photons etc.
    It is a valid recognised form of temperature measurement.
    And it is data.
    real measured data.

  61. angech,
    Yes, but the point is that none of those measurements are actually temperature. You need some model to convert what is measured into a temperature. For example, for a star you’ll typically measure a spectrum. You can then use that spectrum to determine some kind of temperature. Even then, it’s not necessarily unique. You could fit a blackbody to your spectrum. You could try to determine the peak of the spectrum and then use Wien’s Law. You could try to determine the total luminosity and then convert that into a temperature (which also requires an estimate of the star’s radius). You can even use the spectral lines themselves. These should all give you very similar results, but they probably won’t be exactly the same.

  62. Since folks are discussing satellite-based trends, has anyone been able to check out the paper below? I haven’t been able to access it:

    “A Fundamental Climate Data Record Derived from AMSR-E, MWRI, and AMSR2
    Fundamental climate data records (FCDRs) play a vital role in monitoring climate change. In this article, we develop a spaceborne passive microwave-based FCDR by recalibrating the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) on the Aqua satellite, the microwave radiometer imager (MWRI) onboard the Feng-Yun-3B (FY3B) satellite, and the Advanced Microwave Scanning Radiometer-2 (AMSR2) onboard the JAXA’s Global Change Observation Mission first-Water (GCOM-W1) satellite.”

  63. udoli says:

    Can anybody please give a reference to the “recently published paper” on CMIP6 models which is cited in minute 20 of the video? Thank you

  64. I think he’s referring to this paper, which isn’t CMIP6 specific. It’s just highlighting how well cimate models have done in projecting the observed warming.

  65. udoli says:

    Thank you, but he is evidently speaking about CMIP6 models, which is not the topic of this paper. He must have in mind another paper.

  66. No, I think he is referring to that paper. There can’t yet be a paper that has shown how well CMIP6 models have done because they’ve only just been released. I think he’s referring to climate models in general and is suggesting that given that climate models in general have been shown do well, there is no reason to think that the CMIP6 models will be any different.

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