Goodbye to all that

This post announces my (William Connolley’s) departure from RealClimate, and indeed from the professional climate field in general, in favour of the wide world of Cambridge software engineering. I’ve enjoyed my time with (Real)Climate, but now its time to move on.

Normally the career change of one minor scientist would be of little interest to the outside world, and perhaps this one will be too, but the climate arena does get rather highly charged. So perhaps a few words of explanation are in order.

This doesn’t represent any disenchantment on my part with the state of the science, or with IPCC, or with RealClimate – all of which continue to have my respect. I’m sure that RealClimate will continue to deserve its high reputation as a source of accessible explanation and comment on important climate issues. It’s more a reverse of that – in some senses, much of the main areas of climate science have now become much clearer than when I began to be interested; the obstacles to progress are now very obviously political not scientific.

I expect to continue my (now amateur) interest in climate; my pet blog will remain at least for a while – feel free to join me there.

130 comments on this post.
  1. Ray Ladbury:

    Jim Cripwell, Well, thank you for your your fascinating thoughts on the scientific method. [edit]
    However, that was not what I asked. Those who actually understand science find the mountains of evidence quite convincing–as evidenced by the fact that not a single professional society of scientists now dissents from the scientific consensus on what is causing the current warming epoch. What I asked is what evidence it would take to convince YOU. If YOU cannot name an experiment that can be accomplished that would convince YOU, you are saying climate science (as well as Geology, Astronomy, Paleontology…) cannot be science. Yet the success of the field belies your assertion.
    Oh, and by the way, we can measure forcing–the difference between the energy radiated from Earth and captured by CO2 and the amount finally radiated away by the much cooler upper atmosphere. We also deal just fine with water vapor, despite its variability.
    Science works, Jim. And it doesn’t have to take place in a test tube to be science.

  2. John Mashey:

    re: #99 Gavin
    Your patience is amazing.

    As I once pointed out in here in July, Cripwell thought Kristen Byrnes’ “ponderthemaunder” so credible to publicize it around bulletin boards where it was *rather* off-topic :-)

    “Her” latest effort, dated today, concludes:

    “The comparrison of this data is compelling evidence that increasing atmospheric CO2 does not cause global warming.”

    [Response: Oh good. We can all go home then. – gavin]

  3. Philippe Chantreau:

    Correction: on that post 96, I meant tropopause changes rather than tropospheric

  4. Ron Taylor:

    Re 99 Gavin, it is good to know that you are not going to continue to waste time trying to respond to the nonsense that Jim keeps posting. I hope Ray and others will follow your example. This post in particular is simply gibberish. He is cluttering up the threads with this stuff, making it difficult to maintain a coherent flow of information and (rational) ideas. You have been more than patient and enough is enough.

  5. Ray Ladbury:

    John Mashey,
    Jim serves a vital purpose here–reminding us that the denialophere is alive and well, and that they not only are not evidence based, they don’t even know what constitutes evidence.

  6. Timothy Chase:

    Re Philippe Chantreau (#96, #103)

    I agree on both counts…

    There is a variety of evidence which the view that greenhouse gases are currently the single greatest forcing of the climate system explains which other views would find difficult or impossible to explain, either qualitatively or quantitatively.

    1. Polar amplification – the poles warm more quickly than the more equatorial latitudes;
    2. The cooling of the stratosphere;
    3. The fact that winter has shown a greater warming trend than other seasons;
    4. The fact that nights have warmed more quickly than days;
    5. The duration and timing of the warming – given the fact that other forcings are typically cyclic or flat — when the greatest correlation of a forcing to the trend in temperature is roughly at the ten-year;
    6. The rise in the tropopause; and,
    7. The expansion of the Hadley cells.


    More importantly, our understanding that greenhouse gases are the greatest driver responsible for the trend towards higher temperatures and that they have been so for quite some time isn’t simply a matter of the evidence but of well-established physics. If one were to find an alternative explanation of all the above evidence, one would also have to explain why greenhouse gases weren’t having this effect — given that physics shows they must. And this would be made all the more difficult insofar as we are able to take satellite measurements of their emissions over many different altitudes on over 2000 different channels.

    Of course, one might attempt such an explanation of the inefficacy of greenhouse gases in terms of, for example, the reduced formation of clouds resulting in negative feedback to greenhouse gases. But then one would have to be able to show why this negative feedback does not occur in the case of the forcing (e.g., solar insolation) that one is proposing as the alternative major forcing.

    Greater positive feedback for one forcing typically implies greater positive feedback for other forcings. Likewise, greater negative feedback for one forcing typically implies greater negative feedback for other forcings. And the paleoclimate record strongly suggests that climate sensitivity of 2.8 K per CO2-doubling is correct, but if there is any substantial error in this, we are far more likely to be underestimating the sensitivity rather than overestimating it.

  7. Jim Eager:

    Re RomanM @ 98: “I raised the cloud issue whose possible ramifications on temperatures by varying the amount of solar insolation reaching the earth’s surface, IMO, do not need a “theory”, even though the causes for the formation of those clouds at present do not seem to be well understood, as an example of a reasonable possibility which seems to be a counterpoint to the posters I refer to above.”

    But that would assume that clouds are a net positive forcing. As Gavin and others have pointed out, repeatedly, clouds have both a positive forcing (insulating and radiative) and a negative forcing (higher albedo) at the same time. The net forcing would be the excess beyond cancelation of these opposed forcings. It is premature to conclude even what sign the net has, let alone its magnitude.

    RomanM: “It won’t “negate the physics”, but if such forcings exist, they could certainly affect our knowledge of the quantitative level of the effect of greenhouse gasses. If, as you say in #75, that “… the cause of the current observed warming when the KNOWN physics of greenhouse gasses explain it perfectly well?”, then it would indicate that the amount which now works perfectly well must be an overstatement.”

    And, as Gavin and others have pointed out, again repeatedly, greenhouse gas forcings are fairly tightly constrained by the known physics, so it will not likely be greenhouse gas forcings that will have to be reduced to offset any net cloud forcing, but rather other less constrained forcings.

  8. Lynn Vincentnathan:

    Not sure if this was moderated out, or failed to be submitted, but here goes again (hint…I’m just joking below, but one way to look at what we’re doing to earth is a “natural experiment”)…

    RE #81, I guess, Jim, that you didn’t hear about the great multi-multi-trillion dollar experiment being conducted on global warming, and whether or not GHGs are the cause.

    It’s called appropriately “EXPERIMENT EARTH.” They were hoping to have a control planet, one exactly like earth, like Planet Gork from Galaxy Zork, but just didn’t have the funds. So they did the O X1 X2 X3… type of experiment: initial observation before treatment, then do the treatment (emit GHGs) in increasing increments, observing the effects along the way.

    It’s been very interesting to the scientists, and even a few of the public who’ve been able to tear themselves away from tabloid TV. By 1995 they began to get results, with the first studies reaching the .05 significance level that GHGs were indeed increasing the warming of earth. And since then the experiment-based evidence just continues to strengthen as GHGs are increased.

    Of course, there were some naysayers even earlier than 1995 saying we shouldn’t do such an experiment because it’s too risky, but the scientists said it would be just too expensive to go over to Planet Bork in Galaxy Zork to do it there. This earth of ours was the only place we could feasibly do such an experient, though it’s been very expensive indeed, even here. I mean, you have to get people to drive their cars thousands of miles on frivolous trips to nowhere, keep their lights on even when they leave the room, overdecorate at Xmas, jetset around the world, consume all sorts of products they don’t really need or even want, esp those shipped in from overseas (a few patriotic people have questioned this policy), refuse to buy energy/resource efficient products, refuse to buy the cheaper wind-generated electricity (well, I sort of caved to this one, but don’t tell anyone). And people for the most part have really have cooperated in all this. But it would have been really too expensive to ship all the people and their cars, etc from Earth to Gork.

    Now we have a bunch of naysayers saying we should terminate Experiment Earth, because we have plenty of evidence — you know, the way they say we should terminate medical experiments early because they’ve either been found to be exceptionally helpful…or quite harmful.

    But for the most part people are very cooperative and want to continue the experiment. I guess they think it’s kinda fun being involved in a scientific experiment, though it has been found that there are some side effects from emitting GHGs. Pollutants harmful to health also get released, causing for instance 60,000 deaths here in the U.S. alone each year from the small particulate matter (that’s like a Viet Nam each year), not to mention dying lakes and corroded forests, property, and lungs from acid rain.

    So the amazing thing is the people could be saving lots of money and improving their health and living standards by ending this experiment — by opting for energy/resource efficient/conservative products and meausres, and alternative energy — but they’re pretty good sports about wasting their money and health, all in the name of this great scientific experiment.

  9. Barton Paul Levenson:

    Jim Cripwell writes:

    [[I claim there is no EXPERIMENTAL data. There is no hard, measured independently replicated experimental data that shows a connetion between the increased level of CO2 in the atmosphere and the global temperature warming in recent times; i.e. since 1979.]]

    Just because you happen to BELIEVE that when a grocery item goes through the line, the checker puts it in a plastic bag, does not prove that the checker put the item into the bag. There is no hard, independently measured EVIDENCE that the checker put the item in the bag. Until you produce some, I will continue to believe that presently unknown solar influences caused the item bagging.

  10. RomanM:

    #100 Ray Ladbury
    What “pet theory” are you referring to? Is it the radical idea that decreasing cloud cover might be able to have a role in increasing temperatures by allowing more direct insolation on the surface? I can’t take any credit for making that one up. I presume you don’t think that to be a possibility to be investigated. Your science may be settled, but mine is not. As well, pejorative personal labeling of people who don’t subscribe to all of one’s beliefs is not conducive to an honest discussion of intellectual ideas.
    #106 Jim Eager
    If you recall, my original point was that it is not usually simple to show that something is NOT true since that can only be done if ALL reasonable alternatives are eliminated. The example of the clouds modulating the effect of the sun was simply one possibility that seems to be rarely mentioned and whose effects are not fully understood. Although it appears to me that a natural consequence would be an increase in surface temperature, I did not advocate any specific viewpoint.
    I AM genuinely curious about the effect of clouds. The first time I encountered the data on the decrease in cloud cover was after I was looking at the record April temperatures in Britain this year. A press release from Met Office
    went into great detail on how it was the warmest on record and included the statement
    “Recent temperature rises are in line with recent findings by Dr Peter Stott of the Met Office Hadley Centre and Professor David Karoly of the University of Oklahoma. Their research showed the recent rapid warming of the CET is almost certainly due to human influence – the first time this has been rigorously identified on such a small geographic scale.”
    However, the web page
    describing the weather at the time also shows that that month was the SECOND SUNNIEST ON RECORD with total sunshine that was 143% of the 1961-1990 average. Curiously enough, this did not deserve ANY mention in the press release.
    Yes, there are many factors which affect our climate and their relationship is complex. Leaving any of them out when modeling runs the risk of invalidating results, particularly when trying to quantify those factors. Because of the profession of my day job, at the present state of climate science, I would rather trust results from properly collected and analyzed data than from deterministic models based on “first principles” which do not necessarily take second principles (feedbacks and other factors) properly into account. Greenhouse gas forcings may be “fairly tightly constrained by the known physics”, but to produce a substantial effect, they also require feedbacks which may be altered or subsumed by other factors. However, that is a different issue.

  11. Chuck Booth:

    Re # 10 Romanm: “…there are many factors which affect our climate and their relationship is complex. Leaving any of them out when modeling runs the risk of invalidating results, particularly when trying to quantify those factors.”

    Why do you assume that climatologists haven’t considered cloud cover?

  12. RomanM:

    #109 Chuck Booth

    I don’t assume that. However, if someone could provide me with some references to what they would consider as good recent papers of the analysis of real data (not model results)of cloud cover in relation to temperatures, I would genuinely appreciate that. Relying on Google and sifting through what it finds is time consuming and hit-or-miss at best.

  13. Jim Eager:

    Re RomanM @ 110: “Relying on Google and sifting through what it finds is time consuming and hit-or-miss at best.”

    Try Google Scholor:

  14. RomanM:

    Thanks for the suggestion. I was hoping for something more specific, but at least this is may be better than straight Google.

  15. Ray Ladbury:

    RomanM, You evidently did not read my post very closely. My point was that climate modeling is not just a matter of selecting the forcings you like and allowing their magnitudes to vary until you match the data (the Chinese menu approach: one from column A…). Yes decreased cloud cover could play a role in climate. However, it could also lead to increased cooling, since clouds block both incoming light and outgoing IR. Second, the magnitudes of the various forcings are constrained to the degree possible by independent data–not fit to the trends being modeled. GHG forcing is quite well constrained. Other forcers–clouds, aerosols, etc.–are not. Now if you were to find that one of your ill-constrained forcings was important, would you expect it to affect your estimate of a well constrained forcing or another forcint that is ill constrained? There are a lot of things we don’t know about climate. The fact that anthropogenic CO2 is responsible for the current warming epoch does not fall into that category.

  16. Claudius Denk:

    Ray Ladbury Says:
    8 December 2007 at 10:03 AM
    Jim Cripwell,
    You claim we have no evidence that the current warming epoch is greenhouse driven.

    Uh, huh. This is a fact.

    Well, let us review: We have the very deep absorption line at the CO2 absorption band,


    which interestingly enough actually radiates about at the temperature you’d expect for a greenhouse mechanism.

    This statement is rather obvious nonsense. Support your argument. Show us supporting data (fat chance).

    We have the fact that a greenhouse mechanism can explain the qualitative aspects of the current warming–shorter Winters, warmer nights…

    Nonexistent evidence. There has been no change in night lengths, etc.

    We have the fact that we know it is operative.

    Obvious BS.

    We have the fact that it can be explained in terms of known and understood physics.

    If you believe this then you should do it. Go ahead. Show us.

    We have multiple, independent lines of evidence that fix CO2 forcing at its current level.

    BS. CO2 Forcing is immeasurable, undefinable!

    Shall I continue? What exactly are you looking for in the way of evidence?

    You don’t know?

    If you don’t know what specific piece of evidence would convince you, how can you consider yourself a skeptic and not a denailist?

    Are you not a cultists?

    In contrast, you posit some unknown forcing that may or may not be operative, that depends on unknown physics and that even if present and significant probably would not affect our estimates of greenhouse gas forcing, since this would require radical explanations of the multiple lines of evidence that fix that quantity. GCMs are not a Chinese menu. It is not a menu where you pick one from column A… Rather, anthropogenic ghg forcings are your vegetables. You can’t leave them on your plate and expect to get dessert.

  17. Hank Roberts:

    Wait, you need a sanity check here. You quote Ray as writing:

    >> shorter Winters, warmer nights…

    And you reply:

    > There has been no change in night lengths

    This does not compute. You won’t get a change in the length of the night without changing the rotation of the planet. This is not the same as warming it up.

  18. Barton Paul Levenson:

    Claudius Denk writes:

    [[CO2 Forcing is immeasurable, undefinable!]]

    It’s measured in watts per square meter, and is related to the amount of CO2 present relative to a reference level by

    RF = 5.35 ln (C / Co)

    where Co is usually taken to be the 280 ppmv preindustrial level.

  19. Jim Eager:

    Re Claudius Denk @113: “Uh, huh. This is a fact.”

    This from the same person who wrote: “Support your argument. Show us supporting data (fat chance)” and “If you believe this then you should do it. Go ahead. Show us.”

    And Claudius Denk: “Nonexistent evidence. There has been no change in night lengths, etc.”

    This from the same person who wrote: “Relevance?” and “This statement is rather obvious nonsense.” and “Obvious BS.”

    Enough said.

  20. Jim Cripwell:

    Ref 115 Claudius Denk is wrong when he said radiative forcing, as a measure of greenhouse effectiveness, cannot be defined. He is right when he said it cannot be measured. The formula you quote comes from Myhre et al, Geo. Res. Let. Vol 25, No. 14 July 15 1998 Table 3, and has quite clearly been calculated.

  21. Ray Ladbury:

    Actually, Jim, you can measure it. If you look at the IR emission spectrum from Earth, it ought to look like a blackbody at the effective radiating temperature of Earth’s surface. However, there are big holes in the wavelengths corresponding to ghg absorption lines. In fact, in these bands, it looks like emission is occurring at a much lower temperature, and that is in fact what is occurring. Guess what, Jim! Physics works!
    BTW, still waiting on you to tell us what evidence you would need to see to convince you. Even Thomas the apostle said he’d believe if he touched the wounds on Jesus’ hands–he was a skeptic; you are in denial.

  22. Jim Cripwell:

    Ref 118. Fine. Can you give me the refernce where the radiative forcing of CO2, as a way of specifying it’s greenhouse effectiveness, has been measured.

  23. Hank Roberts:


  24. Jim Cripwell:

    Ref 120. That is NOT a reference to a scientific study that MEASURED the radiative forcing of CO2. In fact, no such reference exists, or can exist. The definition of radiative foring is the INSTANTANEOUS increase of CO2, with ALL other factors being UNCHANGED. This is IMPOSSIBLE to do in practice. You cannot inject billions of tons of CO2 into the atmosphere instantaneously; and if you wait until the concentration increases “naturally”, other factors will have changed.

  25. Ray Ladbury:

    Jim, the argument you are voicing could be levied against all of stat mech and thermo–in fact any field where quantities are defined in terms of partial derivatives. Absurd positions like that are indefensible. Actually, the accompanying chart tells you pretty much all you need to know:

    Earth radiates as a black body atit’s radiating temperature. Yet the temperature in the CO2 band is much lower–indicating that a lot of energy is not managing to escape. What must that energy do? It has to heat the climate. Conservation of energy, Jim. Oh, but wait, you probaly don’t believe in temperature, since that’s defined as a partial derivative.

  26. Jim Cripwell:

    Ref 122. This is Real Climate, and I am a denialist. In a “scientific” discussion, I am never to going to have the last word. I have never read any previous case in the whole history of science, where the “science is settled”, and there is no experimental data to support that position.

  27. CobblyWorlds:

    #108 Ronan M,
    Two small points with regards our sunny April in the UK.

    Weather is not climate. Just look at April 2007’s CET figure abd it’s notably warm. Stott/Karoly are not claiming every warm month is due to anthropogenic forcing, but the overall trend is.

    This week it’s been below 10degC here in Lancashire, last week it was above 10degC. Yet last week it was cloudy and wet (wet implies heat “lost” from the surface as it’s converted to latent heat by evaporation), and this week it’s been sunny but dry.

    The answer is that direct insolation doesn’t have the effect you’re ascribing to it. Here in the UK our climate is dominated by the activity of air masses. In winter we get low pressures and they bring warmer maritime air with them, we get high pressure and it gives us continental/northern cold air.

    The Stott/Karoly study used a GCM, when they find an anthropogenic linkage they’re also considering wider regional climate systems like the Arctic Oscillation/North Atlantic Oscillation.

    For what it’s worth: As far as I’m concerned it’s settled.
    1) Strato and above cooling.
    2) Diurnal range behaviour.
    3) Continued warming.
    No trend in GCR – which would explain any cloud-albedo cause for the warming (without an external cause any trend in clouds could itself be due to AGW so you’d be confusing phenomenae and epiphenomenae).
    No trend in total solar irradiance.
    At the same time we have a rise in CO2 which theory predicts will cause observations 1, 2, & 3.

    Perhaps it’s because my degree’s in electronics, so I’m more of an engineer than a scientist as such. But from my point of view: If it walks like a duck, it swims like a duck and it quacks like a duck. Then it’s a duck.

    #113 Claudius Denk,
    Thanks for giving me a laugh.

  28. Ray Ladbury:

    Jim, so, you don’t believe the science is settled with regard to that whole pesky inverse square distance dependence for gravity? How about the round Earth hypothesis? The thing is that there are some things we KNOW. Evolution? And we know them by virtue of multiple independent lines of evidence. CO2 forcing is such a case. Proving we’re significantly wrong about it would mean explaining away mountains of evidence. Better get cracking, huh?

  29. Barton Paul Levenson:

    [[I have never read any previous case in the whole history of science, where the “science is settled”, and there is no experimental data to support that position.]]

    No matter how many times you repeat “there is no experimental data,” you will still be wrong. We have experimental data and we have observational data, and they both say CO2 is a greenhouse gas, there’s more of it in the atmosphere, and the surface is warming. We have measured the back-radiation from the atmosphere — hell, you can measure it yourself, if you can buy or rent the equipment. We have measured the radiation coming from the Earth by means of satellite instruments. The science is settled.

    What experimental data do you require? What finding would make you admit you were wrong? If you say, “there isn’t any,” then you’re just a troll wasting everybody’s time, and Gavin et al. ought to stop printing your posts.

  30. Lab Lemming:

    Welcome to the real world, Dr. Stoat. Incidentally, does your new job involve actually doing something about AGW, instead of just studying it? That was one of the attractions that drew me to industry…
    -Dr. Lemming