Every now and then, in my reading online, I come across a summary of some kind which I wished I had had the gumption to compose myself. This short couple of paragraphs, by ‘Bryan’, appeared in the Comments on a Judith Curry piece by Robert I. Ellison, an Australian engineer who comments a lot there (and to useful effect, in my view). Here it is.

Considering the uncertainty, the way forward seems clear. Continue to study (climate money should go toward collecting data and studying it, not solar and wind subsidies), but in the meantime, promote policies that increase prosperity and decrease poverty. And avoid policies that do the opposite. When and if we determine that CO2 is harmful, we will be in better shape to address it if we are rich than if we are poor.

Making the world poorer in an attempt to lower CO2 emissions doesn’t make any sense to me. First of all, we really don’t know that the CO2 is hurting anything. Second, even if it is, we don’t know whether our attempts will slow down CO2 emissions enough to help (proposed and enacted policies to date have had little influence on CO2 levels). Explain again why we should continue and expand policies that put a damper on the creation of wealth and make it harder for people to get out of poverty?

Much of the discussion and one of the key elements of Ellison’s own essay, was about the sheer uncertainty of all the stuff about global warming. How much is it warming? (Compared to when?) To what extent are human beings responsible for the warming? (We’re not really sure.) Is warming necessary bad? (Well, not at the moment, but it might be later.) How much later? (Well, we’re not really sure.) Is it true that sea-level rise is accelerating? (Well, it depends on what data set you are looking at.) What about ice melt? (Well, that’s really complicated…) And so on. Judith Curry herself moved from being a supporter of the orthodoxy to a sceptical position because in her view the uncertainties were simply too great to carry the confidence of the IPCC reports, and the policies that these reports have generated.

‘Bryan’ makes three points. The first is the need to keep studying climate, especially through collecting excellent data. I wrote a piece on the funding of science, and I won’t go far down that path here. But it seems to me that something that the Abbott Government could easily do would be to alert the CSIRO and BoM to the need to devote resources to generating the best baseline data now and in the future, rather than in telling us yet again that Australia is getting warmer and that bad things might follow. And its advice to SES agencies everywhere might be that they and their bosses should prepare for the next floods, droughts and fires without worrying too much about whether or not they are the result of higher levels in carbon dioxide in the atmosphere.

The second point is that we simply don’t know now whether or not carbon dioxide increases will eventually be harmful to us. Since the relationship between carbon dioxide increases and temperature is logarithmic it will take a good deal of time to tell. To double the carbon dioxide proportion in the atmosphere from the estimated 280 ppm prior to the Industrial Revolution to 560 ppm (we are at about 400 ppm at the moment) will take quite a time at current rates of warming, which are virtually static, if not cooling. It will eventually produce 1 degree Celsius of warming, unless climate sensitivity is quite high (and 1 degree C looks about right, at least at the moment). The next doubling, to produce another 1 degree Celsius, would be from 580 ppm to 1160 ppm. That does seem a really long way off. So we have time to learn: as ‘Bryan’ says, ‘When and if we determine that CO2 is harmful…’

The third of his points is not just that ‘action’ now could be most premature (the subject of yet another forthcoming post), but that we are likely to be a good deal wealthier as the 21st century progresses, and will know a great deal more, especially if we have better data (point one). If there are adverse consequences, we will be in a much better position to address them, because we will have a lot more money, all things being equal.

The orthodox objection here is that we must reduce carbon dioxide emissions, and the sooner we do so the easier it will be to have an effect. The trouble is that nothing we can do can have an obvious effect. It’s not just Professor Flannery’s admission that whatever Australia did about emissions wouldn’t be seen for a thousand years. I wrote last year about the handy calculator you can use, developed from work by the American National Center for Atmospheric Research, to see what would happen if you constrained carbon dioxide emissions in some form and accepted the IPCC’s 3.0 multiplier for climate sensitivity, and sought to see what would happen by 2050 or 2100.

I played with the calculator, and could see that if the USA got rid of all carbon dioxide emissions then by 2050 there would be a reduction of 0.052 degrees C in the global temperature. In fact, it doesn’t matter how you play with it, the result is that to get any appreciable reduction in temperature the human world has to to give up electricity, gas, motor vehicles and planes. It isn’t going to happen. And on the face of the current data, that is not a problem.


Join the discussion 6 Comments

  • David says:


    Your understanding of statistical inference is puddle-deep.

    Firstly science behind AGW is not a simple univariate model. As
    any casual observer will tell you, orthodox or sceptic, the relationships are
    complex. So to conclude “since the relationship between carbon dioxide
    increases and temperature is logarithmic it will take a good deal of time to
    tell, is breathtakingly simplistic.

    And the reason that any moderately attentive Year 9 science student can tell that other processes must be important, is by simple inspection of the data. Here is a log function


    And here is a graph of global temperature rise


    They obviously look nothing alike. One function is convex and the other concave!

    Secondly, if you were going to make a prediction of temperature using a simplistic univariate model, at the very least you would need to say something about how fast you expected CO2 to increase to make a meaningful prediction. For example, when Arrhenius first identified a causal relationship between CO2, even though he used a sensitivity factor of 1.6, he predicted it would take 3000 years to obtain a
    1.6 temp rise. The reason he was out by so much was he could not appreciate how quickly CO2 would increase next 100 years.

  • DJA says:

    “And here is a graph of global temperature rise


    No it is Not, It is a graph of the CHANGE in temperature rise, and therefore of little relevance to your argument. Perhaps try again. But I must admit some of Don’s statements are also a bit wobbly – like “Since the relationship between carbon dioxide increases and temperature is logarithmic”

    • David says:

      I don’t agree but humor me whats your point.? 🙂

      Mine is that Don keeps on trying to dazzle with a reference to “logarithmic” relationship between CO2 and temperature to infer that any temperature rise must therefore be slow and inconsequential.

      This is a log function

      y = log x^n

      Just looking at that you cant say one way or the other how “quickly” y will change in response to a change in x.

      This is my point.

      • DaveW says:

        Looks to me like plots of annual and 5-year average estimated surface temperature deviations (anomalies) from the 1951-1980 mean through most of 2007. So, it doesn’t claim to portray global temperature per se. You would get different patterns if you used different reference periods. Perhaps that is DJA’s point.

        Apparently there are statistical arguments for using anomalies over actual temperatures, but it does make interpretation more difficult. Certainly there appears to be no simple relationship between these anomalies and annual mean atmospheric CO2 concentration. One wonders why the data stops in 2007, given that it is now 2014?

      • DaveW says:

        “Since the relationship between carbon dioxide increases and temperature is logarithmic it will take a good deal of time to tell.”
        This struck me as a bit off when I read it too, but I assume Don is referring to the fact that CO2’s ability to limit the loss of radiant energy to space is not a linear function of atmospheric concentration and that most of its effect on global temperature had already occurred before levels started rising. A 1.2 C increase in global temperature for a doubling of CO2 is a value that is commonly bandied about and the effects of adding blankets sometimes used as a metaphor: the first couple do all the heat retention then there is little to no increased effect. I think most climate scientists accept that and rely on hypothesized feedbacks through water vapour etc. to get more warming.

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