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David Evans' Understanding of the Climate Goes Cold

Posted on 15 April 2011 by dana1981

Computer modeler David Evans has written an opinion article published in the Financial Post which has apparently been spread throughout the "skeptic" blogosphere.  Numerous readers have asked that Skeptical Science respond to this article, and we aim to please.

The article contains a lot of empty rhetoric about "the carbon gravy train," "alarmists," and governments' "tame climate scientists."  There are a whole lot of words in the article devoted to not saying very much.  We'll stick to our usual policy and ignore the fluff, focusing on what little scientific content the article contains.

Climate Sensitivity

 About seven paragraphs in, Evans finally gets to his main point:

"This is the core idea of every official climate model: For each bit of warming due to carbon dioxide, they claim it ends up causing three bits of warming due to the extra moist air. The climate models amplify the carbon dioxide warming by a factor of three — so two-thirds of their projected warming is due to extra moist air (and other factors); only one-third is due to extra carbon dioxide."

There is some truth in this paragraph.  We know from fundamental physics that the average global surface temperature will warm approximately 1.2°C from the increased greenhouse effect if the amount of carbon dioxide (CO2) in the atmosphere doubles.  But there are feedbacks which respond to this warming and  either dampen or amplify it, resulting overall in a best estimate of a total of 3°C surface warming if CO2 doubles.  So approximately one-third of the warming is from CO2 alone, and two-thirds from feedbacks, as Evans states.

However, the main error Evans makes here is to claim that climate sensitivity is simply a number churned out by climate models.  In reality, climate scientists have used many different lines of evidence to create numerous independent estimates of the planet's climate sensitivity.  These include not just climate models, but also empirical observational data (Figure 1 and Figure 2).


Figure 1: IPCC climate sensitivity estimates from observational evidence and climate models

Various estimates of climate sensitivity

Figure 2: Various estimates of climate sensitivity (Knutti and Hegerl 2008)

As these figures show, estimates from both models and observational data consistently find that the most likely climate sensitivity value is approximately 3°C for a doubling of CO2.

The Infamous Misunderstood Hot Spot

Evans follows up his misunderstanding of climate sensitivity estimates by demonstrating an extreme degree of confusion about the tropical troposphere "hot spot":

"The climate models all predict that as the planet warms, a hot spot of moist air will develop over the tropics about 10 kilometres up, as the layer of moist air expands upwards into the cool dry air above. During the warming of the late 1970s, ’80s and ’90s, the weather balloons found no hot spot. None at all. Not even a small one. This evidence proves that the climate models are fundamentally flawed, that they greatly overestimate the temperature increases due to carbon dioxide."

Where to begin?  First of all, the 'hot spot' is a predicted consequence of any surface warming, regardless of the cause, based on fundamental atmospheric physics (as we have previously explained).  It's true that climate models predict the 'hot spot' will form, because models are based on that fundamental atmospheric physics.  So ultimately Evans' beef is not with climate models, but with the physics of the moist adiabatic lapse rate (i.e. see Bengtsson and Hodges [2006]).

Secondly, fundamental physics also tells us that water vapor will be a positive feedback, increasing in response to warming according to the Clausius-Clapeyron relation.  Indeed, numerous recent studies using empirical observational data have confirmed the positive water vapor feedback.  For example, Dessler et al. (2008):

"Height-resolved measurements of specific humidity (q) and relative humidity (RH) are obtained from NASA's satellite-borne Atmospheric Infrared Sounder (AIRS)...The water-vapor feedback implied by these observations is strongly positive, with an average magnitude of λ q = 2.04 W/m2/K, similar to that simulated by climate models."

There is also a significant amount of evidence that the 'hot spot' exists.  This remains an unresolved question, because the radiosonde data from the weather balloons Evans focuses on exclusively is not ideal.  Weather balloons were not designed to measure long-term climate changes, especially in moisture.  However, other measurements do indicate the presence of a 'hot spot' in the tropical troposphere.  More research on the issue is needed, but it is incorrect to say there is no evidence for a 'hot spot'.  "Skeptics" normally overstate uncertainty, but ironically in this case, Evans dramatically overstates certainty.

The adiabatic lapse rate also acts as a negative feedback by moving heat higher up into the atmosphere where it can more easily escape, which also serves to cool the surface.  By arguing the 'hot spot' doesn't exist, Evans is contradicting his previous claims about negative feedbacks and low climate sensitivity.

Back in 2008, Chris Colose documented and explained Evans' confusion about the 'hot spot,' and suggested, "How Evans continues to go about this “hotspot” issue should be very revealing."  I think we have our answer.  Evans has not learned from his mistakes, instead choosing to misinform others by propagating his errors to a much wider, and sadly all too receptive audience.

Runaway Warming

Evans continues demonstrating his misunderstanding of basic climate science with a reference to runaway global warming:

"There are now several independent pieces of evidence showing that the earth responds to the warming due to extra carbon dioxide by dampening the warming. Every long-lived natural system behaves this way, counteracting any disturbance. Otherwise the system would be unstable."

Evans of course provides no evidence for his proclaimed warming dampening (a.k.a. negative feedback and low climate sensitivity).  However, his claim that the climate system would be "unstable" otherwise is simply untrue.  Each feedback accounts for a limited amount of energy and additional warming, and thus positive feedbacks will not necessarily lead to an unstable system with runaway warming.

Model Accuracy

Evans proceeds to throw in an false statement about the accuracy of climate models:

"It is no surprise that their predictions of planetary temperature made in 1988 to the U.S. Congress, and again in 1990, 1995, and 2001, have all proved much higher than reality."

Evans apparently refers to the projections made by James Hansen in 1988, and the IPCC reports.  In both cases, the projections have proven remarkably accurate.

Observed global temperatures since 1980 compared to IPCC AR4 model projections

Figure 3: Observed global temperatures since 1980 compared to IPCC AR4 model projections for the business-as-usual A1B scenario. (Source: RealClimate)

In fact as we have previously shown, James Hansen's 1988 projections are consistent with a climate sensitivity of approximately 3.4°C for a doubling of atmospheric CO2, which of course contradicts Evans' principle claim that climate sensitivity is low.

Urban Heat Islands

Although he doesn't actually come out and say it, Evans suggests that the global warming trend in the surface temperature record is an artifact caused by the urban heat island (UHI) effect:

"The official thermometers are often located in the warm exhaust of air conditioning outlets, over hot tarmac at airports where they get blasts of hot air from jet engines, at waste-water plants where they get warmth from decomposing sewage, or in hot cities choked with cars and buildings. Global warming is measured in 10ths of a degree, so any extra heating nudge is important."

The "temperature record is unreliable" myth is another one which has been debunked in our database.  Rural stations show the same trend as urban stations, "good" stations the same trend as "bad" stations, and satellites the same trend as surface stations.  Menne (2010) addressed this concern and found a slight cool bias in poorly-sited stations.


Evans proceeds to commit the common error of cherrypicking short-term temperature changes.

"The satellites say the hottest recent year was 1998, and that since 2001 the global temperature has levelled off."

Even in the satellites, which do not cover the poles (where warming is greatest), 2010 was statistically tied with 1998 as the hottest year on record.  This despite the fact that 1998 had one of the strongest El Niño events in a century, and the effects of El Niño are amplified in the satellite temperature record.  Further, although the timeframes are too short to be statistically meaningful, the satellite trends since 1998 and 2001 are both positive, and the planet continues to warm:


Evans then wonders:

"Why does official science track only the surface thermometer results and not mention the satellite results?"

This would be a good question, if it were remotely true.  In reality, "official science" pays very close attention to satellite temperatures.  For example, they're discussed in great detail in the IPCC report and highlighted every single month by NOAA.

Natural Recovery

Evans then attempts to claim we're just recovering from the Little Ice Age (LIA):

"The Earth has been in a warming trend since the depth of the Little Ice Age around 1680. Human emissions of carbon dioxide were negligible before 1850 and have nearly all come after the Second World War, so human carbon dioxide cannot possibly have caused the trend."

Firstly, almost all of the warming since 1680 has occurred over the past 100 years.  Secondly, the planet doesn't just warm and cool magically.  There has to be a physical mechanism causing every temperature change, and the factors which causd the LIA cooling are not causing the current warming.  The physical evidence clearly shows that carbon dioxide is causing the current warming trend.


Evans continues his gish gallop by trying to blame the Pacific Decadal Oscillation for global warming:

"the Pacific Decadal Oscillation causes alternating global warming and cooling for 25 to 30 years at a go in each direction. We have just finished a warming phase, so expect mild global cooling for the next two decades."

PDO does not cause global warming, it simply shifts heat around from oceans to air and vice-versa.  If PDO had caused the recent surface air warming, then the oceans would be cooling.  Instead they are warming.  Further, PDO is an oscillation.  There has been one positive and one negative PDO cycle over the past 60 years, during which time the surface air temperatures warmed approximately 0.6°C.  Sorry Evans, you can't blame PDO for that.

Tragedy of the Commons

Evans finishes up his error-riddled article with the ever more popular "CO2 limits will make little difference" argument:

"Even if we stopped emitting all carbon dioxide tomorrow, completely shut up shop and went back to the Stone Age, according to the official government climate models it would be cooler in 2050 by about 0.015 degrees."

Technically these statements are true.  Any country can argue that their nation's greenhouse gas emissions reductions alone can only make a negligible impact on global temperatures.  This even includes the USA, despite the fact that the USA is the largest historical CO2 emitter, the second-largest current emitter, and has one of the highest current per capita emissions rates.

This argument can be described as the Tragedy of the Commons: for any individual country acting alone, reducing greenhouse gas emissions could potentially cause an economic disadvantage.  And yet, if every country reduces its emissions, the net  results will be positive.  The key is to convince many countries to simultaneously act to reduce their emissions, which is the purpose of international treaties and conferences like at Kyoto and Copenhagen.  But if every nation makes the Evans argument, nobody reduces emissions, and the net result is negative.

Gish Gallop

To sum up, once you weed through the considerable empty and inflammatory rhetoric in Evans' opinion article, the meat consists of a number of long-debunked myths and gross misunderstandings of basic climate science.  Evans' article is the "skeptic" equivalent of eating red hot candies: not much substance, empty calories, but it gets the blood boiling!

NOTE: We sent an edited-down version of this article to the Financial Post and requested that they run it as a response to the Evans editorial; however, the Financial Post ignored our request

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Comments 1 to 44:

  1. Maybe it is worth saying that he is not a climate modeler nor has he published a single peer-reviewed article on climate change according to desmogblog:
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  2. Credibility or accuracy seems to not be of importance to climate deniers - they know that people will continue to cite their posts long after they get debunked. Exposing Climate Denialism
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  3. "As these figures show, estimates from both models and observational data consistently find that the most likely climate sensitivity value is approximately 3°C for a doubling of CO2. " Sorry again, but the concept of "likelihood" is totally irrelevant when aggregating a number of heterogeneous measurements and computations, none of which being really strictly speaking validated. Basing a theory of the motion of planets on the number of proposals and texts and giving a "likelihood" to the geocentric hypothesis on this criterion would have been utterly wrong - they all have been ruined by some minutes of observations of the phases of Venus by Galileo. What is worth is irrefutable scientific facts - not the number of erroneous proposals that have been made here and there. Because if the climate sensitivity has really a meaningful physical value (which is not granted) , the vast majority of all values is wrong, and if it hasn't, they're all wrong.
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    Moderator Response: [Dikran Marsupial] Trollometer reading; |=========_|

    The use of "likelihood" and "likely" in either the subjectivist or objectivist Bayesian sense is perfectly reasonable. The theory of AGW is based on well understood physics: Gilles, please go and read this book to get an idea of the historical development of the theory (it is a collection of the foundational papers with commentary) and then this book to get an overview of the basic concepts. Climate sensitivity is a well-defined physical concept, whether you grant that or not, see the IPCC WG1 report. I suggest otherwise DNFTT is the correct approach here.

  4. It is every piece of nonsense from every thread on every blog, all combined into one. I don't know what kind of mental process allows someone to keep copying and repeating these mistakes, without also reading the answers to them. And just on one old familiar line "evidence showing that the earth responds to the warming due to extra carbon dioxide by dampening the warming" - perhaps he should be asked to explain, in that case, how the climate has changed so radically in the past? Or does the "dampening" only happen when humans insist on burning all the stored carbon?
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  5. I'm just qurious about Evan's argument saying "Even if we stopped emitting all carbon dioxide [...] it would be cooler in 2050 by about 0.015 degrees." Compared to what? Compared to today? But how much warmer will it be if we do nothing?
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  6. What is every bit as frightening is the list of comments on Evan's post. Admittedly, modern publications tend very much to write for their readers, so one should expect that the readership there will be primarily, rabidly, anti-science. But it's still alarming. Sadly, at this point in time, I see two ways to get policy and understanding on track. Both are inevitable, but both will take time... at least another five years, maybe ten or fifteen. The first way is that as temperatures continue to rise, the denial engine will have a tougher and tougher time. As soon as a single year passes 1998 (and at least one in the next five will do so, if not more), the "it's cooling" argument will go away, and it's going to shock a lot of people into rethinking things. The Arctic, glaciers, extreme weather (much of which actually won't be properly attributable to climate change), and other sign posts will contribute. The second is that, quite simply, the old, tired, arrogant crowd of retired-with-too-much-time-on-their-hands deniers needs to fade away. This is going to insult a lot of people, but I'm sorry, it's true, and it needs to be said. The young need to wake up and take responsibility for and control of the future of this planet. It's far too easy for a bunch of grumpy old retired engineers who think they know it all to spend all day posting comments on blogs, dismissing the science and spewing reams of information supporting their crackpot theories. I will bet that if you conducted a poll, you'd find that 90% of the people posting the hateful, ignorant and obnoxious comments on climate change are 50+ years old, and at least 75% are 60+. The people with the least to lose by letting the planet burn to a cinder, and the most to gain by making sure things continue with business as usual, are, I am sure, that loud, vocal, aging minority whose vociferousness give the illusion that denialism is a populist movement. So as time goes on, those people will fade. Eventually, the truth will be quite undeniable, and the people who need to worry about the future (the young) will finally get motivated to wake up, learn, speak up, and take action. The "speak up" part is big. Very big. The young people of the world need to do what the youth of the 60s did in America with the Vietnam war. It needs to be important, and they need to be vocal, and they need to remind everyone that it is their lives and misfortunes that are being put on the line for other people's gain and fortunes. The young bear all of the risk, while the older one gets, the more one directly benefits from ignoring the problem. Really, this is a call to arms. A grass roots campaign of both education and, more importantly, voice needs to start in the universities of the West.
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  7. 5, Lassesson,
    I'm just qurious about Evan's argument...
    Yes, I saw that, too. I was very impressed with what a clever bit of trickery that was. "Why should we bother to change? It will barely reverse things." It's sort of like telling a cancer patient "why bother with chemotherapy, it will only shrink your tumors by 5%" when without chemotherapy the tumors will grow so fast that the patient will be dead within a week.
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  8. 7 : Sphaerica : translated into temperature, and barring any romantic hyperbole, I'm curious to know what is your prediction on the expected temperature trend for the next 50 years, as a function of the carbon emissions we could reach ?
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    Moderator Response: [Dikran Marsupial] Trollometer reading: |========--|

    Why not construct some emissions scenarios that cover what you think might happen over the next 50 (or 100) years, and then run those scenarios through a range of leading climate models, performing multiple runs for each model to capture both the uncertainty in the model physics and internal variability. Then put the results into a publically available archive so that the results can be analysed by anyone who chose to do so. Oh yeah, I forgot, the IPCC have already done that haven't they? The predictions of just that from the leading experts in the field are available in the WG1 report, why troll for predictions on blogs?

    Click image for details. I suggest not indulging Gilles' trolling (unless of course Sphaerica disagrees with the IPCC projections).

  9. Aaah, and the trolls descend to defend and detract from the exposure of deception and misinformation by yet another so-called "skeptic" (i.e., Evans). We can only assume then that said trolls fully endorse Evans' essay that was riddled with errors, hyperbole, rhetoric and conspiracy theories. When it comes to factually-based and accurate science writing Mr. Evans gets an F. He gets an A though for disinformation, distortion, rhetoric, hyperbole, entertaining conspiracy theories, and making generalizations. Let it also be known that Evans and Jo Nova are business partners (ironically in a communication firm, H/T to Glenn). Why is that relevant? Because it seems that Evans has uncritically bought Ms. Nova's misguided beliefs about the hot spot hook line and sinker. And also, Ms. Nova has been told repeatedly that her beliefs on the science pertaining to this are in error, so Evans knows that too, but insists on perpetuating myths and misinformation. Evans is thus clearly not open-minded on the science, nor willing to learn from those in the know. Perhaps Evans will surprise us and prove us wrong by acknowledging his errors and correcting the public record. That is what a reputable and credible scientist would do.
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  10. Sphaerica @6, Great post. I agree on most counts. Yes, reading the readers' comments at the FP is truly scary-- we are in an ideological battle here, and sadly one that involves money and lifestyle changes. This is an uphill battle, but the youth are going to be critical as you say-- hopefully SkS is one way of engaging them and educating them and calling them to action. I do find us thinking about the importance of the youth rather ironic when they had very little hand in what we are facing now. I wonder how they feel about that situation?
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  11. 8, Gilles,
    I'm curious to know what is your prediction on the expected temperature trend...
    That's a ridiculous question, not worth the time it's already taken to refuse to answer.
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  12. Lassesson #5, Evans is comparing the temp change to business-as-usual for Australian emissions, which are just 1.5% of global emissions.
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  13. 10, Albatross, If I remember those years properly (it's been a while), the way they feel about it is to pretty much not think about it. There's a nagging fear in the back of their minds, but one that is quickly pushed aside by the next attractive member of the opposite sex that walks by, or planned party, or stress about finals, or what not. If they're out of school, they're more worried about getting a job, and maybe moving into their own (or a better) apartment. The future and "real life stuff" isn't on their radar. They are, foolishly, trusting those who are older and have more power to take care of things, because they're busy just trying to get their lives started. This was less of an issue with Vietnam, because they were the ones being directly affected (drafted and sent to war). Their lives faced imminent derailment by the war. Climate change, by it's very nature, is a distant threat, exactly the kind of thing that they can take a pass on for now. It's really a perfect storm. The people who can affect things don't care (enough, or properly), while the people who should care, the youth, are too distracted. I think a big, big thing that climate scientists at universities could and should do is to organize their grad students to organize awareness seminars. Make sure that college students today know that it's their future with which everyone else is playing a game of poker-dice-russian-roulette.
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  14. @Albatross It is my understanding though that the Clausius–Clapeyron relation only applies to a saturated atmosphere. Is the Clausius–Clapeyron relation applied here because there is no better explanation?
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  15. dana1981 #12 Okey, then I see why you referred to it as "tragedy of the commons". But I must say that Evans was quite unclear about it, since he was talking about "to curb emissions on a world scale" and a "world government" just before he said "Even if we stopped emitting...". That made me believe that "we" included me and everyone else in the world.
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  16. Lassesson #15 - to be fair, the article was originally a speech given at an anti-carbon tax rally in Australia. In that context it's a bit clearer.
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  17. Can anyone comment on the Clausius–Clapeyron equation? This is interesting to me as Ralph Cicerone made a similar argument in congress but Richard Lindzen rebutted him and said that the Clausius-Clapeyron equation tells us nothing about our atmosphere(paraphrasing).
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    Moderator Response: [DB] Jay, I believe Chris Colosse covered that in this post: What would a CO2-free atmosphere look like?, in which he deals with the specific testimony you mention.
  18. Jay, I recommend this document from Pierrehumbert et al.
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  19. Jay Cadbury, Richard Lindzen was correct to point out that C-C only tells us the upper bound on the amount of water vapor that can build up in the atmosphere (i.e., for any given temperature, C-C tells you how high you can make the partial pressure of water vapor before the vapor starts to condense into liquid or ice). C-C doesn't actually say anything about whether that upper bound is reached, and in fact in a global sense, the atmosphere is not at saturation. Even more to the point, there is no simple theory for how the free troposphere humidity should change in a warming world, as this involves an interplay between dynamics and fluid dynamics and cannot be reduced to the C-C relation. What's important for the water vapor feedback however is that the water vapor "concentration" goes up with temperature, and if *relative humidity* is nearly invariant over a small range of temperature changes, then that means the vapor pressure at least scales with the percent increase you'd expect from C-C, so both the saturation and specific humidities must rise proportionally. Even if relative humidity goes down by some unknown drying mechanism, it would take quite a bit for this to overwhelm the C-C equation and force the feedback to be negative, and this is not seen in any observations or models, and is completely inconsistent with the magnitude of climate changes in the past. There are conceivable ways in principle to make a negative water vapor feedback without violating any first-principle physics, and Lindzen proposed one idea for doing so back in the '90s but observations didn't support his hypothesis...that's when he gave that idea up and jumped onto a cloud thermostat instead, the so-called "IRIS hypothesis." A large number of papers by the likes of Brian Soden, Andrew Dessler and others who work at the interface of modeling, observations, and theory have shown that the water vapor feedback is unequivocally positive.
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  20. If someone wanted to know if this site was worth his or her time, I would point to this post (and the comments) and say, "If you care about the havoc we're unleashing on ourselves with carbon pollution, this is THE site for debunking those who would sell your future for their current profits." I've talked to groups of young people from about age 12 through college about climate change, and trying to get them to understand the urgency of the situation is very hard. A small percentage of them get it before you open your mouth and nearly all of the rest smile, nod, and then go about life as if the presentation never happened. It's about as depressing as anything I've experienced.
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  21. Thanks Lou, that's nice of you to say. Agreed, people have a very hard time understanding long-term dangers. They won't do anything until the consequences are smacking them in the face.
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  22. @20 Lou Grinzo: "I've talked to groups of young people from about age 12 through college about climate change, and trying to get them to understand the urgency of the situation is very hard. A small percentage of them get it before you open your mouth and nearly all of the rest smile, nod, and then go about life as if the presentation never happened." Lou; is the comprehension of the subject, by these students, due to intelligence or curiosity?
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  23. Lassesson #15 Dana1981 #16 Re: "Even if we stopped emitting all carbon dioxide [...] it would be cooler in 2050 by about 0.015 degrees." Whether he was talking about Australian emissions (which he was) or global emissions, the figure seems wrong. If we stabilise at 390ppm tomorrow, we've still got 30 years warming in the pipeline (takes us to 2041). We're not going to lose 30 years worth of radiative forcing overnight and go back to today's temperatures (minus a little bit) in only 9 years are we? - what about the longer term feedbacks which would be coming into play by then anyway? As I pointed out before, this seems to be a new denier meme popping up all over the place. It basically goes: - there's virtually no point in making a huge effort now because it will have almost no effect. The meme purports "no effect" to mean global temperature being the same or less in 2050. It sneakily ignores that if we do nothing or not much, global temperatures will be up and rising fast in 2050. It looks to me like one of the more outrageous pieces of grossly twisted thinking from the denialist propaganda factory. I liked Spaerica's comment at #7 It's sort of like telling a cancer patient "why bother with chemotherapy, it will only shrink your tumors by 5%" when without chemotherapy the tumors will grow so fast that the patient will be dead within a week. although I think we need a different metaphor for public use.
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  24. Nick - the number Evans gives is reasonable for the temp change avoided at equilibrium compared to business as usual. It's just small because the Aussie population is small compared to the global population.
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  25. Nick, what you've also got to remember is that if we manage to cut global CO2 emissions back to 1990 levels, then there's also the possibility that new & existing carbon sinks might be able to take up some of the excess CO2 already in the atmosphere. This will be even more likely, of course, if we can cut our CO2 emissions back to pre-1950 levels. Maybe I'm being overly optimistic, but one can always hope.
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  26. dana1981 at #24 Crikey. I really must learn to stop underestimating the stupidity/sneakiness of the "sceptics". You mean the figure Evans used was him saying that if Australia achieved zero emissions from tomorrow that the equilibrium temperature in 2050 would be 0.015 deg less than it otherwise would have been? In other words he meant it would be a tiny bit less hot, not cooler? That really is twisted rhetoric that looks to me like it was crafted to misdirect the listeners.
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  27. @Chris Extremely interesting and informative post. Evans: "Why does official science track only the surface thermometer results and not mention the satellite results?" "This would be a good question, if it were remotely true. In reality, "official science" pays very close attention to satellite temperatures. For example, they're discussed in great detail in the IPCC report and highlighted every single month by NOAA." I am confused here because I have read some scientists who say that the surface and satellite data does not match. "The satellite data shows little long term warming. Ground station data shows a lot of warming. The ground-station data has serious systematic problems with the urban heat island effect and station dropout over the years. I put much more faith in the satellite data. “Satellite data” normally means the temperature of the lower troposphere, not the surface temperature. Have a look at the attachment."-Dr. Happer I will post his attachment shortly, as I am waiting for it to finish downloading.
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  28. He sent me a pdf, which you can download here.
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  29. Here is a pull quote from the article that concerns me. "The world’s surface observing network had reached its golden era in the 1960s-1980s, with more than 6000 stations providing valuable climate information. Now, there are fewer than 1500." This concerns me because 1500 stations does not seem adequate enough to measure the entire system. Secondly, what range are these stations accurate up to?
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  30. Jay @27, Your questions have been answered in the main post. The long-term trends in the satellite data and surface data are in good agreement, especially the between the RSS products (which are superior to the UAH data that the contrarians are so focussed on) and the surface temperature data. Why don't you look at the data yourself (trends for 1980-2010) at Tamino also has a good post on this issue, well worth the read. Either way, Evans was completely wrong to state that the "official" science do not track the satellite data. I'm sure that we can agree that Evans was demonstrably wrong on that point. And be wary of uncritically citing "information" from political lobby groups like the SPPI-- recall Monckton is with them too, and he has been debunked more times than I care to recall.
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  31. It is also worth noting that the various surface station products measure slightly different things (e.g. coverage of poles), which are again slightly different from what the satellite products measure (surface rather than lower trophosphere), so you wouldn't expect them to be exactly the same anyway.
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  32. Interesting, Jay, you do realize that the GOP want to slash NOAA's budget, right? And now we have contrarians arguing that the station dropout is an issue. Anyways, the station dropout has been demonstrated to be a non issue by the CCC. This is not big nor is it recent news. Please, instead of obfuscating, your credibility would be much better served by actually calling Evans on the myriad of errors in his speech/essay. Why are "skeptics" so unskeptical of their own, and so reticent to critique their own or call them on their errors? Mind you I should not complain, it is for this very reason that "skeptics" will probably always have a huge credibility issue. PS: Re the station issue, please read this (see last question).
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  33. Jay @ 29... Regarding the satellite data and the surface station not matching, I wonder if you're pulling up old data somehow. Or maybe someone else you're reading is referring to old data. For quite a while there was a discrepancy between the satellite data and the surface station data. There was a big rift where no one was understanding why the two methods were returning different results. This went on for quite a while. Then an outside group was reviewing the UAH satellite data and discovered that they (Spencer and Christy at UAH) were not accounting for orbital decay of the satellite. That decay introduced a cooling trend (or less of a warming trend) into the UAH data. Spencer and Christy finally had to admit that their data was in error and correct it. Once they did their data matched the surface station data sets almost perfectly.
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  34. "The assumption is simply that the Arctic Ocean as a whole is warming at the average of the stations around it. What people forget is that if you don't put any values in for the areas where stations are sparse, then when you go to calculate the global mean, you’re actually assuming that the Arctic is warming at the same rate as the global mean. So, either way you are making an assumption." Albatross I understand his point about having to put in values for where stations are sparse but I would be more at peace if they added more surface stations. And this is what is frustating to me, at the last congressional hearing, Lindzen was arguing with the scientists on the other side about the surface station measurements and the issue went unresolved.
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  35. Jay @34, "but I would be more at peace if they added more surface stations" I'm sorry, but you being at peace does negate the findings that one does not need a needs a plethora of data to adequately monitor the global mean surface temperature as was so nicely shown by CCC and as was eloquently stated by Dr. Schmidt. But if you feel strongly, then I encourage you to please contact your government and ask them to stop cutting funds to monitoring programs. Now to get back to the topic at hand, you have still to condemn Evans for his misleading statements, so I can only assume then that you support said misleading statements.
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  36. Nick #26 - yes, you've got it right there. Evans didn't word the sentence very clearly.
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  37. As far as more surface stations is concerned, that's the whole upshot of the Berkeley Earth Surface Temperature study. They are incorporating 39,000 stations into their data. But, the initial findings are showing exactly what all the other data sets are showing. We need to wait to see what the full BEST study says but indications are that more stations is not going to change the result.
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  38. Lassesson #5, 15 Sphaerica #7 dana1981 #12, 16, 24, 36 Nick Palmer #23, 26 Surprice! The same skeptic argument that I thought Evans was making is now available with a rebuttal here at SkS - CO2 limits won’t cool the planet. Aparently, that was not what Evans was talking about (even if it can be misinterpreted that way - if that was intentional or not, I don't know). Instead he was referring to the same argument as Mr Monckton did in his myth #15 when he said that "CO2 limits will make little difference". This is often referred to as Tragedy of the commons where one individual can argue that his/her contribution will not matter, since there are too many others that will have to make the same contribution to have an effect. I propose that we continue this discussion in the blog post or the rebuttal connected to "CO2 limits won’t cool the planet", if we have anything more to say about it.
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  39. Folks, Evans is at it again with a new document dated September 2011. A Link to the pdf can be found here if you want to copy and paste into a browser or here it is an embedded hyperlink Time for an updated rebuttal please dana?
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  40. @39 Mark I followed your link and somehow ended up at jonova's site Wow that is a mud wresting pit! KR to great credit has taken up the argument and the rebuttal is sound and patient but alas it has fallen on "itchy ears". The argument is not one that can be won by science alone I fear. A biblical quote applies: "2 Tim 4:2 Preach the Word; be prepared in season and out of season; correct, rebuke and encourage--with great patience and careful instruction. 2 Tim 4:3 For the time will come when men will not put up with sound doctrine. Instead, to suit their own desires, they will gather around them a great number of teachers to say what their itching ears want to hear. 2 Tim 4:4 They will turn their ears away from the truth and turn aside to myths." From what I have learned here each of the four points (myths perpetuated) raised by Evans can be debunked but the deaf cannot hear the truth above the noise trapped in their heads.
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  41. oneiota - Thanks for the feedback re: the JoNova thread. I find the posters there generally sincere, if often mistaken, with a smaller percentage than Watt's site being actively nasty. And at times they appear to listen... I dropped that thread when it got down to about three posters with, ahem, "unique" perspectives on climate change, unwilling to consider other points of view. While a bit exhausting, I suspect that presenting the consensus view, as supported by the data, is at least potentially informing those on the fence. I've received the occasional compliment there on being willing to discuss matters, for presenting links to peer-reviewed papers and also reading what others link to, and I treasure a particular moderator comment to a ranting poster along the lines of "Please shut it - while I disagree with KR, you are making him look reasonable..." :)
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  42. Evans has a (new?) somewhat similar article that is being cited by "skeptics". He argues that net feedback is so strongly negative that climate sensitivity is perhaps as low as 0.25 x 1.1 = 0.275 degrees C per CO2 doubling - although he allows that it may be as high as 1 C per doubling. (No citation for that claim though!) And at the bottom the article cites his Electrical Engineering Ph.D. - and argues that EE is "...The area of human endeavor with the most experience and sophistication in dealing with feedbacks and analyzing complex systems...". That's particularly interesting, because the article argues that:
    If a system instead reacts to a perturbation by amplifying it, the system is likely to reach a tipping point and become unstable (like the electronic squeal that erupts when a microphone gets too close to its speakers). The earth's climate is long-lived and stable — it has never gone into runaway greenhouse, unlike Venus — which strongly suggests that the feedbacks dampen temperature perturbations such as that from extra CO2.
    This argument would garner him a Fail in his undergrad automatic control theory classes. He is effectively suggesting to his uninformed audience that there can only be either positive runaway feedback or negative ("dampening") feedback - and that positive non-runaway feedback that merely amplifies a signal does not exist (in practice, perhaps even in theory). His former EE professors might want to have a quiet word with him on that point, as would many amplifier designers. And there's more to dig into in that article...
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  43. And also, Ms. Nova has been told repeatedly that her beliefs on the science pertaining to this are in error, so Evans knows that too, but insists on perpetuating myths and misinformation.
    She is still making that claim as well - e.g. in comments here.
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  44. Tom @ #45 My response was very much on topic because ... The very first section of this article is about climate sensitivity and it discusses the assumed feedback of water vapour which is supposed to reduce carbon dioxide's effect to 1.2 out of 3.0 (which I calculate as 40%, though the author of this article calculates as "one-third") So I was explaining why water vapour does not have such an effect because (a) it sends some of the solar IR radiation it captures back to space, thus cooling and (b) the backradiation it (and carbon dioxide) quite correctly do create is actually only all standing waves which cannot transfer any energy to the surface, but can slow radiative losses, even though diffusion and evaporation then compensate.
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    [DB] "My response was very much on topic because ..."

    Incorrect.  The topic of the thread was about David Evans' Understanding of the Climate Goes Cold.  As is your wont in this forum, you then proceeded to make this about your misunderstandings of physics and climate and not about the topic of the thread.

    You then compound things by threatening to smear SkS on other venues.  That is reflective of both you and the nature of those venues that will tolerate that type of posting.

    As this is a pattern of behaviour of long standing with you, you are no longer welcome here.

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