Quiggin and Bolt: One last try for agreement on the numbers

I was at the Australian Conference of Economists earlier in the week, and had a chat with Roger Jones, who has occasionally commented here. I asked him about his estimates of the impact of emissions mitigation policies in Australia, and was able to confirm that our estimates, although reached in very different ways, are in quite close agreement. Roger is cited here and here, estimating that a 5 per cent reduction in Australia’s emissions would result in a reduction in equilibrium global temperature of 0.0034 degrees. In a blog comment, I made the estimate that a 25 per cent reduction, relative to business as usual (the official target of the carbon price policy and also of the Opposition’s ‘direct action’ alternative) would result in a reduction in equilibrium global temperature of 0.02 degrees.

Unfortunately, Andrew Bolt did not observe the reason for the difference, and suggested that we disagreed by a factor of five. For the second time, a comment I sent correcting the mistake was lost in moderation. I was inclined to give up at this point, but given that Bolt did admit an error in his own estimate that I had pointed out to John Humphreys[1], I thought it would be worth one last try.

Policy disagreements are inevitable, but it would be helpful if we could avoid unnecessary disputes over arithmetic. I’m always happy to check for, and if necessary correct, errors in my calculations. If Bolt and others could do likewise, we would have a better chance of making progress in public debate, or at least of avoiding regress.

Update I appear to have misinterpeted my conversation with Roger, though I need to check on a number of issues before making a final assessment. So, I’m going to withdraw my claim that Bolt and John Humphreys in error on this point, and discuss the estimates with Roger in more detail. I’ll report back when this is complete.

Further update Unsurprisingly, Andrew Bolt has enjoyed a bit of a gloat on the subject, and some of his fans have joined in. So, it’s worth reminding everyone that he was out by a factor of 100 in his own calculations, presenting the impact of one year’s emissions reductions as if it was the total effect over the next 100 years.

96 thoughts on “Quiggin and Bolt: One last try for agreement on the numbers

  1. @TerjeP

    Baa Humbug – the reason the carbon tax has been a hard sell is in my view due to three factors:- etc etc

    You may well be right.
    I personally am not convinced that CO2 is the devil its made out to be. Colour me sceptical.
    And just like I exercised my right to vote against Howard for sending us to a useless war based on lies, I reserve my right to vote against any party that introduces a tax (however large or small) based on flimsy evidence and one which will never achieve what it’s supposed to achieve.

    Ain’t democracy grand?

  2. Colour me skeptical, surely you mean just plain dumb? Deniers have to be assessed as stupider by the hour as the evidence accumulates adding to what has already been a long overwhelming scientific case for the reality of AGM and the role of greenhouse gases. Many are fools,but no other fool but the climate change denier is so valiant in demanding that the rest of the world acknowledge their foolishness!

  3. Baa Humbug – I work in the coal sector and I would hardly do so if I thought CO2 was evil in the way it is characterised by some. I also will vote against Labor (I’ll vote 1 for the LDP) in a big part due to their dishonesty. I was hopeful in 2007 that Labor would prove it’s critics wrong but in fact it has been vastly worse than I expected. Which is a pity because the Liberals are not such a thrill at times either.

  4. Freelander – the role of CO2 in Greenhouse warming is modest. To get any decent warming from an increase in CO2 you need to assume a number of strong positive feedbacks. The existance of these has never been proven but is merely inferred from the historical CO2 and temperature trends. There is still plenty of room for debate regarding temperature sensitivity with regards to CO2 and other emissions. Calling people dumb does not advance the debate.

  5. @TerjeP

    the reason the carbon tax {price} has been a hard sell is in my view due to three factors:-

    1. Flip flops by the ALP

    There have been one on this policy, with the arguable exception of the “citizens assembly”. That hardly rates a mention. Allowing it to be called a tax opened the door to trolling of course.

    2. Lies and deceit by the ALP

    There were none, on this policy.

    3. The decision to spend a large slab of the revenue on Green Schemes rather than return it via reductions in other taxes.

    It wasn’t a large slab, and I suspect that has been the most popular part. Abbott is proposing, in theory at least, to spend a large slab of revenue on “green” direct action schemes.

    Most of the money is being handed back in rebates. Some is being handed out as free permits — and although I regard this last as poor policy, it’s not that unpopular.

    People have been led to believe that this will change their lives radically for the worse and falsely invited to imagine that the government lied about it. “there will be no carbon tax”. When they discover that the scare is baseless and that reversing the CEF means handing back their threshold allowance, one supects they will notice that there was no lie nor even a breach of promise.

  6. @TerjeP

    I work in the coal sector and I would hardly do so if I thought CO2 was evil in the way it is characterised by some.

    Classic strawman … “evil”. This is what happens when you spend too much time in the Boltiverse.

    To get any decent warming from an increase in CO2 you need to assume a number of strong positive feedbacks. The existance of these has never been proven but is merely inferred from the historical CO2 and temperature trends.

    Yes … that’s how science works. One shows proof of principle. Then one examines data and makes inferences. One tests alternative hypotheses and rules them out as they fail to explain observed trends. Charney sensitivity has been very well specified for some decades now. Hansen’s 1981 forecast has been borne out.

    No literate person who has read the science could declare as you have, so you’re either dissembling or haven’t read the science or haven’t understood it. I regard “dumb” as an undesirable term on a number of grounds, but that still leaves us to characterise your stated views above.

  7. @TerjeP

    Thanks for the chat Terje.
    No point commenting any further on this blog. The locals seem quite angry that some people such as myself don’t agree with their views, shock horror.

    Professor Quiggan, nice company you keep here. good luck with your blog.

  8. Hard to be angry with fools Baa. Doubt that you can help it that you’re a fool. So no anger, only pity.

  9. Only a fool debates a fool, Baa. Ridiculing not debating is the way to deal with fools. The only person who can solve a fools foolishness is the fool. Step one the fool has to recognize that they are a fool. When the laughter at their stupidity is loud enough, one hopes they get the hint.

    One lives in hope.

  10. Terje, I can’t believe that you said that. Making a living with carbon is what we all must do for the time being, but deluding oneself of the implications is another thing altogether.

    Humbug, you didn’t actually make any comment here, so Baa Baa.

  11. Channel surfing over the weekend, I somehow landed on 10 to see the last 5mins of the Bolt Report. Surprise Surprise, he was blabbering on about this issue, but Gillard was the target this time.

  12. Bolt is laughing all the way to the bank. He’s probably unconcerned with the truthiness of his waffling. As long as supporters and foes keep his ratings up he can continue to turn controversy into cold hard cash.

  13. @Freelander
    Absolutely. What’s more, he’s just an ideological mouthpiece for the Murdochs, Rineharts etc pulling the strings at the respective media corps to fashion BS into fact for that particular willing herd.

  14. Rinehart has to have been cleverer than the Packer kid. He took his inherited fortune and gave it a quick hair cut by using his talent to choose a series of dismal investments; she simply held on to what she inherited and waited for the Chinese to make her the richest woman in the world. Be interesting to see how clever Murdoch’s brood will be after he leaves what he can’t take with him and moves to the upper house (or should that be lower house?).

  15. Yes … that’s how science works. One shows proof of principle. Then one examines data and makes inferences. One tests alternative hypotheses and rules them out as they fail to explain observed trends.

    Agreed.

    Charney sensitivity has been very well specified for some decades now.

    Charney postulated a sensitivity figure between 1.5 °C-to-4.5 °C for a doubling of CO2. There is a big difference between the top and the bottom of the range. To say it is well specified and has been for decades depends a lot on what you mean by well specified.

  16. @TerjeP

    Charney postulated a sensitivity figure between 1.5 °C-to-4.5 °C for a doubling of CO2.

    Actually Charney (1979) proposed 1.65 °C-to-5.2 °C … Calculation from direct physical evidence since that time have put the sensitivity towards the middle of that range. Thus Lorius (1990) {3.0 °C-to-4.0 °C} Hoffert (1992) {1.4 °C-to-4.2 °C} Hansen (1993) {2.0 °C-to-4.0 °C} Chylek (2007) {1.3 °C-to-2.3 °C} Tung (2007) {2.3 °C-to-4.1 °C} Bender (2010) {1.8 °C-to-4.1 °C} Schwartz (2010) {0.9 °C-to-3.9 °C}. The feedback assumptions account for most of the variability, but even at the minimum end, the consequences are quite dramatic. It’s not going to be trivial. Moreover, as the perturbation from CO2 is likely to last on most estimates for several tens of thousands of years, absent some drawdown technology or some you beaut geoengineering with unknown consequences, the temperature will remain significantly elevated with all that entails for at least some centuries after humanity stops being a net contributor to atmospheric concentrations of CO2. The consensus position assumes a minimum warming close to 2 °C for a doubling of atmospheric CO2 with a most likely value of 3 °C. 4.5 °C is not excluded. So we get to choose between very difficult, disastrous or catastrophic. bear in mind also that unless we act, doubling (560ppmv) is on the low side. Under b-a-u we are looking at 750ppmv by 2050. If we don’t act early we may get it anyway as the Arctic permafrost decomposes and starts a new round of positive feedbacks.

    Uncertainty, such as it is, is not humanity’s friend here.

  17. “There is a big difference between the top and the bottom of the range.”

    As I understand it, one would more or less completely wipe out life as a result of methane gas explosions 100,000 times more ferocious and destructive than the world’s entire stockpile of nuclear weapons, and enough hydrogen sulphide released from the oceans to fatally poison the world’s population 1000 times over.

    The other would simply displace 100s of millions of people as large swathes of the northern hemisphere turn to dust bowls, and our sea levels rise by 5 to 6 metres.

  18. @Nick

    Not sure about the comparisons at the catastrophic end but it’s very clear that the planet could become pretty much uninhabitable by the vast majority of humans over time and the rest would be living at a fraction of their comfort. If the clathrate gun hypothesis is borne out matters get even worse. There are scenarios in which these seas become emitters of toxic sulphides, wiping out most of life.

    Presumably, human societies would act before these scenarios became unavoidable. (I say presumably because I’m an optimist). The trouble is that the preventive measures would also have unknown consequences and might produce seriously negative unintended consequences. Certainly, biodiversity would crash on land and in the marine environment. The humans that survived would be living on a radically diminished world. Given that this is the only planet in the universe known by us to support life, this would be a tragic existential irony — being a species with the wit and the resources both to author catastrophe and to prevent it but impeded by its own usages from doing so until it was too late and the old positions were irrecoverable. I’m reminded of that astonishing but telling climax in that famous 1960s flick, Village of the Damned.

    I remain amazed that deniers and apologists for b-a-u can cite uncertainty as if it favoured their position, when there is no scenario in which the costs of action mact the likely costs of inaction. It’s a position of utter recklessness that ruthlessly mocks the concerns they typically express in relation to balanced budgets and inter-generational debt. Here they wink at catastrophe and smile broadly at disaster.

  19. Interesting, Fran. Thousands of pop culture references aside, I realised I hadn’t actually seen Village of the Damned, and watched it late last night on Youtube. (I realised then that I’d read the Wyndham book as a child.) The child spells his name with bricks early on…have to give that some thought. Great film.

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