Wednesday, 19 May 2010

Has the greenhouse effect been falsified?

Reduced image from A First Course in Atmospheric Radiation, by G. W. Petty.

My latest blog is a guest blog at the excellent site Skeptical Science, by John Cook.

My contribution is now one of the collection of pages showing what the science actually says about some of the arguments used by so-called climate skeptics. It can be found at Has the greenhouse effect been falsified?

The main source of this claim is the paper by Gerlich and Tscheuschner, uploaded at arxiv in 2007 and then, incredibly, published in a physics journal in 2009 as an invited review paper.

Now in fact, this is not a particularly common skeptic argument. It has been picked up by a few people who will latch on to any argument, however ridiculous, if it can be seen as a way to combat the science behind the discovery and study of global warming. But its spread has been rather limited, since the argument has been quietly ignored by most skeptics with any background in science.

More sophisticated critics of conventional science tend to recognize that there is such a thing as a greenhouse effect, and then take some other line of denial, such as to dispute the existence of positive feedbacks in the impact of a changing greenhouse house effect, or the contribution of carbon dioxide to the effect, or something else.

My essay dives in head first to scrape from the bottom of the barrel of climate denial, and then simply holds up for comparison what the science actually says on the subject. I'm very happy with the end result, and encourage any readers I might have to take a look at the new page on Skeptical Science, and if you are new to that site then have a look around the rest of it as well! It is an excellent resource.

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Saturday, 8 May 2010

Published rebuttal to Gerlich and Tscheuschner 2009

Early in 2009, an unusual paper appeared in the International Journal of Modern Physics (B), claiming to falsify the atmospheric greenhouse effect using physics. The authors are Gerhard Gerlich, of the Technical University Carolo-Wilhelmina in Braunschweig (Germany), and his colleague Ralf Tscheuschner. Amongst other things, it claimed that a violation of the second law of thermodynamics was required in conventional descriptions of the atmospheric greenhouse effect.

The paper had little impact in the world of science, although there has been a lot of discussion at various blogs.

In response to this, a number of people, led by Joshua Halpern of Howard University, have submitted a rebuttal. The rebuttal, and a reply from the authors of the original paper, Gerhard Gerlich and Ralf Tscheuschner, has now appeared in the April 20, 2010 issue of the journal. The papers are, unfortunately, behind a paywall. However, you can can see the original paper on arxiv at arXiv:0707.1161v4. The abstracts for the rebuttal and reply can be found online at the pages for IJMP(B), Vol 24, Iss 10, Apr 20, 2010.

I am one of the co-authors of the rebuttal, under my own name of Chris Ho-Stuart, so I am deeply involved in this.

I expect there will be a lot of of discussion on this in various places around the net. I have opened up a thread at the new Climate Physics Forums discussion board. This may be a good place for discussions to occur. The board aims to maintain high standards of courtesy and substance, while allowing robust criticism of ideas.

You may find the discussion thread at Published comment, and reply, on Gerlich and Tscheuschner 2009. I would very much prefer people to discuss this post at the board. You will be required to register in order to comment, but the process is painless. However, I am also leaving comments open here for the time being.

The board has no formal policy on correct views of climate, and so criticism or skeptics of conventional climate science are very welcome. My views are not board policy.

Since I am the moderator of the board at present, I have a conflict of interest, and so I will be particularly careful to be fair in applying the board guidelines consistently, and being open to criticism of any moderation decisions that are necessary. The board is also advertised at my previous blog post Climate Physics Forums now going public!


I am collecting other links to discussions of this.

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Tuesday, 4 May 2010

Climate Physics Forums now going public!

Climate is a hot issue these days. There's lots of people involved in talking about it and explaining various aspects from all kinds of perspectives.

There is a niche here for a place online where people can talk about it. I offer to those interested such a place: Climate Physics Forums.

There are already many ways in which discussions occur. Blogs are a form of discussion; and the comment streams have many exchanges going on all the time. Many bulletin boards exist which support discussions on climate as well. Having a range of venues is a good thing, and I think the new forum will be a useful addition.

I am planning to have a formal launch in late June, and will have more details about that as it approaches, but there is no need to wait until then. The board is open for business now, and now is the time to help join in and give suggestions for its direction and seed it with initial content.

The bulletin board format is a good one for managing threads of discussion. There's also scope for better and more efficient oversight, and lots of scope for supporting a range of parallel discussions of different kinds.

Climate Physics Forums is intended to work with two primary principles.

  • Courtesy for all contributors.

  • Focus on what is going on with working science.

(1) Courtesy

Climate discussions get very heated. Often there are strong mutual accusations of bad faith flying around. And indeed, there is a place for strident militancy in a flawed world. But that place is not going to be this bulletin board.

This is intended to serve as a safe haven for people to talk and express disagreements, family friendly, with young people welcome and encouraged. Taking a line from wikipedia, I ask people joining in to assume that everyone there is in good faith trying to be constructive. Even if they aren't, we still assume the unlikely and engage as if they are there in good faith. Pejorative speculations about other people's ethics or motives or intelligence are unwelcome; no matter who they are directed against.

Tear apart ideas by all means; but distinguish that from tearing up the person.

(2) Substance

This is not intended to be open to any old idea presented as if it was a credible scientific notion. The idea here is to support learning and investigation of what is going on in the world of science, and that means basically what gets published in the scientific literature.

This still allows for a huge range of topics and competing ideas. We often talk about "consensus" in climate, but this is not going to be a requirement. Science thrives on dissent and a range of views, and so if it gets published in legitimate scientific outlets, then we can consider it. This means, of course, a lot of claims that are incorrect can be raised and argued in the forum; since the literature is no assurance of correctness.

Scientific peer review does not establish ideas as settled and correct; it rather establishes then as worthy of consideration by the scientific community (ideally...). That's the way it is taken at Climate Physics Forums; what has been reviewed and published becomes worthy of discussion.

Hence, Climate Physics Forums is not a place to develop your own personal theories, or to reform the world of science. It's a place to consider what scientists are publishing, good or bad alike.

Regardless of my own views, the board has no policy on correct answers. Only on how issues are to be addressed. Neither is it presumed that there has to be a balance between opposing views. Some views are just wrong, and the idea of debate is to help sort out what's what. But the board does not declare as policy any of the acceptable answers, and it is expected that members will continue to disagree with each other, and hence that some members will be actually wrong about some things. No problem; you are still welcome!

(3) Moderation

The moderation policies are still being sorted out, but the underlying philosophy is this.

Moderation is there as a service to the community, not as a privilege to moderators. Moderation actions are never seen as "punishments". All moderation actions should be geared to helping people use the forum effectively.

Banning of members should be thought of as a case where the moderators have failed. They have been unable to help someone use the forum. It means that the workload of moderation has become too great, and time can no longer be allocated to helping that person. Normally, the way of managing members who need a bit of extra guidance will be to apply a moderation filter.

By default, anyone can register freely and post immediately; inappropriate posts can be reported and staff may choose to put some members on a filter so that their posts will be checked before appearing.

Feedback and suggestions will be very welcome, especially at this early stage.

Ideas for things we can do at the formal launch would be great. But for the next few weeks the board is up and being tested out as we see how it might all work.

I have deliberately refrained from adding all the features or forums or ideas that could be possible. It is best to start small, and add features with the help and the input of members. That's you, I hope!

I have found it is a very useful way to learn about a topic to practice explaining it for others! So I'd love to have people join in and try out their hand at explaining some topic or issue or question, in line with the guidelines. You can do this at any level you like. I hope you will get practice in explaining things, and take that experience away with you into the wider world. I hope you will get useful feedback and ideas for what responses you can expect.

I invite people interested to have a look, checkout the guidelines, and start to have an input. I engage there as the board owner, with user name "sylas".

The image associated with this post is the NOAA-19 satellite, the latest of this series of sophisticated monitoring instruments which is now helping gather data that helps sort out how the physics of our climate works. It an artists's impression used with the kind permission of Lockheed-Martin, who developed the satellite.

So, come one, come all. Climate Physics Forums is open for business and looking for content and ideas.
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Tuesday, 30 March 2010

The littlest skepchick

De niece — she of the story I've seen a scientist — is my new hero. She blew me away with this latest effort. The scientist must have had an impact.

Recently she lost a tooth, and she knows the tooth fairy will give money for a tooth under the pillow. However: she’s a skeptic (at age 5). She was talking to me about the big event recently, and mentioned that she wasn’t sure if there really was a tooth fairy. I was interested to hear more, and asked her what she thought.

I swear to you, people; she then came up with this, right there and then, all by herself. An idea to test her theory. She decided to count all Mum and Dad's money. Then, the next morning, she could tell if that was where the money came from.

Woah! I was impressed with that. But I just said that sounded like a very clever idea. With that small encouragement, she put the plan into practice. She told her Mum and Dad what she wanted to do. (I shall have to teach her about experimental control protocols later on, I guess.) They also were impressed, and in line with their own feelings on such things, they decided to be completely fair with her on this one. They are quite happy to play the games of childhood and magical beings, but faced with a small and trusting scientist, the path was clear. They told her nothing, but helped her find and count all the money.

The next morning, she had her brand new two dollar coin, as usual. And she went ahead and counted all Mum and Dad’s money. No cheating had taken place, although to make life a bit difficult it had been a pocket money day, and there was deduction to make. But de niece has her uncle's genes, and numbers are no problem. She ran all the calculations and sure enough, Mum and Dad had two dollars missing; a confirmed prediction and falsification of the null hypothesis.

So now she knows: and she is pleased as punch at having figured it out. She asked Mum point blank if Mum was the tooth fairy, and Mum had to confess the truth. The excitement of discovery far outweighed any disappointment at loss of the story. The problem, however, was explaining to her that she couldn’t go ahead and tell all her friends at school.

Basically, however, she got it in the end. This is a game that parents play with their children, and now she’s in on the game too, and she shouldn’t spoil the game for other children. She now knows there’s a tooth fairy — and knows also who the fairy actually is! And it’s a secret, which other children will find out in time from their own parents. So when teacher asked her if the tooth fairy came, she was able to answer yes, and then later on in private explained to her teacher that now she knew the tooth's fairy's alter ego.

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Sunday, 20 July 2008

The APS and global warming: What were they thinking?

From the "what were they thinking" department…

The "Physics and Society" Forum of the American Physical Society decided to open up their newsletter to a nice respectful debate on the main conclusion of the IPCC: that "anthropogenic CO2 emissions are very probably likely to be primarily responsible for the global warming that has occurred since the Industrial Revolution". From there, things went downhill quickly!

Two articles appear in the forum's July 2008 newsletter. The "pro" case is A Tutorial on the Basic Physics of Climate Change, by David Hafemeister & Peter Schwartz. The "con" case is Climate Sensitivity Reconsidered, by Christopher Monckton.

Monckton is rather … notorious … for those who follow these debates; and an extraordinary choice for a physics journal. His article has lots of formulae but little insight or competence. It did not take long for things to turn ugly.

In short order, half the blogsphere fell over themselves in triumph that the APS had reversed its long standing recognition of the facts of anthropogenic global warming; and gleefully concluded that the APS with its 50,000 strong membership could now be added to the ranks of the denialists. Fulsome praise was heaped upon Monckton's article as a brilliant mathematical refutation of the IPCC conclusions. It did not take long for the APS to add to its front page a plain statement that there had been no reversal of position; and add in red ink to the top of Monckton's article a notice that it had not been subject to scientific peer review, and drew conclusions that were in "disagreement with the overwhelming opinion of the world scientific community" and with the Council of the American Physical Society. Monckton hit back immediately with a letter demanding an apology and retraction.

How this all plays out will be most interesting to follow. The initial decision by the APS editor was extraordinarily naïve. I don't know what they expected to achieve with this; but whatever happens now it's a big win for Monckton and his fans. He's got a pulpit, and any response will be dismissed as scientific close-mindedness. Treating it as a serious debate is all that the denialists really want to achieve. Firing the editor (as some have suggested) is surely an over-reaction that would only make everything even worse.

Hey ho. I'm going to watch the social developments with interest; and attempt a minor contribution of my own just to indicate some of the errors, in my opinion, in Monckton's article.

There are, by the way, bound to be errors in my analysis as well. I'm posting it because I'll welcome feedback or corrections -- from anyone -- and because I think it is much better to focus on the substance of article, now that it has been published. I'm not an expert, but I co-incidently was reading many of the relevant papers used also by Monckton just recently, and so am willing to risk this attempt at analysis.

Basically, Monckton looks at the matter of "climate sensitivity" and feedbacks. For a useful review paper on the background to this topic, I recommend How Well Do We Understand and Evaluate Climate Change Feedback Processes? by Sandrine Bony and thirteen other authors; in Journal of Climate, vol. 19, issue 15, pp 3445-3482. (37 pages) You can also get a preprint by ftp from University of Washington Earth Observing System. It comes with a very handy little appendix to explain how climate feedbacks are quantified. Monckton also refers to this extensively.

I'll skip down to Monckton's attempt to use "The IPCC’s method of evaluating climate sensitivity".

Part 1. An attempt to use the IPCC's method

It starts out ok. There is a formula used for the temperature change that should be expected for a doubling of the concentration of CO2. It is:
ΔTλ = ΔF2x κ f
The variables here, using Monckton's naming conventions, are
  • ΔTλ This is the change in temperature than should be expected from a doubling of CO2 levels.

  • ΔF2x This is the "forcing", or the change in the energy balance at the top of troposphere, which results from a doubling of CO2 levels. It has units of Watts/m2.

  • κ This is the "base sensitivity", or the expected response of the Earth's temperature, per unit forcing. It has units of K W-1 m2.

  • f This is a dimensionless multiplication factor, capturing the effect of various climate feedbacks to amplify or damp the temperature response.

Monckton then correctly notes (eqn 3) that ΔF2x is about 3.7 W/m2. This follows from some basic physics, albeit obtained with difficult integrations across the spectrum and along the atmospheric column.

Everything from this point goes rather pear shaped. He makes a completely different use of the variable, to represent some kind of total anthropogenic forcing associated with a CO2 doubling, using a rather confused set of extrapolations from other effects. Basically, he takes the 3.7, scales it up so that it stands for 75% of a total forcing from other greenhouse gases, subtracts a fixed amount for aerosol cooling, and finally applies a "probability-density function" correction which has me baffled. The probability density functions for combined 1750-2005 forcings are in figure 2.20 of IPCC 4ar; It looks a bit like Monckton has taken the mode of 1.72 for the distributions by adding up best estimates for each individual forcing, and then scaled to get the mean 1.6 of the combined distribution (which is a bit skew) as given in section 2.9.2 of IPCC 4ar. Anyhow, after all of that weirdness, he ends up with about 3.4 as a forcing value; which is no longer a doubling of CO2 forcing but a strange kind of combined forcing not properly associated with any meaningful bench mark.

However, it is a forcing; so let's see what he does with it next.

His value of κ as 0.313 K W-1 m2 is uncontroversial. See the reference to Bony et al (2006) I link above.

The feedback multiplier contains more weirdness. Monckton includes a 0.25 "CO2 feedback", which is actually about the changing rate at which carbon is taken up from the atmosphere into the other reservoirs of the carbon cycle. This is discussed in section 7.3.5 of IPCC 4AR. What it means is that the fraction of emissions removed from the atmosphere reduces as carbon is being taken up and as temperatures increase; so that the same level of emissions results in a greater CO2 concentration.

This is not a feedback in terms of more temperature per unit forcing, and should not treated as such. Adding the 0.25 term is an error here, and it becomes very obvious as an error later in Monckton's article.

In any case, Monckton gets 2.16. He'd have been better to stick with 1.9; which is the actual feedback parameter. The accuracy of this number is low; certainly not enough to justify two decimal places.

The gain is then obtained as (1-2.16*0.313)-1, which is 3.077; far too many figures of accuracy. The errors in the 2.16, combined with the subtraction, mean that this number is only accurate to about +/- 1

Also, it should be (1 - 1.9*0.313)-1, which is more like 2.5.

Finally, he multiplies everything together to obtain 3.405 x 0.313 x 3.077 ≈ 3.28. Using the correct numbers, this would be 3.7 x 0.313 x 2.5 ≈ 2.9.

Monckton congratulates himself for "demonstrating that the IPCC’s method has been faithfully replicated" because his value of 3.28 is close to the central point of the range offered by the IPCC, being from 2 to 4.5.

However, what the IPCC actually says (technical summary) is:
Analysis of models together with constraints from observations suggest that the equilibrium climate sensitivity is likely to be in the range 2°C to 4.5°C, with a best estimate value of about 3°C.

So in fact, if Monckton had simply used the 3.7 forcing and the correct feedback parameter of 1.9, he'd have got much closer to the IPCC conclusion, and would have been following their methods.

So far, the errors don't have a lot of impact, but they demonstrate a level of basic misunderstanding that does not bode well. From here, things go downhill fast.

Part 2.1 Adjusting the numbers. The forcing.

The first and major step is a look at radiosonde data for warming in the troposphere. This is a notoriously difficult area, as the radiosonde record has well known systematic errors, which have been discussed now for decades. A couple of recent papers have come out just this year which address many of the issues by using wind shear information. Specifically:

Basically, the mid-troposphere warming is indeed present, as expected.

Monckton does cite this new research, but dismisses it on the basis of satellite records... another case where measurement and calibration errors are a source of hot dispute. In any case, let it go... because what Monckton does with this is astounding.

He divides the forcing by 3. (equation 17)

That's just surreal. There's no basis to reduce the forcing here. It's the temperature response that is involved. He gives a vague appeal to Lindzen (2007), Taking greenhouse warming seriously, in Energy & Environment 18 (7-8). But that paper does not propose any reducing in forcing; only to sensitivity... on roughly the same dubious basis of limited troposphere warming.

Part 2.2 Adjusting the numbers. The no-feedback sensitivity.

Here I confess to sharing a concern with Monckton. I've been looking at these papers now for a couple of months now for another discussion, and I also have tripped up on how this parameter is defined. I've been reading the same references Monckton gave in his paper (Soden, Bony, Colman etc) and I don't really get how the value of -3.2 is obtained. I can understand the -3.7. If anyone reading this would put a comment or a pointer to help clarify, I'd appreciate it!

But in any case. For this next calculation it become obvious that including the carbon dioxide feedback term of 0.25 as part of the feedback parameter b was an error. Monckton uses his 2.16 feedback parameter for a fixed CO2 forcing taken from observations. But that 2.16 included the curious 0.25 addition intended to account for changes in how carbon is taken up into the carbon cycle. It definitely can't apply here, where direct measurement of CO2 levels are being used.

There is also the bizarre use of a "mean" between two totally conflicting sets of measurements; based on NCDC, and a rather strange halving credited to McKitrick. It should be two alternative values; not a mean. And by using 1.9 rather than 2.16, you should get about 0.31 from NCDC values and 0.22 from the halved temperature.

This is not a sensible way to estimate κ, but in fact using the NCDC it gets close to the original value being used. But now Monckton is "double" dipping, in diverting the number down based on McKitrick... because this is ANOTHER reference to reduced warming trends... already used above to reduce the forcing estimate.

(Hat tip also to Tim Lambert, who notes this same error at the Deltoid blog: Monckton's Triple Counting.)

Part 2.3 Adjusting the numbers. The feedback gain.

Monckton looks immediately to maximum upper bounds here; which conceals another subtle error. The various feedback parameters are not independent of each other.

In particular, the magnitude of a water vapour feedback (positive) tends to track with the magnitude of the lapse rate feedback (negative), since both become stronger with more water vapour in the atmosphere. Water both has a greenhouse effect for a positive feedback, and a weaker lapse rate for a negative feedback. You can't maximize both together; their sum shows less variation than either one by itself.

The actual range of all feedbacks together is available in Bony et al: it is about 1.5 to 2.6

There's no problem with the maximum exceeding the 1/κ value of 3.2

There's also a curious point that Monckton has already proposed a lower value for κ, which raises 1/κ to a bit over 4; but that is a detail. The fundamental error here is in simply adding up the upper bounds of feedbacks. They are not independent values; but are obtained as tuples from a range of models. Details in Bony et al (2006).

Part 3. Conclusion

Monckton's paper looks superficially impressive, but examination of the equations betrays some fundamental confusion on the physics and climate science involved.

  • Dividing a forcing by 3 makes no sense at all, and is directly in conflict with Monckton's own reference to a much more able skeptic, Lindzen. The proper argument from temperature is not that the forcing is wrong, but that the sensitivity is wrong.

  • The climate sensitivity is the temperature response to a certain forcing. Personally, I'd prefer to see people using sensitivity as temperature change per unit forcing; but there is a strong tradition for temperature change per forcing due to doubled CO2. In either case, all Monckton's effort to obtain some kind of mean anthropogenic forcing is precisely the wrong way to consider sensitivity. The forcing used throughout his analysis should be 3.7: finis.

  • The carbon dioxide feedback term is not appropriate in a consideration of sensitivity. The feedback parameter should be 1.9 whereever Monckton uses 2.16.

  • The whole recalculation of κ is flawed. The method is dubious, but if properly applied it actually gives close to the right value, near to 0.31. Holding the feedback parameter fixed as a way of calculating κ is backwards; it is the feedback parameter which is most uncertain.

  • That being said... any commenter who can give me a good explanation of how to get 1/3.2 for κ please do so! I can get about that using a grey-body emissivity relation, based on surface temperature and atmospheric emissions, but that sounds wrong. Holding lapse rate fixed and mean emission height fixed just gives the good old 1/3.7.

Monckton's best case here is simply the alleged lack of mid-troposphere warming. All the maths stuff is so badly flawed that it detracts from the shreds of what argument might be salvaged. The issue of troposphere warming will continue to be a focus of interest and debate; but skeptics invariably fail to take proper account of the large error bars on the old troposphere temperatures they invoke; and with the recent work on wind shear this argument, which was never strong, is looking more and more dubious.

Update: (July 26) Gavin Schmidt at realclimate has a response as well: Once more unto the bray. Gavin, by the way, is the real thing; a scientist active in climatology, and in public communication efforts, and with a daunting record of directly relevant formal scientific publication. He also linked to my little blog! Me and Gavin, yeah, that's the ticket.

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Friday, 27 June 2008

Cectic is brilliant

Go read the ever-brilliant Cectic online comic. I've reproduced here one panel from the latest comic: Brain On, Brain Off. You'll have to go to the original for the punchline. Ah, if only education was that easy.
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Tuesday, 3 June 2008

Because it is beautiful

Image of a transluscent cranchiid squid from NOAA's ocean explorer.
I've just had an aha moment. Someone just said something simple, obvious, and—if you are interested in communicating science—useful.

When we are writing about some topic in science for the general public, how do we foster a recognition that the topic is worthwhile? How do we motivate people to take an interest in something they are not familiar with? Or be sympathetic to funding? Sometimes we are advised to emphasize the importance of the topic.

That only works occasionally. PZ Myers has a much better idea. (Hat tip to Scott Hatfield for a video of PZ explaining.) If you have a cure for cancer, then fine; importance will work. But if you are explaining the age of the universe, or Martian geology, or biological evolution, emphasizing importance is not your best approach. PZ suggests you think writing for your plumber.

The importance of, say, biological evolution, is not an easy sell. It's not going to make much difference to the plumber's life. But just about everyone gets the value of beauty. Let people share some of your excitement because it is neat.

PS. Here is an example of how it is done, from the master. PZ asks, and answers: how do you make a cephalopod drool?

PPS. PZ himself is third in line to blog on his lecture: My crimes are being documented.

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