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How not to write a press release

Filed under: — gavin @ 21 April 2006

A recent BBC radio documentary on the possible over-selling of climate change, focussed on the link between high profile papers appearing in Nature or Science, the press releases and the subsequent press coverage. One of the examples chosen was the Stainforth et al paper that reported the ranges of climate sensitivity within their super-ensemble of perturbed physics runs. While there was a lot of interesting science in this paper (the new methodology, the range of results etc.) which fully justified its appearance in Nature, we were quite critical of their basic conclusion – that climate sensitivities significantly higher than the standard range (1.5 – 4.5ºC) were plausible – because there is significant other data, predominantly from paleo-climate, that pretty much rule those high numbers out (as we discussed again recently). The press coverage of the paper mostly picked up on the very high end sensitivities (up to 11ºC) and often confused the notion of an equilibirum sensitivity with an actual prediction for 2100 and this lead to some pretty way-out headlines. I think all involved would agree that this was not a big step forward in the public understanding of science.

Why did this happen? Is it because the scientists were being ‘alarmist’, or was it more related to a certain naivety in how public relations and the media work? And more importantly, what can scientists do to help ensure that media coverage is a fair reflection of their work?

A point that shouldn’t need repeating is that the media like a dramatic statement, and stories that say something is going to be worse than previously thought get more coverage than those which say it’s not going to be as bad. It’s not quite a fair comparison, but witness the difference in coverage for the recent Hegerl et al paper, which presented evidence that really high sensitivies are unlikely (a half dozen stories), and the Stainforth et al paper (hundreds of stories). (As an aside, a comment in the documentary that the recent Annan and Hargreaves paper was deliberately ignored by the media is without foundation – GRL is not Nature, and no press release was issued (a press release was issued – apologies). Expecting mainstream press coverage in such circumstances would be extremely optimistic).

Secondly, the scientists also need to appreciate that most journalists will only read the press release, and possibly only the first couple of paragraphs of the press release. Very, very few will read the whole paper. This implies that the press release itself is the biggest determinant of quality of the press coverage, and of course, the press release is generally not written directly by the scientists.

Thirdly, though we are trying to do something about it here, most journalists are not experienced enough in scientific topics to be able to place new results in context without outside help. Often they have a small number of preconceived frames into which they will place the story – common ones involve forecasts of possible disasters, conflict within the community (the more personal the better), plucky Galileos fighting the establishment, and of course anything that interacts directly with politics, or political interference with science. This can be helpful if the scientific story fits neatly into one the boxes, but can cause big problems if the story is either more complex or orthogonal to the obvious frames. Scientists are aware of this, but often are not pro-active enough in preventing obvious mis-framing. This implies that even if a press release is 100% scientifically accurate refection of the original paper, the press coverage can still be terrible.

So what went wrong with Stainforth et al paper? The press release is available here. The only science result in the press release refered to the 11ºC outlier but the release itself is not incorrect. However, both the title ‘Bleak first results…’ and the first paragraphs do not provide any context that would correctly lead a (relatively ignorant) journalist to appreciate that there was even a distribution function of climate sensitivities. I’m pretty sure that the point that was trying to be made was that relatively small tweaks to climate models can change the sensitivity a lot, and that you can’t rule out high sensitivities based on model results alone, but that was not clear for people who didn’t already know the context.

Myles Allen, for whom I have the utmost respect, I think made a rather poor argument in the BBC program. He stated that “if journalists embroider the press release without reference to the original paper, [the scientists] are not responsible for that”. I disagree. Looking at the press release, one could have predicted with high confidence that much of the coverage would focus solely on the 11ºC number and that they would assume that this was a new prediction. As scientists, I would argue that we have to take responsibility for how our work is portrayed – and if that means we need to provide better context, then we need to insist that that is included in the release. Myles is on much stronger ground when he argued that the mean model response (~3ºC sensitivity) wasn’t terribly interesting because it is just a reflection of the basic model they started with before any perturbations, which is true. However, without some statement about the relative likelihood of any of the high-end numbers, I find it hard to see how the journalists could have got the message right. Having said that, implications aired in the program that the scientists deliberately misled the journalists or said things that knew would be mis-understood are completely without foundation. (Update: Please see the response of the journalists listed in this comment below to really underline that).

What can we learn from this? The first and most fundamental lesson is that scientists should not relinquish control of the press releases. Public relations professionals are talented and useful when it comes to writing releases for media consumption, but the scientists have to be fully involved in the process. If there are obvious frames that the scientists want to avoid, they need to be specific within the press release what their results do not imply as well as what they might. A clear statement in the Stainforth et al release that placed the 11 C result in context of how unlikely it was and specifically stated that it wasn’t a prediction would have gone a long way to allay some of the worst coverage.

For an example of how this can work, the Solanki et al paper on solar sunspot reconstructions had a specific statement that their results did not contradict ideas of strong greenhouse warming in recent decades, neatly heading off simplistic (and erroneous) interpretations of their paper. On the other hand, much of the poor reporting related to the ‘methane from plants’ story could have been avoided if the authors had been more upfront in their release that their work was not related to greenhouse gas changes and had no significant implications for reforestation credits under Kyoto!

In summary, I would emphasise that the scientists and the actual papers discussed here and in the BBC documentary were not ‘alarmist’, however there is a clear danger that when these results get translated into media reports (and headlines) that scientifically unsupportable claims can be made. Scientists and the press professionals they work with, need to be very clear that, for the field as a whole, the widest possible coverage for any one paper should not be the only aim of a press release.

All publicity is not good publicity.

258 Responses to “How not to write a press release”

  1. 201
    Gary Braasch says:

    greetings from an admiring lurker; thanks for the information. My questions, the answers to which I may have missed in this string, are how can one relate the forcing at 2XCO2 to an expected atmospheric temperature rise in a way that a citizen can understand; and is the forcing as stated as a degree C to be compared with the forcing at 280 ppm (pre industrial) NOT with today’s measured temperature or rise above average? To put this another way, the forcing degrees measure something else than the reported increase in atmospheric temperature since pre-industrial times (which I believe from Hansen and others is .8 deg C), but what is the relationship stated for laymen? While I am at it, what is the beginning point in time for the .8 rise? Thanks. I think the IPCC did a disservice to themselves and us with the infamous range of temperatures for 2100, and it looks this time as if they are focusing on the 2x forcing plus more, but without a date attached.

    Many thanks to all.

    Gary Braasch

    [Response:Not quite sure what the question is. I think the best answer may be the “climate sensitivity”, which is the degree of warming expected (at equilibrium) when CO2 is doubled. The best answer to that is “about 3 oC” with a 95% confidence interval of about +/- 1.5 oC around that- William]

  2. 202

    Response to Remark #137, where Maureen Vilar stated: “A small number of models showed a slight drop in temperatures, particularly in phase 2. Of course these models had to be excluded from the final study – they did not represent pre-industrial climate accurately!â??

    According to the Stainforth et al. article, they used a grand ensemble of 2017 unique simulations. Out of 2017 runs, 869 simulations were ruled out as â??unstableâ??, which is 43% of all runs. The 1148 remaining (allegedly stable) runs represented 414 different models. That leaves that each model was judged by only 3 initial conditions. Few remarks and questions are in order:

    1. What is the criterion for correct representation of pre-industrial climate? How valid is the assumption that if the CO2-induced radiative forcing is artificially kept constant, the climate would not slide into an ice-ball anyway?

    [Response: The GCMs are written to start off stable, with no change in forcing. A GCM that wandered off into an ice age of its own wouldn’t be representative of the current, or recent past, climate, and would be no use – William]

    2. Actual initial conditions for the problem consist of temperature field, pressure field, moisture field, high cloud field, etc etc. Formally speaking, every such field has infinite dimensionality. For the computerized model, each field has at least the dimensionality of the grid in use, times the range of amplitudes at each grid node. This amounts to quite substantial number of variants of initial conditions. One would think that the set of 3 initial conditions per model does not represent the spectrum of all possible initial conditions very well.

    [Response:The atmospheric initial conditions don’t matter a lot – the system loses memory of these quickly (we all know that weather isn’t predictable, yes?). The oceanic initial conditions matter rather more (but these are actually slab models, no?, so they don’t have a deep ocean) but are supposed to represent the pre-ind conditions. There is no intent in the project to explore sensitivity to initial conditions – William]

    3. The deviations into cooler side were explained by complex interaction between heat flux, moisture buildup, etc in some spots of the globe, so the cool spot members were excluded. However, those cases were taken from the fundamentally-same model topology. What kind of analysis was done to identify if some inversed condition would occur, so some hot spots would emerge instead of cold spots, especially given quite limited coverage in initial conditions?

    [Response:Less sure about this. One of the criticisms of the study has indeed been that many of the high-sensitivity models may well have been unrealistic; the criteria for checking were weak – William]

    4. If only 3 initial conditions were tried to judge stability or instability of each model member, how one can conclude that the remaining thousands of variants would lead to same results (given the fact in #3), so that a seemingly stable model is in fact unstable and must be excluded as well?

    I think it is enough to conclude that predictions of the paper have little grounds for any practical certainty.

    [Response:Given that the study produces a large range, you’re pushing at an open door – thats exactly what they are saying (that a high sensitivity may well be possible). Others (James Annan for example) would say that observational constraints mean that sensitivities about 4.5 oC are very unlikely – William]

  3. 203
    James says:

    You guys did read everything I said about the prius. I did say in it’s FIRST iteration. The sencond set of cars is much more promising to me. (80/100MPG instead of 52MPG). And if you want to call it handwaving, then whatever, think of this, when the first hybrids came out (aka the prius) in 2003/2004 the MSRP for the prius was 22K versus a 13K corrolla. So you have to pay 9K more for a car that gets you 14 more MPG. Now I don’t know about you but even with today’s gas prices it is a little difficult to overcome that expense delta between the two. If you drive 200 miles a week, which takes 4 gallons of gas at $3. 52Weeks times 4 gallons times 3 dollars = $624 savings a year. It would require you to drive the car 10 years to get 2/3 of that savings back. If you double the mileage to 104MPG you still only save $1200!(What if you financed the car, then what?) How on earth do you think this is a feasible alternative? Whether or not the car costs more energy than it saves, (We have our differences in opinion, and quite frankly none of us are qualified to really argue about it one way or the other! Thus, if I am handwaving so are you unless you happen to work for toyota!) it simply is not a feasible option for 95% of the population that works hard for a living. When such options get similar in pricing you will see a higher uptake in interest from the everyday joe’s out there. Face it, until alternative energy cars can compete with similar classes of regular cars in price the mainstream public will not be very eager to buy them. (Either that or gas has to go up to 10 dollars a gallon.)

  4. 204
    Dan says:

    re: 204. The link to in post 201 regarding the new Prius and CO2 emissions in the development stage is not “hand-waving”.

  5. 205
    Eli Rabett says:

    187 redux. Sorry Gavin, unless I am very much mistaken there are a lot of tropical cyclones that never make to hurricane status, pushing a reasonable percentage of them over the limit would make an observable difference.

    [Response: You are correct. But detectability is a function of the signal to noise ratio – a small shift in the mean of a distribution can give a detectable signal at the tail but not a significant signal near the middle. – gavin]

  6. 206
    James says:

    Some folks have responded to my questions about alternative energy and I would like to engage in a little rebuttal.
    I am only trying to raise the issues of practicality to some folks heads as they are not technically grounded. (It is like me telling the climatologist how to model wind, as such don’t tell an eletrical engineer how to generate power!)
    Alternative forms to me are still not ready for prime time usage. (I can be corrected but please only someone who has actually worked in the power industry please!)
    Wind Power. Great but the power density per square foot of ground used is abysmal at best. On top of that you say screw the birds! Sorry we have ceased a lot of activities due to wildlife destruction. I am not a bird lover by any means but it is still an issue. Second, wind power is not readily available everywhere you would want it and it is unpredictable so it is not a constant or dependable source. Third, say it is possible to provide all of our power needs from wind power. What would we do to the world ecology? How would the earth’s ecology react to the extraction of that much power? What if the cure is worse than the disease? (I do not know this,I am only thinking out load here. However it is a reasonable line of thought, as we still don’t “know” enough about GW even though it is happening right now. How would we know the affects of something we have not tried yet?)

    Hydro is not green at all. (Contrary to popular belief!) It requirese massive land-use change and environmental damage. It also tends to make the stored water’s release Methane and CO2 due to the extra biomass destroyed by the dam’s head of water.

    Nuclear to me is the best alternative we have. It is here, it is mature, and it has great power density. And it requires the least effort on our part to make it happen as no new technology has to be invented. (Even with all of the negatives it has with spent fuel storage and lifetime.)

    Solar is also getting to be a good alternative, however unpredictability, power density, and also power storage and transportaion are problems here. (Still to me it is the best of the “renewable” sources.) I have also heard several people say put those things in the desert. Sure no problem, ever heard of sand storms and what they do to optical surfaces? Further not every country has a desert so are you going to run power lines from the Sahara to Europe? Lastly what will the affects be to Earth’s climate with the addition of hundreds of thousands to millions of hectares worth of Solar panels are installed?
    All I am doing is trying to convey as sense of reality here. Saying that we can depend on emergent sources of energy now and in the near future is like jumping on thin ice looking for a fish.

    Geothermal. A great source, however the issue with it is its availability. It is simply not an option for large areas of the earth as the geothermal heat is too deep within the crust at those locations. Also again what happens to earth when we extract vast amounts of power from it on an every increasing basis?

  7. 207
    James says:

    Re 205,

    To me it is handwaving, that is marketing slide and has no more “proof” than my statements. If toyota would illustrate those claims, then I am all ears. Until then it is handwaving.


  8. 208
    pat neuman says:

    re 193.

    Lewis, I don’t know how to reply to the many important points which you brought up. I’ll just say, … awhile ago, I read discussions from early 20th century Weather Bureau climatological data summaries. There seemed to be an openness to share information for the good of all, great attention to detail, little regard for self pride and no heavy desire to make money regardless of that’s just business. Climatological data was free to anyone.

  9. 209
    Adam says:

    Re William’s Responses to 196 & 202:

    196) Yes I initially thought that (especially after Ray’s responses about how to cut emissions) it might be of use for a sub-section, but also thought of possibly a “spin-off” site and now think that maybe better for a separate one. However it was worth suggesting here as I’m sure there are quialified people who read this site. A sort of “RealSolutions” as someone suggested on another thread.

    202) I think (and I apologise if I have this wrong) that Gary’s asking for a translation of what the climate sensitivity means in “real terms” as in actual temperatures by specific dates. The problem with that of course is that the answer is “It depends…” (though some of the variables are referred to in his question).

  10. 210
    Gary Braasch says:

    Thanks for the reply, William, at 202:

    “…. I think the best answer may be the “climate sensitivity”, which is the degree of warming expected (at equilibrium) when CO2 is doubled. The best answer to that is “about 3 oC” with a 95% confidence interval of about +/- 1.5 oC around that…”

    Yes,that is the currently accepted figure for doubling CO2 equivalent — does that number refer to warming from now til then (I don’t think so) or from pre-industrial or above the 20th Century average? Can it be compared with the measured warming up until now (above the average) of .8 C? Can one say “expected atmospheric mean temperature when we reach doubled CO2 is about 3 degrees higher than __________.”? I am trying to find a way to talk about this that folks can understand, so it needs to be accurate and have a comparison or starting point. Thanks.

  11. 211
    James Annan says:

    I can’t help but be impressed by how consistently the “godawful Metro” meme has been pushed by members of the cpdn team.

    In fact, the programme makers focussed exclusively on broadsheet coverage, quoting from (I believe) the Independent and Telegraph. This is the headline and first two sentences from Roger Highfield at the Telegraph:

    Screen saver weather trial predicts 10°C rise in British temperatures
    By Roger Highfield, Science Editor
    (Filed: 27/01/2005)

    Increased levels of greenhouse gases will have a much greater impact on climate change than previously thought and will lead to a “dramatically different” future, according to the largest ever climate change experiment.

    If the predicted levels of greenhouse gases predictions are reached, the ice caps are likely to have melted and Britain will be an average 10°C warmer.

    The Indy’s headline was “Global warming is twice as bad as previously thought”

    For readers from the outside of the UK, I think it’s fair to say that these papers are about as good as it gets, in terms of quality reporting.

    By all mean criticise the programme if you want, but criticise them for something they said, not something they didn’t say – especially as your criticism is mostly making claims of missed or misleading context!


  12. 212
    Gary Braasch says:

    I am making just another attempt to find a layman’s explanation about what climate sensitivity numbers can mean about future world temperatures. In the initial post, Gavin wrote that the articles “…confused the notion of an equilibirum sensitivity with an actual prediction for 2100…” Did you actually propose a correct way to explain what it means, Gavin? In my last post (211) I posited a phrase “expected atmospheric mean temperature when we reach doubled CO2 is about 3 degrees higher than __________.” in order to find out if this is a correct way to say it and to fill in the blank with a comparison. As I mentioned before, journalists and the public are going to jump at the highest number of any range of sensitivity so it would be good to be able to give it the correct interpretation.

    A follow on question (a tad impolite) is, if the sensitivity number is not a guide to possible future temperatures, and therefor policy planning (like a threshhold of dangerous interference per UNFCCC),what is it good for?

    Respectfully (really)


  13. 213
    James Annan says:


    The problems with associating sensitivity with a temperature in 2100 are twofold: first, at the time we reach CO2 doubling, the temperature will lag behind the equilibrium value due to thermal inertia, especially in the ocean (thought experiment – doubling CO2 today will not cause an instant 3C jump in temperatures, any more than turning your oven on heats it instantly to 450F), and secondly, the CO2 level we are at in 2100 depends on what we do between now and then anyway, and it may more than double, or not.

    Nevertheless, climate sensitivity is part of the puzzle, and it particularly matters if you are interested in stabilisation scenarios, since it indicates what a particular equilibrium CO2 level will mean for equilibrium climate. There is a good RC post on this here.

  14. 214
    Joel Shore says:

    Re #204 (james): You continue to slant your calculations against hybrids. It is simply not correct to compare the MSRP for a Prius and some base model Toyota Corolla. If you were to do that, why not ask why people pay much more for a Lexus than a Toyota Corolla (both non-hybrid models). You are comparing a car with much different features.

    When Consumer Reports did their comparison, they compared to the Corolla LE and got a price differential of $5700 (and this was even after taking into account the market reality that you could buy the Corolla for below the MSRP but would pay the MSRP for the Prius). On the Prius messageboard that I sometimes go to, people were arguing that this comparison was still unfair as the Corolla LE still is not equivalent in room or features to a Prius…But, it is at least a little bit more in the ballpark than your estimate!

    Of course, whether the Prius pays for itself in the current market uncorrected for externalities is a different question than whether it would pay for itself once you accounted for the price of gas if it included all the environmental costs and much of the cost of the Iraq War (which, even if not directly about oil, is really pretty much about oil in the sense that it is what makes that whole region of important strategic interest to us).

  15. 215
    Joel Shore says:


    On a larger level, it is common in science to break up a big problem into smaller problems. This is particularly important if this helps isolate very different aspects of the question. The whole problem of how much warming will occur convolves lots of questions involving how the climate reacts to greenhouse gases, the carbon cycle, and our future path as societies in terms of our energy use (and other emissions). It is useful to break these apart by asking a question specifically regarding the climate system: What is the climate’s sensitivity to a given change in CO2?

    One can then separately address the issue of what levels of CO2 we are likely to actually reach, a question that involves understanding the possible future course of society (complicated by the fact that our future course will be influenced by our understanding of this and other environmental problems!) and, to a lesser effect, some issues involving the carbon cycle such as how the ocean’s uptake of CO2 will evolve over time and to what extent melting in the polar regions will release additional CO2 (and methane) as they warm.

    Unfortunately, the general public and the media often don’t understand this division and end up muddling things together…thinking of the climate sensitivity number as predicting the actual warming. Fortunately, since a doubling of CO2 from pre-industrial levels by 2100 is at least in the ballpark of expectations, the error they introduce by doing this isn’t too huge. However, it is important to keep in mind that we might easily more than double it if we really don’t make much effort to cut back (I think the current estimated reserves of fossil fuels would increase CO2 by a factor of like 5 or 10, which would mean a warming of roughly 2-3 times the climate sensitivity for doubling CO2 [because of the logarithmic dependence of the resulting warming to CO2 levels])…and CO2 levels may be able to fall short of doubling if we really make a very strong effort to reduce emissions.

  16. 216
    Grant says:

    Re: #213

    Gary, I think you’re looking for a simple layman’s explanation. I’ll try, but I’m not a climate scientist, so if I get it wrong, moderators please correct me.

    “Sensitivity” means the total equilibrium rise in temperature due to doubling CO2. That means that if we raise CO2 to double *pre-industrial* levels, then the expected equilibrium temperature increase will be about 3 deg.C above *pre-industrial* temperature. Doubling it again (4x pre-industrial) will raise another 3 deg.C, doubling yet again (8x pre-industrial) yet another 3 deg. C. That’s assuming that sensitivity is 3 deg.C.

    It’s quite correct that there’s a lot of thermal inertia in the system, so we won’t see all that increase right away. But, it’ll be *in store* for us. Anyone care to estimate the lag time for global temperature response? Also, we don’t know that the sensitivity is 3 deg.C; that’s kinda what the whole thread is about!

  17. 217
    david Iles says:

    I have spent some time this morning reading this blog and the comments associated with it. I have to admit i only got to #57. But what seems the most pressing to me, are the effects, of even a 2C rise in global temperatures. Wouldn’t that bring about massive famine all around the equator and raise the ocean levels sufficiently to inundate many cities? It would probably have an extreme drying effect on many ecosystems thereby changing them significantly. It would surly dry out the already unthawed tundra in Siberia and Alaska, which would add a very significant methane load to the environment. And would likely dry forests to the extent that fires would be widespread and also release massive amounts of green house gases. It would probably make our whether more erratic and thereby make agriculture much more difficult. We are seeing a pretty substation effects by just a 1-11/2 degree of warming. If you want to alarm the puplic into action wouldn’t that be the place to start.

  18. 218
    Gary Braasch says:

    Thanks for the explanations about 2xCO2 sensitivity. It is not a simple thing to explain, but the oven idea is good as is the general idea that by pointing out this relationship, you are encouraging people to consider if continuing to add CO2 and other GHGs is prudent or not. Since the post that James Annan referred to (31 Jan 2006 Can 2°C warming be avoided?) uses a cat in the oven analogy, and the real temperature at 2xCO2 will depend on whether people change their behavior in ways we really can’t predict from this viewpoint, then the cat in that oven must belong to Schrodinger. I prefer the frog in a pot analogy myself, if we must resort to torturing animals to make our points. Gary

  19. 219
    David B. Benson says:

    Re #217: Time lag for global temperature response. I’m not a climatologist, but I’ve read 3 books on climatology. Looking at W.F. Ruddiman’s “Earth’s Climate: past and future” you will find his graphs of future global temperature response. As best I recall, it’ll take about 200 years to peak and about 2000 years to completely restabilize, returning to the usual state of quasi-equilibrium.

  20. 220
    Hank Roberts says:

    Morgan, you’re demomstrating pre-technological thinking when you imagine that physics and chemistry and electronics can support human life without the rest of the environment. Look up ‘ecosystem services’ for references. Most of what’s being provided ‘free’ is from life on earth, starting with the oxygen in the atmosphere.

  21. 221

    Re #220: “it’ll take about 200 years to peak and about 2000 years to completely restabilize, returning to the usual state of quasi-equilibrium.”

    Why do people assume that the “usual state” of climate system is “quasi-equilibrium”? One would submit that multitude of large de-glaciation swings followed by bumpy relaxation into ice ages rules this assumption completely out, unless you have a very special emphasis on “quasi”. One would think that these huge historical variations are rather signs of a system that is very far from equilibrium, in which case the usual “sensitivity” technique is not adequate and may be misleading.

  22. 222
    David B. Benson says:

    Alexi, maybe ‘quasi-equilibrium’ is the wrong term. How about ‘tracking orbital forcings’? The ice core records seem to me to be in good, although far from perfect, agreement with orbital forcings at the approximately 41,000 and 26,000 years quasi-cycles. The roughly 100,000 year scale interglacials remain a mystery, at least to me. In any case, all these time scales are much longer than the 2 to 20 centuries I mentioned.

    Have you read Ruddiman’s book? How about Oldfield’s?

  23. 223
    Coby says:

    I think 2000 year predictions are pretty problematic. That said, I’ll make one. Soon we will have begun an irreversible melting of the Greenland icesheet and if that happens that will have very significant effects on the climate, well pretty much indefinately.

    Aslo, regarding climate sensitivity a very key thing to remember, especially if sensitivity turns out to be on the high side, is that the “final” equilibrium temperature (Alexi’s concerns about there being such a thing aside) calculated from climate sensitivity does not take into account carbon cycle feedbacks OR ice sheet changes.

    We lay people tend to thing 2x CO2 means doubled by us. Doubled by us may in fact result in more than doubled CO2.

  24. 224

    David, re #222? “tracking orbital forcings”

    The theory of direct orbital forcing is obvously incorrect, since integral of insolation does not change for more than 0.1% during eccentiricity variations. More, there does not seem to be any fromally-identifiable cyclicity at all. For example, the following paper
    finds that deep-sea and ice core records are formally indistinguishable from stochastic data even if the data are artificially tuned to Milankovitch cycles.

    The other theories of “amplification” rely on some sort of near-unstable undelying system with rich potential for internal dynamics, which must be also far from equilibrium to swing that wide while being well-bounded at the same time.

    People ususlly argue that reality usually follow the simplest possible rule. They are right – self-sustained chaotic oscillations _are_ the simplest explanation of the observed facts, with maybe some inclusion of well-known effect of frequency sysncronization in non-autonomous systems.

    [Response: Saying “self-sustained chaotic oscillations” doesn’t really say anything. The key is in getting down the physics that would give you such “self-sustained chaotic oscillations.” There is actually a great deal of work that has been done on this subject, but you shouldn’t dismiss all the orbital forcing work without taking time to look at what has been done. There’s a great deal of it, which goes beyond your cavalier dismissal. For example, the high-frequency precessional signal is actually a very,very large forcing, peak to peak. There is a modulation of the envelope of this by the eccentricity cycle. What you need to get ice ages out of that is just a rectifier. That’s where your nonlinearities come in. If you think that there is a self-sustained ice-climate oscillator that works without that kind of excitiation, by all means write one down and go publish it. You’ll be famous. –raypierre]

  25. 225
    David B. Benson says:

    Coby and Alexi, I am going to offer a much simplier, highly studied, and reasonably well understood system only by way of analogy. Alexi needs to understand that this system is, in nontrivial detail, nonlinear. This system is the power grid. The system must continually be stablized to maintain 60 Hertz AC electricity and between 110 and 125 VAC. The power grid has essentially no internal storage capacity, being best thought of the method to move electrical power from the producers to the consumers. At each moment in time the electic power consumed is equal to that produced. This follows from Kirkhoff’s laws.

    The power system is always at some operating point, but this operating point is continually changing as demand changes. Demand changes on an hourly, daily and yearly basis. In response to this change, producers go on-line or off-line or vary the amount of power supplied.

    I suppose that Alexi, in looking at a graph of the power supplied versus time for the Western Power Grid, will see chaos. Others will see responses to needs, without necessarily fully understanding the changes in demand.

    Coby will see the change in operating point as a ‘significant effect’. For the power companies this is true. Some possible operating points are more efficient for some producers.

    Both Alexi and Coby will appreciate that the fundamental equations to be solved to determine the operating point for the next 15 minutes do not always have solutions.
    None at all. Power engineers have to live with this and attempt to make approximations and quick adjustments.

    The main point is that here is a system of power flows which ‘chaotically’ oscillates in rather poorly understood ways. Nonetheless, when was the last time you were without electric power for more than 2 hours?

    Only an analogy, but I hope it helps.

  26. 226
    James says:

    Re 225.

    No not really. Yes the supply and demand of power are always changing but the basic operating prinicple of the system is well understood. IMHO that is not so with climate science. The overall science is not near as mature, and right now every answer they have raises more questions.

  27. 227
    Hank Roberts says:

    The electric power grid is one place US political deregulation fell flat on its face. Even before the predictable gaming of the payment system by marketers, it failed because politicians don’t understand physics and mandated a regulatory system that violated physical law. Nature responded accordingly.

    With new solar flare season coming on, the problems will be showing up again soon. Can we do better with climate?

    While this is a rather old cite, it’s one good place to start:

    “Experts widely agree that such failures of the power-transmission system are a nearly unavoidable product of a collision between the physics of the system and the economic rules that now regulate it.”

    Look ahead to the next generation of coal-fired electric power plants. Raypierre makes the case very clear in the current Chicago Int’l Law J. that closed system combustion with oxygen can avoid much of the externalization of costs built into current plants; I imagine it can even contain the uranium and thorium fallout from coal (which is worse than that from a properly operated fission plant).

    Can we do this sort of thing right?

  28. 228

    Re #206 and “Geothermal. A great source, however the issue with it is its availability. It is simply not an option for large areas of the earth as the geothermal heat is too deep within the crust at those locations. Also again what happens to earth when we extract vast amounts of power from it on an every increasing basis?”

    1. The most commonly used type of geothermal generator relies on local sources. There is, however, something called “Hot Dry Rock Geothermal” which can be used nearly anywhere.

    2. Human power needs are orders of magnitude less than world geothermal flux.

    3. As I said before, all methods of generating energy have bad side effects, but they do not have EQUALLY bad side effects. Solar, wind, geothermal, ocean thermal and biomass seem to me to be relatively good sources, whereas fossil fuels and nuclear do not. Windmills may kill birds, but at least they don’t allow many critical masses of plutonium to mysteriously disappear from inventory.

  29. 229
    Gar Lipow says:

    Re 206: Plenty of electrical enegineers on both sides of this issue. In terms of wind – it can provide at least 20% of grid without storage; that is also well documenedt. It can provide more with small amounts of storage – provide 2 hours of nameplate capacity which equals 6 hours of average output and wind can provide around half of consumption.

    In terms of problem that we can’t always generate what we need where we need it – that is what power lines are for. Italy is looking at importing power from North African desert, France is considering importanting hydroelectricity from the wetter parts of Africa. We do know how to move power long distances.

    In terms of greeness – Wind kills fewer birds than any other power measure. Put it this way; if wind were to provide 100% of U.S. electricity (not practical for stability reasons but assume it as a way of measuring consequences) it would kill around 1 million birds a year with 1980 technology, probably a lot less with today’s wind gernators. By contrast feral cats in the U.S. kill 100 million birds per year. Cell phone towers and tall building kill – I forget the number, but same number of zeros. Overall human activity kills at least half a million birds per year in the U.S.

    In terms of dams, I agree that dams are not ecologically sound. But the thing is we have to build them for other reasons besides power anyway – water supply and flood control. Incrementally, how many fewer dams would you build if all power came from other sources, so long as those needs remain?

    In terms of mirrors and such getting scratched – you put up covers during dust storms. We’ve managed to keep solar thermal plants operating since the the mid-80s in the Arizona desert. Maintenance is one of the reasons solar thermal is 11 cents per kWh without storage; not just capital costs (though those are high). Solar thermal O&M is higher than wind power (though still lower than fueled plants).

  30. 230
    Hank Roberts says:

    Good example here of how reading the actual article, vs. reading only the press release, informs comments

  31. 231
    Morgan says:

    Response to 220. I think your conception of nature is too limited. There are at least two and probably many many more earthlike planets. Even relatively nearby in the milky way galaxy.

  32. 232
    Hank Roberts says:

    >231– “There are at least two and probably many many more earthlike planets.”

    Morgan, would you provide a link to at least the press release, and if possible the journal article supporting this statement? I’d like to compare them and see if I understand them the same way you do.

    To elaborate on the link I posted — this is one of the editors of Reason Magazine, who has changed his mind about warming; the thread below his posting includes comments from some people who read only his posting, some who read the press release, and one or two who actually read the science on which he based his change of mind. Their responses are from all bases, some purely political/ideological, some thinking about the science.

    It’s a contemporary example of intellectual honesty at work — and I do mean work, thinking about science is hard for everyone, and thinking despite one’s political assumptions is harder yet.

    The thread is already a very good illustration of why reading beyond press releases is important for understanding.

  33. 233
    David B. Benson says:

    Re #231: Morgan, I opine not. Have you read “Rare Earth”?

  34. 234
    Don Baccus says:

    ‘In terms of greeness – Wind kills fewer birds than any other power measure. Put it this way; if wind were to provide 100% of U.S. electricity (not practical for stability reasons but assume it as a way of measuring consequences) it would kill around 1 million birds a year with 1980 technology, probably a lot less with today’s wind gernators. By contrast feral cats in the U.S. kill 100 million birds per year.’

    I *hate* that comparison, even though the wind power people trumpet it constantly.

    For it presumes that killing a species at risk such as the golden eagle is equivalent to a cat killing a house sparrow.

    That argument could be used by the timber industry to justify liquidating the northern spotted owl. There are only a couple thousand breeding pair in the pacific northwest, say on the order of 10,000 individuals alive at any one point in time (numbers flucuate greatly both by year and season).

    So by that argument, the timber industry can say “killing 10,000 spotted owl is nothing, after all cats kill 100 million birds each and every year!”

    Good grief.

    Side note regarding Gary Braasch. He’s a REALLY GOOD photographer. Internationally renowned. Check it out.

    Note that one of his photos graced cover of the November 17, 2005 issue of Nature, the one that said “Climate Change” in impressively large type.

    OK, Gary, you’ve been outed :) Gotta boost the rep of a fellow Oregonian. Glad to see you’re reading Real Climate.

  35. 235
    Don Baccus says:

    “Response to 220. I think your conception of nature is too limited. There are at least two and probably many many more earthlike planets. Even relatively nearby in the milky way galaxy.”

    How is this going to help us in the next century or two?

    “relatively nearby” in relationship to what? Portions of the universe that are even more unreachable than planets in our galaxy? Boy, that’s useful.

  36. 236
    Richard K says:

    re: demonstrating the greenhouse effect using a ‘homemade’ glass box (comment #119 and responses)

    My organization, the Yale Project on Climate Change, is keenly interested in finding a model that can be used in classrooms to demonstrate the greenhouse effect (using physical objects, glass, metal, whatever – not a computer simulation). Can anyone point me to one?

    The comments in this thread suggest that such a model is not possible, although some surrogates are mentioned in comment #150.

    We hope to find something that will appear more literally, directly analogous to the greenhouse effect to lay audiences, say, at high-school level, than the experiments mentioned above. I stress the words “appear” and “lay audiences” in that sentence.

    For example, having water level in a bucket represent temperature works at a level of abstraction that my university teaching experience suggests is unlikely to be found in individuals without a college-level physical science background.

    I’m not yet convinced that such a model is a physical impossibility. It may require some highly creative and original thinking, and it may not be something that gets its creator published in Science, but I’m not ready to give up: the benefits of having something tangible to present to people would be enormous.

  37. 237
    Hank Roberts says:

    Richard, several people have pointed out that the total amount of CO2 in the preindustrial atmosphere, if it were all at ground level, would be five feet deep. Double that and you’d get ten feet. Raypierre pointed out that a simple photoelectric cell sensitive to the long-wavelength infrared can be used to measure how much IR gets through a column of gas (attach the output to a voltmeter). An infrared camera would perhaps also work, if you get the right wavelengths.

    So you could take a five foot pipe and cover both ends with IR-transparent plastic, fill it with CO2, measure how much IR passes through it (maybe even using sunlight as your source, with an infrared filter). Then do the same with a ten foot pipe. Comparison would be, very roughly, the difference between preindustrial CO2 and 2x that.

    I’m making this up, but there seems serious interest in actually showing people the effect.

    Alternatively, can you get a sky map/photograph taken in the infrared from a satellite, and compare that to a sky map taken from the ground? Most of the far-red/infrared stars should look very different through the atmosphere, to the extent it doesn’t transmit those wavelengths.

    Maybe a simple ‘infrared security camera’ or even an infrared photoelectric security beam device, or an infrared TV remote control, would demonstrate the difference between 5 feet and 10 feet of CO2.

    [Response: The device I was talking about wasn’t quite a “simple photocell,” but was a low-tech pyranometer, with a linear response between infrared flux and current. We bought these for our global warming lab, and they’re used in many physics departments for experiments with blackbody radiation. I think they cost around $50 to $100, but it would be interesting to know if something could be hacked up from a cheap infrared detector of the sort used in remote control systems. It’s certainly true that you should be able to measure the difference in IR absorption between a 2m and 4m column of CO2 with such a device. HOWEVER, note that you won’t really be illustrating the greenhouse effect as it works on a planet, since that depends on the difference in temperature between the ground and the upper atmosphere. The outgoing longwave radiation is composed not just of the radiation that leaks through to the top from the warm lower layers, but also of the “cold” radiation emitted from the upper atmosphere. If you take a tube of CO2 at 300K, and you illuminate it with a 300K infrared source, you’lll still see 300K radiation coming out the end of the tube, no matter how much CO2 is in there. I guess if you have CO2 at room temperature (around 300K) and illuminate it with a really hot source (maybe 600K), you’d get some sense of the effect of the “hot” radiation going in one end being replaced by “cold” radiation coming out the other. You could also have a lot of fun squirting some methane or HFC’s into the tube to see what happens. Note that a 2m tube of CO2 at 1 atmosphere pressure will be somewhat more absorptive than the same amount of CO2 spread over the depth of the atmosphere, since high pressure increases absorption. –raypierre]

  38. 238
    Grant says:

    Re: #236

    Here’s an idea. I don’t know whether or not it’ll work.

    Start with a model “earth” — a thin, hollow sphere (so it takes very little energy to change its temperature). Paint it black.

    Enclose it in a glass sphere. Attach it by hanging it by a thread from the top of the enclosing sphere. Choose a thread with the lowest possible thermal conductivity, and make sure the model earth doesn’t touch the enclosing sphere. Pump all the air out of the enclosing sphere. This will reduce heat loss from conduction and convection.

    Enclose the “enclosing sphere” in a big glass box. Pump in a greenhouse gas. *Don’t* use CO2 — it’s not as effective a greenhouse gas as other choices. CH4 is 24x more effective (per molecule), CFCs are 10-20 thousand times more effective.


  39. 239
    Hank Roberts says:

    See 150 for Raypierre’s suggested demonstration.

  40. 240
  41. 241
    Hank Roberts says:

    Well, I think those are all good examples of press releases that require reading the whole press release, at least, to understand. The headlines say “Earthlike” and the text says this means “rocky, not a gas giant” — for example, 7.5x Earth’s mass, 200-400 degrees Centigrade is Earthlike. But not like Earth.

  42. 242
    Gar Lipow says:

    RE: 234. And if we were talking about continuing to kill raptors you would be justified. But the bird problem has been solved. We now know how to locate generators so they kill many fewer creatures and also locate them where they won’t kill raptors. Incidentally how does rebutting a common libel against wind make you a ‘wind person’. The Sierra Club, Greenpeace, NRDC and the Audobon society all support wind – including the wind farm off Cape Cod. Sounds like a pretty green power source to me.

  43. 243

    re comment 236

    Richard, I’ve used the leaky bucket analogy in schools, and it generally seems to be understood – as long as they’re old enough to have covered the fact that pressure in a liquid increases with depth.
    There’s some other stuff on our website ( – teaching resources) in particular an experiment with a bottle of carbon dioxide (under key stage 3/4 science) which might be of interest.

  44. 244
    Don Baccus says:

    RE 242: “And if we were talking about continuing to kill raptors you would be justified. But the bird problem has been solved. We now know how to locate generators so they kill many fewer creatures and also locate them where they won’t kill raptors. Incidentally how does rebutting a common libel against wind make you a ‘wind person’. The Sierra Club, Greenpeace, NRDC and the Audobon society all support wind – including the wind farm off Cape Cod. Sounds like a pretty green power source to me.”

    If you read my earlier posts on wind power, you’ll learn that I support wind power and am aware that siting and turbine design issues have largely been solved.

    That doesn’t save the really, really stupid argument made by wind power advocates that “cats kill more birds than wind turbines”.

    That really is a timber industry-style argument you’ve got going there.

    Given the resistance some in the industry have had in the past towards implementing the monitoring and site evaluation protocols that lessen the impact, it’s a great way to trigger a knee-jerk “the industry’s full of it” reaction among those who are potential allies.

    If you’re comfortable with it, don’t complain when people react negatively to windfarm proposals.

    And, yes, I know the Audubon society supports wind power. I sat on the board of the 2nd largest chapter in the country for 15 years, after all.

    I also remember our being called “anti-environment” in the press by wind power advocates for demanding raptor surveys of a proposed windfarm site in the Columbia Gorge known to be frequently used by golden eagles (a species of concern) and peregrine falcons (listed).

    [Response: Okey doke; let’s agree that windpower is a good thing, generally, that it’s desirable that engineering solutions be sought to (further) minimize and certainly monitor the effect on bird life — especially raptors — and that the “cats kill more birds than wind turbines” argument isn’t a stellar example of a well-reasoned scientific argument addressing a legit scientific concern. Now let’s please move on from this. I note that a lot of the discussion here has moved away from the subject of press releases, but it’s been for the most part interesting and substantive, so I’m inclined to let it go on for a while longer before closing the comment form. –raypierre]

  45. 245
    Dan Allan says:

    Re 236, demonstrating the greenhouse effect:

    What if your tube of CO2 were divided by a piece of plastic into two sections – the “upper atmosphere” component and the “lower atmosphere” component, and the lower atmosphere segment were heated or the upper atmosphere segment cooled before shining an IR source vertically down the tube? The two sections are mixed afterward by removing the plastic and a temperature taken. Wuld this result in a GH effect due to more IR bouncing off the cooler “upper atmosphere”? The same process could then be repeated, with the same initial temperatures, for an air mixture containing less CO2. Would the resulting temperature inside the tube end up cooler?

    [Response: Not bouncing, not bouncing, please! Infrared doesn’t bounce off of CO2 in the usual gaseous greenhouse effect. Infrared is absorbed by CO2, and re-emitted at the temperature of the CO2 doing the absorbing. (There is an exotic scattering greenhouse effect that may work with dry ice clouds on ancient Mars, but that’s another matter, not related to global warming on Earth) But yes, if you could somehow maintain a temperature gradient in the tube it would be a bit like the actual greenhouse effect. Note that since you don’t have any significant compression effect in a short tube, you’d have to do the experiment “upside down,” i.e. with the cold CO2 at the bottom instead of at the top. Otherwise, the cold CO2 would just sink and mix with the hot CO2 at the bottom. –raypierre]

  46. 246
    Hank Roberts says:

    This is getting informative!

    You could, perhaps, get a ‘compression effect’ — need a sanity check here, please — by spinning the tube (like a spoke on a wheel, attached at one end). Near the center it would have no added “weight” and as you move out toward the distal end each molecule would have more centrifugal ‘weight’ added, so be denser.

    Hmmm, how narrow a tube would you need to defeat rapid mixing by diffusion, if possible at all?

    Anyhow taking off on the prior suggestion of a membrane to set up:

    Put the cold gas toward the center, the hot gas toward the end, separated by a membrane; spin the thing up to where you have a density gradient from center to end (sufficient to hold the hot gas at the ‘heavy’ end?); remove the membrane (or would you even need to remove a membrane if it were transparent to IR?)

    Of course a centrifuge spinning a ten foot tube fast enough to make a density gradient in the contained gas would be a potential ballistic launcher in the the “kids, don’t try this at home” category.

    All in all Raypierre’s suggestion of doing the experiment ‘upside down’ makes more sense and would be a lot simpler, I think. Oh well.

    [Response: This has the makings of a cute exam problem. How fast a centrifuge would you need to make this work? As a rough estimate, let’s say we want a 10K temperature variation from the dry adiabatic lapse rate in a 2m column. The dry adiabatic lapse rate is g/cp, where g is the acceleration of gravity and cp is the specific heat at constant pressure. For CO2, that’s about 12K per kilometer for 1 Earth g. Therefore, to get the desired temperature variation over 2m, you’d need a centrifuge that got you up to about 500 Earth g’s. Don’t count on riding along in the thing while you’re making your infrared measurements! –raypierre]

  47. 247
    Hank Roberts says:

    >246 comment
    I know little laboratory desktop centrifuges reach 500g — a centrifuge 4 meters in diameter to produce 500 g at the rim? The flywheel energy storage people have the math for it:

  48. 248
    pat neuman says:

    A press release by the U.S. CCSP is at:

    In How not to write a press release, Gavin wrote:
    … the scientists also need to appreciate that most journalists will only read the press release, … This implies that the press release itself is the biggest determinant of quality of the press coverage …

    In the last day or two, comments (104, … 122, 128, 130, … ) have been posted at under RC .. A Mistake with Repercussions.

    I would like to see comment from others about the 02 May 2006 at

    Is that a good example of How, or how not, to write a press release?

  49. 249
    llewelly says:

    Pat, about that press release:

    According to the published report, there is no longer a discrepancy in the rate of global average temperature increase for the surface compared with higher levels in the atmosphere. This discrepancy had previously been used to challenge the validity of climate models used to detect and attribute the causes of observed climate change. This is an important revision to and update of the conclusions of earlier reports from the U.S. National Research Council and the Intergovernmental Panel on Climate Change.

    I think this is a reasonable summary.

  50. 250
    Gar Lipow says:

    >Okey doke; let’s agree that windpower is a good thing, generally, that it’s desirable that engineering solutions be sought to (further) minimize and certainly monitor the effect on bird life — especially raptors — and that the “cats kill more birds than wind turbines” argument isn’t a stellar example of a well-reasoned scientific argument addressing a legit scientific concern.

    This actually ties back to the question of press releases. To what extent is it reasonable to answer the question asked rather than try to read the questioners mind? Quite often people make the argument “wind kills birds”. The cat argument is a quite legit answer to that question. There are three reasons for phrasing the question this way – ignorance (in which case someone really believes that sheer number of birds is the problem and the cat comparison is reasonable), sloppy phrasing (in which case the cat comparison is a reasonable way to avoid the other person inadvertantly misleading readers) or deliberate dishonesty (in which case the cat comparison is again a legit way to prevent deliberate misleading). In short if you want the raptor issue dealt with bring up the raptor issue. If, inadvertantly or deliberately, somebody misleadingly implies that wind is a problem for sheer number of birds killed, then it is reasonable to put that number into perspective by comparing other things that kill much larger numbers of birds. In point of fact this sort of comparison is the only way to rebut that particular phrasing. If you don’t like cats, we can use cell phones, coal smokestack, tall buildings, agriculture, automobiles. But it is quite true that wind kills large number of birds; just many fewer than other things that kill large number of birds. If someone brings up birds in general, rather than raptors that is a reasonable way of to rebut them.

    This is likely to come up in global warming science as well. Sooner or later someone will do a study refuting a really dishonest or sloppy argument X. And global warming deniers will cry out at the attack on this weak sloppy argument; “how horrible; you are ignoring Y” they will cry. And the answer will be , I think , the same as I just made – if you want a reply to the stronger argument, make the stronger argument. If someone advances a sloppy argument then it needs to be rebutted to prevent it misleading others.

    I do think in the future I will also bring up raptors to keep it in perspective as in “no environmental group worries about sheer number of birds killed” followed by a comparison to put raw numbers into perspective “many do worry about poorly sited wind generators killing endangered birds, especially raptors” tell the story of Altamont farm and the proposed Exxon farm which was quite properly stopped. “However the modern wind industry knows how to avoid these problems so long as their feet are held to the fire to ensure they carry out mitigating measure such as proper location, proper siting, proper spacing, slow moving easily visible blades, towers that don’t make good nesting sites to attract birds and so on.” I think if you know an objection is a mistatement of another objection, it is still neccesary to rebut the mistatement, but then move on to the real argument and rebut it too.

    Don’t know whether this can carry forward to press releases for global warming studies. I suppose it can in the sense that you can say that “Study A fails to find any support for hypothesis X. It does not however deal with hypothesis Y which which Study B found no evidence for.”