Quick thoughts on climate sensitivity

This climate sensitivity thing. Lewis, Annan etc.

It reminds me of something and I just cannot remember where I first saw it.Can\’t even remember which number it was about.

But the general argument went that if a scientific number gets estimated (any number, distance of the Moon, Plank\’s Constant, whatever) and the original estimate is well off then you never really do find anyone leaping up and shouting \”Eureka! That\’s Wrong!\”.

Instead, over time you get a series of \”refinements\” from different authors the effect of which is to walk that estimate back to something much closer to reality. The implication was definitely that \”everyone\” knew that the original was well off. But no one really wanted to say so. Thus rather than confronting the error it gets slowly revised.

Does seem to me as if that\’s happening over sensitivity. Only an impression, but…..

As to what it means: it means that it\’s all a much cheaper problem to deal with. The more time we have the cheaper any solution will be.

Firstly, if we don\’t have to Act Now! then we can wait until the technologies actually mature before installing vast amounts of them. It really isn\’t going to be that long, wouldn\’t think more than a decade, before solar is truly price competitive (40% efficient multi-junction cells for example) at which point their installation won\’t even be a cost of combatting climate change. It\’ll just be a natural reaction to a relative price change. The same is true of other technologies (although I\’m not sure if windmills will ever make it).

Secondly, it means that we can (or at least could) work with the capital cycle rather than against it. Rather than replacing coal plants right now, as the EU is insisting we do, we could run them until they fall apart. Replacing them with renewables at the end of their life is obviously cheaper than closing them down early.

One way of describing this is that we move into a Nordhaus world rather than a Stern one. Instead of a medium carbon tax now, Stern\’s $80, we could have a low now (Nordhaus suggests $5) but with a committment to raise it strongly to say $250 in 2040, 2050. There\’s very little of our energy infrastructure that won\’t be replaced anyway before 2050, but this would allow us to get the most use out of what we\’ve already built and paid for.

Not that I expect a change in the science to actually feed through into a change in the political activity, more\’s the pity.

39 thoughts on “Quick thoughts on climate sensitivity”

  1. Pretty sure the original is related by Feynman, most likely in The Pleasure of Finding Things Out. My copy is at home and now this is going to bug me all day.

  2. Secondly, it means…

    You seem to be (judging from your broken Forbes post) to be assuming that the sensitivity is likely less than 2 oC. This is the same stupid misreading that the septics have made; its a shame you’re parroting their errors.

    Tim adds: No, I’m not assuming that it’s under 2. The logic works for “lower” sensitivity. If we all thought that it used to be 4 and now that it’s 3 then it still gives us more time and whatever it is that we have to do becomes cheaper.

  3. Yes, Feynman does talk (perhaps in his Cargo Cult speech) about exactly that: people are reluctant to trust experimental results against socially acceptable ones, if I can put it like that. This has been obvious in climate science for a long time.

  4. I think it’s far too early to say that estimates of climate sensitivity have changed to the extent that the necessary policy responses have also changed.

    Annan’s comments seem reasonable and he certainly has credibility on this topic but there are others such as Ray Pierrehumbert who disagree that the “fat tail” can be ruled out based on paleo evidence. And even if Annan is correct it only slightly reduces the worst case scenario, it doesn’t significantly change our “most likely” estimate, which has been around 3C for some time.

    I don’t pretend to have any expertise on this but I’m not convinced that we can ever find a “true” value for CS, or even significantly lower the current range of estimates. For a start I think it reasonable to expect that it would differ depending on starting conditions, and it also depends on what timescale you are looking at – some feedbacks may only manifest themselves over very long periods.

  5. Worth also pointing out that the lesson Feynman takes from it is different from Tim’s interpretation (if it’s the example he’s thinking of) – that it’s not that everyone knew it was wrong but didn’t want to say so, but that when they got wildly different values in their own experiments they looked for reasons why they might be wrong and discarded them when they found them, whereas when they were closed to Millikan result they figured they’d got it right and didn’t check so hard, thus skewing the numbers. Over time, each new value would then be ‘comfortably’ close to the one that had gone before.

  6. > Not that I expect a change in the science to actually feed through into a change in the political activity, more’s the pity.

    What has science to do with this? It’s a belief system, that remains impervious to reason. It’s the greatest hubris to believe that by controlling the emissions of one trace gas in the atmosphere mankind can predictably control the climate.

  7. I do like the comment on the Forbes post from “mememine” who seems to think that Occupywallstreet are sufficient of a generic authority that merely because they didn’t include anything about climate change in their list of demands that this is probative evidence against climate change 🙂

  8. C’m’n, Tim, plenty of us have been telling you for ages that the thing is a scam. The plausible bit is that it’s got milder since the troughs of the Little Ice Age, but the buggers have so polluted the data that we can’t even tell how much milder. The “You’re all going to roast in hell” stuff started, I suspect, as error (golly, they’re dim compared to the usual run of physical scientists) and ended up as lies to protect their positions.

  9. science is never that simple. These sensitivity numbers are the product of (many) deluded minds. Minds that have no meaningful concept of reality.

  10. Agree with dearieme. It’s always had the flavour of L Ron Hubbard about it. I’m still waiting for the CAGW community to market a device, measures the temperature of its own batteries, we can carry around to prove to ourselves its happening.

  11. BIS.
    Climate scientists/activists (for they are largely interchangeable) have always struck me more like the population of the ‘The Wicker Man’ island.

    Keep sacrificing the people, guys.

  12. All remotely plausible estimates of climate sensitivity (including Lewis’s) are still within the IPCC’s original (1990) range of 1.5 to 4.5. The report was reluctant to specify a single value, but remarked that “a value of 2.5°C is considered to be the best guess in the light of current knowledge.” (p139).

    Whereas James Annan now says, commenting on his earlier estimate of 3°C, “2.5 might have been a better choice even then”.

    So no, the estimate of the most likely value has not been significantly revised. All that’s happened is that as the science has matured, the top end of the range of sensitivities has looked less likely to apply. But it wasn’t thought to be probable in the first place.

  13. “the top end of the range of sensitivities has looked less likely to apply. But it wasn’t thought to be probable in the first place.”

    It’s commonly forgotten that the outer ends of almost any confidence interval are considered far less likely than the ones in the middle. I seem to recall most people’s mental model has the probabilities distributed uniformly between the limits, and so leads to them overestimating the probability towards the tails, but I can’t recall the particular research that demonstrated this.

  14. PaulB>

    One might wonder why the range was 1.5-4.5 if the ‘best guess’ was 2.5. A cynic would suggest that there’s plenty of evidence that it was semi-deliberately done to exploit the effect MBE mentions.

  15. Stuck Record I think it was called Sark …. no actually summersisle …. but Sark is a reasonably substitute

  16. Please note: the Nordhaus carbon tax is based on the frog-in-a-pot idea. Put the frog in hot water and he jumps out. Put him in slightly warm water and then turn on the gas under the pot – the water warms so slowly that he never jumps out, and boils in the end. Frog-in-a-pot was the basis for Kyoto. There, the idea was to get governments locked into binding agreements. Once bound, then gradually tighten the screws, with the citizens unable to do anything about it. Thus we all become frogs-in-the-pot.

  17. PaulB>

    A scientist would laugh at the suggestion that a change in temperature can only be positive, which is what you’re suggesting there. It’s clearly nonsense if you stop to think for half a second about what it would mean if the temperature sensitivity was ‘bounded below by zero’.

  18. @ Dave
    We are not discussing whether *any* change can be positive or negative but whether *the change caused by burning billions of tons of fossil fuels* can be positive or negative. As I have repeatedly said, as a sceptic about the claims of both extremes in the debate, the laws of thermodynamics mean *that* change can only be positive.

  19. @ Tim
    “you never really do find anyone leaping up and shouting “Eureka! That’s Wrong!”
    I beg to differ: quite often you do, but the general reaction is to tell the pesky blighter to shut up because he can’t know what he’s talking about – the expert knows best. It’s like when a schoolboy finds a mistake in a textbook: only the best teachers will listen. Harry Markopolos told the SEC half-a-dozen times that Madoff was a crook.

  20. John77>

    Thermodynamics: the Earth’s not a closed system. Your argument is invalid.

    The IPCC’s estimate of climate sensitivity cited by PaulB is including feedbacks. It’s perfectly possible for that to be negative. The plausibility of that is another question, but Paul’s fundamentally wrong to say it’s only possible for it to be positive.

  21. Er……if I remember my early seventies, climate scientists ( don’t laugh) had pollution from the Industrial Revolution* down as the cause of the Little Ice Age. They were warning, if we didn’t cut down on burning fossil fuels we’d have a full blown one ahead of schedule.
    *Yeah. Took a bit of date fudging but……all in a good cause. Doesn’t have to be true to be correct.

  22. Or is that “doesn’t have to be correct to be true”

    DOCTOR William S Connoley (with the ‘e’) would know the proper climate science terminology.

  23. @ Dave
    I do know that the earth is not a closed system. That does NOT invalidate my point.
    The rate at which heat leaks into space is proportional to the temperature difference so burning fuel *must* increase the temperature of the earth compared to what it would have been if that fuel had not been burned.
    You are just failing to think.
    As to “feedback” that could suddenly cause a fall in temperature as a result of a rise in temperature, you need to postulate an unstable system that can be pushed into a cataclysmic event by a change – well, that won’t wash because the highs and lows of the global temperature cycle are well above and below current levels.

  24. I’m curious as to whether anyone is charting the gradual drop over time of the ‘consensus’ figure for estimated climate sensitivity to CO2. Presumably we should be able to extrapolate from this and predict when it will hit zero. My guess is around 2020. And of course, when this happens nobody will have been ‘wrong’ — they will have merely ‘overestimated’.

  25. John77>

    Er, yes, the Earth’s directly warmed a miniscule amount by the actual burning of fuels. But that’s not what we’re talking about here.

    “As to “feedback” that could suddenly cause a fall in temperature as a result of a rise in temperature, you need to postulate an unstable system that can be pushed into a cataclysmic event by a change”

    No you don’t. Why not postulate a simple warming correction with overshoot?

  26. Dave: so let’s postulate a mechanism by which increased carbon dioxide causes warming which causes after some time lag increased carbon take-up, to the extent that carbon dioxide actually decreases relative to its original level. Then you get cooling which after some time lag causes atmospheric carbon dioxide to rise, then…this is an oscillatory system, not one with a negative climate sensitivity.

    But we know this doesn’t happen, at least not in a time-scale measured in centuries. We’ve been burning fossil fuels for that long, and atmospheric carbon dioxide has increased monotonically.

    Jon J: you can chart the estimates from the five IPCC reports. You get a horizontal line.

  27. ” But it wasn’t thought to be probable in the first place.”

    So why was it quoted in the LITERATURE? And now, why nare all the “authorities” back-pedalling> and whay is 2.5 deg seen as scary when it used to be 5 or 6 deg?

    The question remains, how do you explain the rise in global temperatures in the 1930s. and then the subsequent decline till the mid 70s. We know that the increase in the 1980s and 90s has been ascribed to AGW. But then, what explains the standstill-= albeit with lots of “noise” – in the 200s? And don’t drag out a purely land-based temperature series such as BEST to claim that we are all doomed.

  28. Regarding feedbacks, there are negative as well as positive feedbacks, the main one being the lapse rate feedback, but these are more than compensated for by positive feedbacks such as water vapour and albedo. A net negative feedback effect is extremely unlikely as it would be incompatible with what we know about past climate change, such as the changes between glacials and interglacials.

  29. Diogenes: there’s a whole range of values in the literature, arrived at by various researchers using various methods. That’s the way science works. If you want a consensus, you review what’s been published and quote a range of values covering the best-quality work. That’s what the IPCC has done.

    If you take a steady drift, and superimpose on it various oscillations each with its own period and phase, you’ll get a noisy chart which seems to have a varying trend, including periods of rapid increase and periods of apparent (noisy) standstill. There’s no mystery. Here‘s a paper which attempts to filter out the ‘noise’ effects.

  30. The global warming debate is no longer about the science, it’s about the politics, or Houyhnhms versus Yahoos.

    Watch Richard Muller at http://www.youtube.com/watch?v=xxCSkckihDk to see how the IPCC reports have been hijacked and distorted by alarmists. In the same video, Dr. Muller politely rebuts a questioner who feels that science should say what politics tells it to.

    Although Dr. Muller’s stance is anti-CO2 he’s neither an alarmist nor a groupthinker.

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