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

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

July 13th, 2012

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.

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  1. July 13th, 2012 at 15:32 | #1

    I haven’t “corrected” my claims because I still can’t see how I was wrong. Roger Jones would have been talking about a 5% real reduction, which is the same as your 25% reduction from BAU… so you are looking at the same thing and coming up with different numbers.

  2. Ernestine Gross
    July 13th, 2012 at 16:03 | #2

    “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.”

    For a few years I tried to get a handle on socio-political categories – I failed. But I feel comfortable with ‘social democracy’ as practised on JQ’s blog.

  3. Nathan
    July 13th, 2012 at 16:33 | #3

    @John Humphreys
    So, in this post JQ explained (again) the difference in assumed reduction starting points, and that he had ascertained what Roger Jones “would be talking about” by the radical technique of actually asking him. Have you also communicated with Jones about this? If not, may I ask by what reasoning you come to the conclusion that you are better informed about the gentlemen’s analysis than our host?

  4. John Quiggin
    July 13th, 2012 at 16:41 | #4

    @John Humphreys
    I’m going to repeat myself in bold 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.

    Obviously, in checking with Roger, my main concern was precisely what was meant by a 5 per cent reduction. I confirmed that Roger’s estimate was for a 5 per cent reduction relative to BAU, not the 25 per cent I was looking at (derived as a 5 per cent reduciton on 2000 levels by 2020, relative to the BAU estimate of a 20 per cent increase). Your assumptions about what he “would have been” talking about are false, as I’ve confimed in the most direct way possible, by going to the source.

    Just to hammer the point home, I’ve repeatedly invited you to do a simple reality check using tonnes of emissions avoided and a sensitivity number. I urge you, again, to do so.

  5. John Quiggin
    July 13th, 2012 at 16:46 | #5


  6. may
    July 13th, 2012 at 18:12 | #6

    i’m going off topic.

    what’s going on in NSW?

    what is the state labor party doing?
    what do they think they are doing?
    who are these people?who do they represent?
    not the likes of me, that’s for sure.

    the current federal government is the most representative government i can remember.
    the idea that the people who voted for representatives other than the two main parties are somehow of no account and mistaken in their choice of MPs is a contemptible slur on the choices of those who voted.
    as the federal Labor team manages to govern as a true coalition by negotiation with elected representatives not of the Labor Party in the face of an incompetent,obstructive opposition why is NSW state labor trying to derail this?
    who are they?
    who are they working for?
    sqabbling for internicine advantage.
    secret reports to where was that again?
    coupled up apparatchics working against political rivals on the national stage,providing opportunity for federal opposition to sidestep their role in parliamentary debate by wasting question time in a frenzy dribbling nastiness.
    we see a shambling shadow that has gone past dysfunctional.
    there is no function to dys.
    unable to even pay it’s own way.
    maybe the best thing is to just pull the plug.
    call in it’s debts,dissolve the central branch and start again.
    disbarring any in the old branch.
    it would be no loss,any body who was doing the work for the principles worked out under the tree would have left ages ago.
    maybe they could put together a NSW Labor party that actually spoke for the people that do the work.
    instead of playing into the hands of those who think the richest need looking after.
    delete if you like JQ

  7. Jim Rose
    July 13th, 2012 at 19:06 | #7

    Not interested in your trolling, Jim – JQ

  8. Sam
    July 13th, 2012 at 20:00 | #8

    So, to summarize, the two scenarios involve a factor of ~ 5 difference in temperature reduction, but also a factor of ~ 5 difference in CO_2 reduction, leading to rough agreement on temperature sensitivity. Both men use BAU, which is the appropriate reference for measuring the effect of policy. Good, so that’s settled then.

  9. July 13th, 2012 at 20:36 | #9

    I’m very skeptical. The article you link to is clearly talking about a 5% real reduction (not against BAU) which is Australia’s policy. It would be very strange for Jones to study a 5% reduction against BAU since that is not on any agenda for anybody.

    I would very much like to see Jones directly enter the debate to clear things up.

  10. John Quiggin
    July 13th, 2012 at 21:18 | #10

    I repeat – do the calculation directly, using tonnes of emissions avoided and the sensitivity number cited by Bolt. In fact, you don’t need to – I’ve done the calculation here


    Unless you can find something wrong there, I suggest its now incumbent on you to retract.

  11. July 13th, 2012 at 23:32 | #11

    What on earth is “real” reduction if not against “Business as usual (BAU)”?

    Please explain the definition of each term, as you use it, to explain the difference. I can’t see what you mean otherwise.

  12. Sam
    July 14th, 2012 at 01:00 | #12

    A “real reduction” means a reduction from current levels. So if we at the moment Australia emits 500 million tonnes, a real reduction of 5% by 2020 means that in that year we emit 475 (500-0.05*500) million tonnes.

    A reduction from Business As Usual means a reduction below what would have happened without the policy. So if, under business as usual estimates, Australia is likely to emit (say) 600 million tonnes in 2020, a reduction of 5% from BAU means that in that year we emit 570 (600-0.05*600) million tonnes. Note that in this case a “reduction from BAU” means a real INCREASE.

    Is it dishonest or tricky to use BAU? No, not if you’re clear about what you mean. We certainly want to get a real reduction (and not just a BAU one), but when we’re estimating the effect of a policy, we need to consider what the world would look like in its absence.

  13. Sam
    July 14th, 2012 at 01:01 | #13

    “So if we at the moment “=>”So if at the moment “

  14. Hermit
    July 14th, 2012 at 08:22 | #14

    Combet et al tell us we are aiming for 159 Mt emissions reduction relative to BAU. However 5% of year 2000 emissions of 553 Mt is a less impressive sounding 28 Mt. The big number fails the truthiness test.

    Other untruthy aspects of our concern for global carbon are plans to double coal exports and treble LNG exports. Should perchance carbon capture and storage not work by 2015 we are supposed to buy foreign offsets, a mid-range cost estimate being $25 bn. I suspect that if the ALP can hang on til 2015 instead we’ll slip the Indos a few dollars to save some forest with its cute orangutans. No doubt they’ll do a good job just like they are doing stopping the boats.

  15. BilB
    July 14th, 2012 at 09:09 | #15

    This is a nonsense discussion.

    The aim is to eliminate 90% of our CO2 emissions. The 5% is simply the highest figure that every effort could get politicians to commit to in public.

    You’ve all completely lost the plot here. Let’s get back on message.

    Do you really need to have your own house demolished and your livelihood washed away by extreme weather before you focus on the true reality of the situation.

    The denialists have done a wonderful job of getting everyone’s expectations watered down to very little, and now even aguing about that last little bit, even though extreme weather is delivering an ever increasing toll of destruction. What’s in stall for us this summer? We’ve had the flooding rains, its time for some bush fires, with the consequent house fires, again. And doesn’t News Ltd just love all of this.

  16. BilB
    July 14th, 2012 at 11:33 | #16

    Has the threat to our environment dissipated,….or gone away? Absolutely not.


    Totally the opposite. The feedback mechanisms thought to accelerate Global Warming are now kicking in, and this is evidenced very clearly in the Arctic. And everywhere else in a variety of ways. Just last week 1500mm, yes a metre and a half, fell over eight hours in one area.

    Apart from the ever increasing intensity and frequency of extreme weather events, the undeniable evidence that the atmosphere is changing is in the changing pattern of high and low pressure systems visible every night on the evening weather reports. At this time of year, winter, the high pressure systems should be tracking across central Australia in an orderly fashion. Not any more. They now like to reside below Australia summer and winter. Atmospheric air movements have altered very dramatically, far faster than atmospheric science can study and report on quantitatively. The end result of these changes still results in “weather”, it is just very different,…and we don’t know where it is leading to, other than an end game of apocalyptic heat for most of Australia.

    We ignore these changes at our peril. You pay attention to the denialists and Tony Abbott at peril to your intelligence.

  17. Ikonoclast
    July 14th, 2012 at 13:01 | #17


    “Do you really need to have your own house demolished and your livelihood washed away by extreme weather before you focus on the true reality of the situation.” – BilB.

    Yes, they do BilB. On a global scale, a lot of that is going to have to happen before people take this threat seriously. A string of salutary disasters will happen to humanity before we collectively take any effective action. The disasters will get so bad that they will prune the population for us since we wouldn’t limit and stablise birth to death rates and growth ourselves.

    Arguing about 5% improvement when you really need 95% improvement to give even a 50% chance of saving the situation is beyond even black comedy. The ” endless growth capitalism until total collapse” brigade have won. Well, I hope they enjoy their “prize”.

    I think all people (including me I admit) are now living either in total ignorance or effective total denial. The horror, tragedy and inevitable nature of all this are too big to contemplate. I’m getting a 5.5 kw array of solars plus solar hot water on my roof. It’s all tokenistic and useless now. My family comprises four adults at home (with kids over 18) and has 3 cars, a ride-on mower, chainsaw, push mower, weed eater, 2 TVs, 4 computers etc etc. That’s got to be totally unsustainable. I’m as bad as the deniers.

    No human really wants to live like a “sustain-abilist”, a survivalist or a hunter-gatherer and no human will adopt such life modes voluntarily. It’s an extraordinarily tough life. All over 50s will die in short order (for example). Infant mortality will go back to something like 1 in 2. Etc. etc. The picture is so bleak that to paint it just promotes more denial.

  18. Annabelle
    July 14th, 2012 at 19:37 | #18

    Bolt, Quiggin…whatever. All estimates are well below what could possibly be detected. These heated arguments about the undetectable remind me of nerds who argue about the details of the Star Trek universe.

  19. iain
    July 14th, 2012 at 20:03 | #19

    No point having this argument. Bolt wins regardless. He just creates the narrative that the carbon tax won’t have much effect, and even the experts can’t, apparently, seem to agree on the (very small) amount of benefit. To the average punter it is very compelling, particularly if he can keep an exchange going for a long time. The best way is to ignore him.

  20. BilB
    July 14th, 2012 at 21:29 | #20


    There are a lot of arguments one could make of the intesimal.

    Why should we have a seat at the United Nations, we are just one of 200, what possible influence could we have?

    Why should I pay my $20,000 tax, it is such a small percentage… 0.000007%, as to be almost imeasurable? Try not paying it and see how upset Tony Abbbott gets about that.

    Conversely the governemnt should only tax people with lots of money because only they can make a difference. Try on that argument and see how hysterical Tony Abbott gets, and how quickly he forms a coalition with the Libertarians.

    Yes lets delve into pointless endlessly obfuscating arguments that ignore the reality that in large systems….every little bit counts.

  21. Hermit
    July 14th, 2012 at 21:30 | #21

    Though the pundits tell us Abbott is a shoo in for the next election there may soon be a repeat of the factor that helped elect Rudd … the presence of El Nino weather patterns with climate concerns by the public. Ironically it is a form of direct action that has helped the US achieve significant emissions cuts without explicit carbon pricing. That was an EPA emissions benchmark for power stations that coincided with their shale gas boom. However if as some predict cheap natural gas in the US will only last another decade then coal could make a comeback. Like Australia the US has joined the coal export bandwagon which gels with views that Chinese coal output has peaked.

    I think this time next year our emissions cuts will be modest compared to the large amounts (100s not 10s of Mt) advocated by climate scientists. Renewables will increase a smidgin and the economy will be subdued. If next summer is a scorcher voters will have ambivalent feelings about Abbott; they’ll want both decisive climate action and a return to strong economic growth. Perhaps they’ll end up with neither.

  22. BilB
    July 14th, 2012 at 21:34 | #22


  23. July 14th, 2012 at 22:50 | #23


    Last year China imported more thermal coal from Mongolia than it did from Australia.

    We really need to re-think our self-important hubris because of this idea that our rocks are better than everybody else’s!


  24. July 15th, 2012 at 02:00 | #24


    sorry to come into this late and I have written a longer explanation that I hope will be soon posted at The Conversation. I calculated a 5% reduction from 2000 by 2020 and came up with a reduction in temperature in 2100 of 0.0038 degrees for a 3 degree climate sensitivity. I used the simple climate model MAGICC for this.
    A second calculation estimated a further 80% reduction by 2050. This produced a reduction of 0.02 degrees by 2100. Both estimates are proportional to Australia’s burden of global emissions. Let’s say that we wanted to reduce from the BAU estimate of 5.3 degrees in 2100 to 2 degrees for example and likened this to a 42 km marathon. Australia’s 2020 target is equivalent to 48 metres and the 2050 target is about 250 metres. Australia would get the direct benefit from the 250 metres we ran and the other 41 km 750 m that all the other nations ran, if successful.
    The Andrew Bolts of this world want to deny the simple truth of these sorts of numbers.

  25. July 15th, 2012 at 02:12 | #25

    Oh, and to address John Humphrey’s comment at #9, the benefit is not very sensitive to the underlying emissions – it tends to be net. This is not strictly true but the differences are less sensitive than differences in climate sensitivity and emission rates. Where it does matter is for overshoot rates where emissions get to less than the natural take-up – about 55% fewer emissions than the world is putting out now. If the world is appreciably warmer, this number will need to be greater because the natural sinks will be less efficient than they are now.

  26. BilB
    July 15th, 2012 at 10:04 | #26

    A good article on the dangers of over (and under) extrapolation (projection).


  27. BilB
    July 15th, 2012 at 12:32 | #27

    I am going to post this (my) comment from Roger Jones excellent site as i believe that it is rlevent to this thread also. The comment is to a Mike who claims that Bolt has “won again” and that Jones should give up and shut up.

    “Mike @ 11.29

    Bolt only “wins” arguments through censorship/selective publication. If you do not understand that then you are a toadie and not worth talking to.

    The real fact(s) that Bolt a). does not understand, I would venture, and b) will never talk about is the true cost of the .0038 C.

    Australia’s global temperature .0038 policy impact share must be assessed as its part of the GLOBAL ECONOMY.

    It is a global temperature which is relative to the global economy. Do you understand the distinction?

    The Global Economy which will be reduced to near zero by a 5 degree C rise in temperatures is what is at stake here.

    In todays terms this is $69 trillion. Australia’s current .0038 policy impact share on that economic activity is $236 billion. In fact it is the inverse of that. ie if all Austalia achieves is a .0038 degC improvement then its share of saving the the global economy amounts to just $236 billion in today’s terms.

    However, if Australia achieves a .02 degree C reduction in temperature rise then its improvement share to the global economy will amount to $1.35 trillion. In other words we will have saved the Australian economy at a short term marginal cost.

    Do you understand this?

    Andrew Bolt is a technologic Dunce. If you swallow his swill then you will become a Double Dunce. More significantly, your children will have no future and almost certainly die young.

    I have just been outside after being inside all morning. It is summer here in Emu Plains NSW, in the middle of winter. That is both weather and changed climate.”

  28. Happy Heyoka
    July 15th, 2012 at 13:36 | #28

    Bolt is a paid entertainer, it’s his job to be controversial. I suspect he may even enjoy it.
    I’m certain he’s intelligent enough, given time and study, to understand the strength of the evidence but having nailed his colours to the mast, he may have a problem backing down.

    Even so, I admire John Quiggin, Tim Lambert and others who take the time to try and engage him.

    The facts speak for themselves, more clearly with every year that passes, and those who choose to ignore them will pay the price in due course.

    Unfortunately, for those of us at or approaching middle age, that time is far enough away that we will probably all be being spoon fed in a nursing home or feeding the worms.

    The white hats, having been vindicated, do not get to ride triumphantly off into the sunset…

  29. BilB
    July 15th, 2012 at 14:03 | #29

    Happy Heyoka,

    At middle age your later years may well be spent in the full onset of climate change. In fact your life will almost cerainly be cut short if climate change and resource depletion proceed unrestrained.

    Your most certain climate change related fates include

    heat exhaustion/stroke, drowning, crushing, hyper thermia, failure of services/medicical resources, incineration (while alive), lightning strike, loneliness induced suicide, starvation.

    On current Coalition Climate Mitigation policies one of those fates will be yours if your body does not fail due to desease or medical condition.

    There is no room for age complacency here. Remember it is not just Climate Change Risk to be concerned about, resource depletion is guaranteed to limit our ability to do the changes that are required to limit our CO2 emissions. The steady upward march of the price of oil will within the next 8 years cause even stable economies to fail.

    That is absolutely guraranteed.

  30. Freelander
    July 15th, 2012 at 14:21 | #30

    The idea that only the unborn will suffer significant consequences from climate change is fanciful. Change is accelerating,and the most consistent aspect of forecasts is that they have underestimated changes, and that with every new report they have been revised upward.
    Unless you have scheduled your departure for this year or next, worry!

  31. Hermit
    July 15th, 2012 at 15:12 | #31

    To solve the problem of whether it is ‘our’ coal just carbon tax finished goods from China and India on the presumption that they are coal intensive. For administrative simplicity make the carbon tariff 10% or 20%. If they say the embodied energy was clean let them hire lawyers to make the case.

    Australia, the EU, Nordic countries and others could form a low carbon customs union to enforce this. When China and India have CO2 penalties remotely resembling $23/t we can drop the tariff. As a bonus we may not have to subsidise our metals industries so much, for example 94.5% carbon tax exemption and $300m cash for steel.

  32. Happy Heyoka
    July 15th, 2012 at 15:38 | #32

    @Freelander, @BillB while I don’t in general disagree, you miss my point(s)

    I’ve spent a good deal of my professional life doing things like optimising temperature control in a furnace that takes months to heat or cool and, conversely, tracking and processing events that take nanoseconds or microseconds.
    Human perception just doesn’t cope with extremely time spans (eg: heating or cooling something with the thermal mass of an ocean).

    Second, I’ve spent a lot of time dealing with complex interactions between complex systems.
    Human perception also doesn’t cope well with that kind of thing. Climate is complex – I’ve messed around with trying to correlate and process some of the data sets for personal interest. I highly recommend it if you wish to feel humbled.

    While I totally agree that BAU will result in a catastrophe of proportions unseen by modern human society, it’s not going to happen like a car crash all in one instant, and attribution of the adverse biosphere events will remain peskily difficult – always leaving room for “it was the sun” or “it’s a natural cycle”.

    I don’t disagree with the need to get working on mitigation efforts, personally and professionally I’m doing all I can with what I have.

    My interest outside of that, in the “political sphere”, is in trying to understand how otherwise intelligent people (eg: Bolt) either don’t get it or decide to manipulate those who “don’t get it”.

    Exploiting the limited attention of people who’s main concern is next months mortgage payment is neither a new or a novel technique but it’s effective… a persuasive argument by someone like Bolt has these folks thinking “well, that’s all right then” and off to the sports pages.

    Mitigation Efforts suffer a lot of turbulence and drag from this.

  33. BilB
    July 15th, 2012 at 16:35 | #33

    Good on you, HH.

    The comment is not directed at you personally, but at the attitude that we, the control generation, will personally escape the consequences of our actions,…so why should we care.

    The comment is also directed at those who imagine that they can delay action until the effects such as sea level rise are about to engulf their home at which point a simple change of mind will put the situation back to “normal” and the problem will just go away after some tidying up and the planting of some new shrubs.

    Tell me, though HH, do you appreciate the rapidly approaching risk to economic stability due to resource depletion? And further the consequent risk to climate change adaptation?

  34. July 15th, 2012 at 16:37 | #34

    @Happy Heyoka

    “My interest outside of that, in the “political sphere”, is in trying to understand how otherwise intelligent people (eg: Bolt) either don’t get it or decide to manipulate those who “don’t get it”.

    Exploiting the limited attention of people who’s main concern is next months mortgage payment is neither a new or a novel technique but it’s effective… a persuasive argument by someone like Bolt has these folks thinking “well, that’s all right then” and off to the sports pages. …”

    No, you actually explain it perfectly.

    That’s why I’m so pedantically ANTI Murdoch at every turn (won’t tollerate a single click on News Ltd or anything that further enables the very phenomenon you identify there).

  35. Freelander
    July 15th, 2012 at 17:38 | #35

    I’m always amused by the conceit of the weekend scientists and their adventures in modeless data manipulation, where the professionals seem to require just that bit more equipment and training.

    Turning to Bolt as a source of peer review … say no more …

  36. Freelander
    July 15th, 2012 at 17:45 | #36

    Bolt probably has no doubt that anthropogenic climate change is real, but will nevertheless continue his posturing while laughing all the way to the bank.

  37. July 15th, 2012 at 19:33 | #37

    From the comments above from Roger Jones it is now clear that my interpretation was correct and JQ was wrong. Jones has clearly said “I calculated a 5% reduction from 2000″, which is a real reduction, not a reduction from BAU.

    JQ earlier: “I’m always happy to check for, and if necessary correct, errors in my calculations.”

    We will see…

    Given the repeated public claims that I was refusing to correct “erroneous claims”, a small apology wouldn’t go astray either. The peanut gallery who mindlessly clapped along to the JQ tune might also let this be an opportunity to pause and re-think.

  38. John Quiggin
    July 15th, 2012 at 20:46 | #38

    @Roger: Sorry to press you on this, but as you can see the issue remains live. I understood you as saying that you compared a 5 per cent reduction by 2020 to an alternative of no change. Can you spell out the trajectories you had in mind?

  39. Happy Heyoka
    July 15th, 2012 at 23:09 | #39

    @John Quiggin, John Humphreys

    Have any of you (AB, RJ, JH, JQ) published something like a spreadsheet? You know, starting assumptions for emissions, temperature rise per tonne, that sort of thing? I’m guessing all of you used one and didn’t just scribble it out long hand.

    I followed some of your links and the Herald Sun stuff in particular is now pay-walled (the actual print copy here is probably well and truly used by the puppy by now).

    It might be informative to approach it that way rather than bat “who-did-what-how” backwards and forwards…

    I have no idea how well accepted Damon Matthews methodology is… given it’s been a couple or three years since the Nature article in question there should be some discussion of that by now.

  40. BilB
    July 15th, 2012 at 23:22 | #40

    Excellent suggestion,HH.

  41. Happy Heyoka
    July 15th, 2012 at 23:50 | #41

    The relevant Nature article is pay-walled… this seems to be a relevant discussion:


    (apologies in advance if the link embedding fails…)

    It’s worth reading the comments to see just how complicated it is to try and give a simple answer…

  42. July 15th, 2012 at 23:57 | #42

    John Q,

    sorry – thought I’d been quite clear when we spoke but may not have distinguished the Australian baseline from the global baseline sufficiently. I did say that I’d taken the -5% from 2000 to 2020, then run it through to 2100. You then said (I think) that was equivalent to your assumption from the level of treasury growth – I agreed. The temperature run that I then did was that reduction from a global BAU – namely the Garnaut A1FI (that I originally ran for the Garnaut Review – I set up the scenarios they used). So it’s Australia acting to 2020 as per the policy of the Laboral, sorry, Libor parties, then maintaining that when the rest of the world does not.

    The -5% in 2020, then -80% in 2050 was the 0.02 degree in 2100 reduction. However, that was reduced from a different scenario – this one is A1B on steroids, which reduces global emissions from about 2040.

    A bit more work needs to be done to make all of this publishable – running them under a wider set of global assumptions, basically.

    Have just check the spread sheets to confirm. Will not be releasing them until I have the results submitted and reviewed. Not sure when that will be. I could publish some summary graphs but there is a lot going on and would have to do a bit of work on presentation.

  43. BilB
    July 16th, 2012 at 07:59 | #43

    And in the latest bizarre weather news, while Southern Japan is getting the Toowoomba treatment, there is an outbreak of three tornadoes in Poland, the second such series in recent times (the first being in 2008).

    Of course it is just a fluctuation.

    And, yes, I watch the foreign news casts on SBS as the ABC thinks that reporting Tony Abbott declaring that he will “get rid of that toxic tax” for the six thousandth time is actually news.

  44. Happy Heyoka
    July 17th, 2012 at 22:29 | #44

    ok, so I’m a dummy: the more comments I read regarding the link I posted, the more I realised they were talking about a different Nature letter by H. Damon Matthews (guy is a rockstar, has been published in Nature proper as well as Nature Geo.)

    The correct article is The proportionality of global warming to cumulative carbon emissions

    I hope nobody misspent their hard earned because the spiders in my wallet prevented me from stumping up…

  45. Mark
    July 22nd, 2012 at 00:24 | #45

    So you were wrong. And yet you claim to be an expert etc etc ad nauseum add the usual crap and call me a denier and now are getting a taxpayer funded sinecure to perpetuate this shameless mess of lies and exaggerations for base political purposes.

    I guess the cash makes it all ok. Your conscience must be a wonderfully malleable thing.

    You and your ilk disgust me. History will laugh at you. That is my consolation, your legacy will be trashed along with many others of the sycophants and zealots on the gravy train.

    Enjoy it while you can. You have just over 12 months before the piper will be paid.

  46. BilB
    July 22nd, 2012 at 01:04 | #46

    Mark,…your’re upset! Didn’t get your milk and cookies and couldn’t sleep?

    The best thing is to think positive thoughts, and you will drop off to sleep in no time at all!

  47. Baa Humbug
    July 22nd, 2012 at 01:23 | #47

    @Roger Jones

    If the world is appreciably warmer, this number will need to be greater because the natural sinks will be less efficient than they are now.

    Natural sinks? Global vegetation would be one of those sinks, and the last I looked, very little vegetation grows at the cold polar ends of the world. They seem to like warm and wet a la the tropics.

    Leaving the sarc aside, we need to admit that our knowledge of the carbon cycle and the forcings and feedbacks that influence our climate is lacking (as the IPCC so acknowledges in the Summary for Policy Makers, levels of scientific understanding).

    In which case, making far reaching important economic decisions based on low levels of understanding which may or may not reduce global temperatures by a poofteenth of a degree seem to me to be bad policy.

  48. TerjeP
    July 22nd, 2012 at 01:24 | #48

    John Quiggins update in which he withdraws his assertion that Andrew Bolt and John Humphreys got it wrong (on that point) gets a response from Andrew Bolt:-


  49. Freelander
    July 22nd, 2012 at 02:04 | #49

    The deniers seem to get sillier and sillier as the evidence for AGW gets stronger and stronger. One can feel their pain. That pain shared with the terrible twos toddler throwing a temper tantrum.

    It is funny though.

  50. BilB
    July 22nd, 2012 at 03:08 | #50

    And what far reaching economic decision would that be BaaHumbug?

  51. Freelander
    July 22nd, 2012 at 03:19 | #51

    Don’t worry about Baa Humbug, no surprise deniers pulled the wool over his eyes.

  52. Tony
    July 22nd, 2012 at 05:42 | #52

    Oh dear, some very serious egg on face here for both the author and a large number of bloggers who piled in to criticise Andrew Bolt in particular. To all those who are so ready to attack the intelligence and motives of anyone who disagrees with their ‘climate’ beliefs I suggest it is time to consider the way in which you approach the debate.

    Fact is Bolt is right. He was right all along and there is much the ‘warmists’ need to learn from those like Bolt who actually analyse and understand the underlying issues rather than mindlessly repeating the strident trumpet calls of the fear mongers.

    Sadly I expect that even public humiliation like this is not enough to bring about a change in attitude though. Fear does that to people – makes them impervious to sense and sensibility. You only have to read some of the comments here about 5 degree rises in temperature and fanciful extreme weather events to realise which side of the debate is being driven by mindless fear.

  53. Graham
    July 22nd, 2012 at 07:55 | #53

    “I appear to have misinterpeted (sic)…”

    Not only a prize goose, but a grammatical dumb ass as well.

  54. Mark
    July 22nd, 2012 at 08:37 | #54


    Marvellous retort BilB. Full of consensus science and the matter to hand.

    Quiggan was wrong. Painfully wrong. So wrong in fact he should hang his head in shame but of course that does not get one a publicly funded job these days does it?

    Perhaps you should look at what is occurring and not what is modelled or lied about to further the appropriation of public funds.

    It isn’t hard son. you will pick up the whole concept of thinking for yourself in no time.

  55. July 22nd, 2012 at 09:17 | #55

    Whether it’s 0.0038 or 0.02 degrees, where are you going to find a thermometer to measure such a small temperature difference? They don’t exist. Thermometers do not go beyond one decimal place.
    So you want to enact a government policy that will make such a small temperature difference that it can’t even be measured?

  56. Baa Humbug
    July 22nd, 2012 at 09:18 | #56


    Don’t worry about Baa Humbug, no surprise deniers pulled the wool over his eyes.

    And that was the sum of your contribution. Well done.

  57. BilB
    July 22nd, 2012 at 09:21 | #57

    No Freelander,

    BaaHumbug represents the entire Coalition and all of those people who do not have the time or inclination to follow the science of Climate Change so accept their information predigested, acidified and regurgitated from the likes of Bolt. He must be addressed, particularly now.

    BaaHumbug, I will assume, is suggesting that the tiny Carbon Pricing regime that Australia has enterred into is a “far reaching economic decision”, and he holds that view I imagine because Andrew Bolt has told him to think that. The likes of Bolt and Abbott who who can only deal with one “fact” at a time are unable to comprehend that the Carbon Price is the first and only mechanism put in place to protect the Australian economy not only from Climate Change, but Peak Oil as well.

    BaaHumbug is so enraged by the red herring being dangled in his face by Bolt that he does not see that he is being gouged on his electricity pricing by the power companies who are quietly escalating the cost of energy beyond any precedent in Australia’s history. The Carbon Price red herring at 2 cents per unit ……the power companies 10 cents per unit. And if BaaHumbug and his like kind idiots are stupid enough to vote in Abbott, the 2 cents per unit will not come off, there will be another 6 cents added. If expect that it will take BaaHumbug ten years to do the maths on that little con. And the most tragic aspect to this is that the power generators will then be earning heaps more cash to carry on as usual exacerbating the CO2 problem immensely.

    And that is very much part of the reason why Quiggin has no need to retract. The calculation is incomplete. The BAU scenario is far worse than predicted in so many ways. CO2 emissions in the hands of the religious right will increase 50%, and the Earth has many more surprises in store for CO2 emissions of its own inresponse to the escallation. This is what Roger Jones was referring to.

    And if all of that was not bad enough, there is Peak Oil. Petrol prices are vascillating by 30 cents a litre at present. This gives some indication of the instability of the oil supply, as well as the greed of the oil industry. This means a cost variation of $450 dollars a year for me even for the tiny amount of driving that I do. This is the tip of the energy dilemma heading our way. Economies are already being destabilised by their energy costs at the Peak while oil demand is still being met. In just a few years time when oil delivery dips below the global demand economies will start to fail significantly.

    Electrification of industry and transport is the only viable solution for a table economic future for most countries in the world. But standing in the way of that is the genius of …..Tony Abbott. The mouth. And the other idiot….Andrew Bolt. The Pen.

    But let’s not forget BaaHumbug. The thinker.

  58. Baa Humbug
    July 22nd, 2012 at 09:26 | #58


    And what far reaching economic decision would that be BaaHumbug?

    CO2 is a byproduct of modern activity. taxing and or trading CO2 as a commodity has far reaching effects. Artificially increasing the cost of energy has far reaching effects.
    It hasn’t been a difficult political outcome for no reason.

  59. Baa Humbug
    July 22nd, 2012 at 09:28 | #59

    Grow up

  60. Hermit
    July 22nd, 2012 at 09:39 | #60

    I have mixed views about Prime Minister Abbott’s direct action plan since by accident or design it could generate bigger emissions cuts than carbon tax. The fact the US has made significant cuts without an explicit carbon price has been put down to recession, shale gas (fracking) and EPA smoke rules.

    I expect around election time when CT has disappointed we’ll hear all the horror stories of new coal plants being built. We won’t hear how CT could be made tougher so I’m ambivalent about a change of government. BTW the US has joined the coal export bandwagon so nobody is perfect.

  61. BilB
    July 22nd, 2012 at 12:04 | #61


    You clearly do not have the ability to even read your electricity bill properly. Give it a go, get out your electricty bills going back a few years, or use your neighbour’s bills (I imagine you chuck yours in the bin). It is all there, real evidence of what is going on right under that ring through you nose.


    You should really start to prepare your thinking for the most probable outcome of this coming election, another minority Labour government. See, you did not think of theat possibility did you. Abbott has so poisoned the waters of cooperation that if there is a hung parliament it will be a very short negotiation period with a predetermined conclusion.

    I’m expecting this contest to be an all smoke without mirrors election. Nothing focusses the mind on Climate Change like having your house burnt down. Here we are heading towards August and in Penrith it is Summer. Take a look at the graph


    check out the nose dive into el nino. That coupled with how Climate Change is intensifying the climate systems says pretty clearly that there will be devastation where a fire gets underway this summer.

    Prime Minister Gillard, re-elected will have a lot work to do putting Australia back together.

    So, Hermit, what do you think of my new campaign to have gun owners pay into a compulsory third party personal insurance programme to pay the costs of the victims of guns, as we do for cars?

  62. TerjeP
    July 22nd, 2012 at 12:14 | #62

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

    1. Flip flops by the ALP
    2. Lies and deceit by the ALP
    3. The decision to spend a large slab of the revenue on Green Schemes rather than return it via reductions in other taxes.

    John Howard implemented MRET with barely a whiff of objection. And yet it is far more destructive than a simple revenue neutral carbon tax. To be sure there has been an active campaign against the carbon tax by ALP opponents but if the ALP didn’t have the three problems I listed above then I doubt that campaign would have the traction it now does.

    The most simple way to introduce a basic carbon tax without all the fuss would have been to repurpose fuel tax as an environmental initative instead of as a road funding device. It could then have been lowered and broadened to include fuels used to make electricity (like coal and gas) and fuels used in mining and agriculture. It wouldn’t have been perfect but it would have been politically much simpler.

  63. BilB
    July 22nd, 2012 at 12:15 | #63

    Dr Chemical,

    Everyone has a thermometer that measures 5 degrees C (extra), and that is what they will need in just a handfull of decades from now if we lose the fight on CO2 emissions. But what whoever is left at that point really will need, is a wall to hang their thermometer (likely to one of a handful of prized possesions) on. That will be much harder to achieve. Probably a cave at that point will be the safest.

  64. BilB
    July 22nd, 2012 at 12:38 | #64

    Off topic.

    A quick look at for the US, gun related deaths equal car related deaths. For Australia car deaths are about half that for the US, but surprisingly gun deaths equal two thirds of that number. Now considering that gun ownership is relatively rare in Austalia, to that high a total means that the handful of gunowners are really clumsy.

    So gun owners can all soon anticipate paying $200 per year per gun in third party personal compulsory insurance. And victims of gun crime and their families can finally look forward to proper compensation for their suffering.

  65. TerjeP
    July 22nd, 2012 at 14:00 | #65

    BilB – on what basis do you claim that firearms are rare in Australia?

  66. BilB
    July 22nd, 2012 at 14:06 | #66

    I said relatively rare, Terje, meaning I personally know no-one who owns one, whereas I do personally know several Americans who own them. Relatively. I am willing to bet that a study of the official numbers would bear that out.

    Do you own a firearm, Terje?

  67. Hermit
    July 22nd, 2012 at 14:11 | #67

    El Nino could save Gillard the same way it helped Rudd back in 2007. If the public finds both major parties wanting on climate change perhaps they could go Green, though I suspect the Greens have lost both charisma and common sense absent Bob Brown.

    Suppose by next election we have lost a pissweak 5-10 Mt of emissions which is not on track for what climate scientists think should be at least 100 Mt in absolute terms between 2000 and 2020. Who can keep supporting the Gillard polluter-gets-paid plan? Abbott might allow nukes which some current senior govt MPs (eg Albanese, Conroy, Cameron) plus Greens will block. Then again Abbott sees no problem with coal.

    Since my neighbours like to go spotlighting at 1 a.m. I’ve gotten used to gunfire. The US should not only have a gun buyback but also find an alternative term to ‘gas’ for liquid motor fuel. I suspect that the crazies who do the massacres seldom get guns through orthodox channels therefore any insurance claims could be voided.

  68. TerjeP
    July 22nd, 2012 at 14:33 | #68

    BilB – from memory the Australian Institute of Criminology study done a while ago showed that one in ten Australian households had one or more guns.

    I don’t own a firearm. However I have been shooting in the last twelve months and so has my 11 year old son. I think that our gun phobia is a strange social phenomena.

  69. BilB
    July 22nd, 2012 at 14:39 | #69

    The illegals will always be so. The insurance is for the 90% of firearms and the consequences. There are those who drive cars illegally, too. What the policy will mean is that all victims of gunshot incidents will get treated and Australian and US health insurance costs will go down a little bit (for the US a lot).

    The cost of the insurance will reduce gun ownership with out infringing on those all important “rights”. The gun lobby in the “user pays” US economy will not have any reasonable recourse.

    BaaHumbug (perhaps to his credit) must be off looking up his electricity bill. Lets hope that he takes up his findings with Bolt, not that he would get published for his efforts.

  70. BilB
    July 22nd, 2012 at 14:47 | #70

    As I said, Terje, the firearms death toll from that small gun holding is surprisingly high at two thirds of the road death toll.

    I don’t think that Australia has a gun phobia, it is that we have more gun sense. There is a difference.

  71. TerjeP
    July 22nd, 2012 at 16:51 | #71

    As I said, Terje, the firearms death toll from that small gun holding is surprisingly high at two thirds of the road death toll.

    Annual firearm deaths for Australia is about 250 on average although it jumps about year to year. Road toll annually is about 1300. So your figure of two thirds is way too high. The correct figure will be closer to one fifth.

    90% of households have no guns. 10% of households have no cars. You can still make the argument that guns are therefore more lethal than cars but the effect is not as large as you have implied.

  72. bananab
    July 22nd, 2012 at 17:28 | #72

    So after all the to-and-fro Prof. Jones has confirmed a temperature reduction of 0.0038 which is what Mr. Bolt said right at the start, perhaps an apology would be in order. Other scientists have calculated smaller decreases, eg. Prof. Mathews 0.00024 and Dr. D. Evans 0.0007. The climate commissioner (Prof. Flannery) is either incapable of calculation an estimate or more likely too ashamed to admit how small the figure is. I suspect that applies to Steffen, Combet and Gillard also.
    But the real people can all agree it is a piddling and insignificant temperature decrease for an enormous cost. But moreso is the fact that the small reduction in Australias emissions will be dwarfed by the increase in emissions from other counhtries such as China, India, Brazil and other countries

  73. BilB
    July 22nd, 2012 at 17:30 | #73

    Well it was a quick survey, I bow to your more studious appraisal. An insurance policy approach will look carefully at the real figures and costs and arrive at a third party personal figure. The figures on injuries are interesting. Obviously the percentage of gunshot injuries is very different to the figure for car accident injuries (non fatal) and it would be interesting to see the serious injury comparison.

    The notion of an insurance policy approach is really a reaction to the crazy situation in the US where the gun lobby have the politicians stitched up on gun control. The best you can hope for in that environment is to find a monetary deterent. And the best approach towards that end is to require the gunslingers to pay for the damage that they cause.

    The same logic, though, fits for Australia, where a significant share of the beneficiaries of the scheme will be the gun owners themselves, the ones who shoot themselves in the foot, that is.

  74. BilB
    July 22nd, 2012 at 17:56 | #74


    Roger Jones calculation, though, scientifically based is certainly conservative. I had a look at this from another direction, and that was to see what the economic impact of no action would be. The curious thing is that it seems that the economy falls over at a very shallow temperature rise. From that perspective the perceived small impact of Australia’s CO2 emissions reductions is amplified.

    Conversely, your claim of “an enormous cost” is blown out of all proportion and completely disregards the many positive contributions that the Carbon Price makes to the Australian economy. Once the intense negativity of the religious right fanatic Tony Abbott has been removed from the economy after the next election when his defeat leads to his being dumped from the Coalition and he withdraws from politics altogether, Australian industry will surge forward on a wave of renewables energy infrastructure investment.

    I suggest that you take a look at what is happening right now to the US farming belt. A severe drought has set in and is demolishing there productive capacity with average temepratures 5 degrees higher than normal. This has come on very rapidly. It was only several years ago that many of these areas were experiencing 1 in 1000 year rainfalls just months apart.

    You, no doubt, think that you are defending against some great wrong, but you are infact serving to create certain economic catastrophy beyond your wildest imagination. you might care to read all that Roger Jones has published on Climate Change, not just the one sentence that serves your momentary argument.

  75. Baa Humbug
    July 22nd, 2012 at 19:02 | #75

    Like I said, grow up if you wish to have a civil discussion.

  76. Baa Humbug
    July 22nd, 2012 at 19:06 | #76


    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?

  77. Freelander
    July 22nd, 2012 at 19:23 | #77

    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!

  78. TerjeP
    July 22nd, 2012 at 19:27 | #78

    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.

  79. TerjeP
    July 22nd, 2012 at 19:34 | #79

    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.

  80. Fran Barlow
    July 22nd, 2012 at 19:44 | #80


    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.

  81. Fran Barlow
    July 22nd, 2012 at 19:52 | #81


    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.

  82. Baa Humbug
    July 22nd, 2012 at 20:00 | #82


    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.

  83. Freelander
    July 22nd, 2012 at 21:17 | #83

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

  84. Freelander
    July 22nd, 2012 at 21:26 | #84

    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.

  85. BilB
    July 22nd, 2012 at 21:37 | #85

    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.

  86. Troy Prideaux
    July 23rd, 2012 at 14:55 | #86

    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.

  87. Freelander
    July 23rd, 2012 at 16:42 | #87

    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.

  88. Troy Prideaux
    July 23rd, 2012 at 16:58 | #88

    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.

  89. Freelander
    July 23rd, 2012 at 19:53 | #89

    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?).

  90. BilB
    July 24th, 2012 at 05:50 | #90

    A scientist on politics on science……


    a very good read

  91. TerjeP
    July 24th, 2012 at 10:53 | #91

    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.

    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.

  92. Freelander
    July 24th, 2012 at 15:11 | #92

    Terje, font of scientific knowledge and wisdom. I think not.

  93. Fran Barlow
    July 24th, 2012 at 17:03 | #93


    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.

  94. Nick
    July 24th, 2012 at 20:22 | #94

    “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.

  95. Fran Barlow
    July 24th, 2012 at 20:49 | #95


    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.

  96. Nick
    July 25th, 2012 at 09:32 | #96

    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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