Tim Worstall

George Monbiot on Ice Melts

Quite wonderful is George today. He picks up on Hansen’s recent paper about the possibilities of albedo flip (the ice sheets aren’t going to melt over hundreds and thousands of years, but this century) and thus we’re all doomed.

He entirely misses one very important point in the paper. Page 13 in that link (1937 as the journal counts it). We are following the A1B emissions scenario from the SRES: as we’re also pretty obviously following the A1B economic scenario. That makes all of the Stern Review, based as it is upon the A2 family of scenarios, somwhat moot.

Something that, in turn, means you can’t really go around using both studies to inform our future actions. It’s one or the other: A1B implies different desired actions to A2. So which George?

In

5 responses

  1. The Pedant's Apprentice Avatar
    The Pedant’s Apprentice

    “moot” in the American or British sense?

    Reply
  2. StuartA Avatar
    StuartA

    We are following the A1B emissions scenario from the SRES
    Why are you sure we are following the GHG emission curve postulated in the A1B scenario?
    Can you point me to where it’s made clear that it’s “part of Hansen’s case that we are” “tracking the A1B scenario” (Guardian site).
    That makes all of the Stern Review, based as it is upon the A2 family of scenarios, somwhat moot.
    On the Guardian site you go further:
    So what this paper is saying, amongst other things, is that the Stern Review was actually wrong.
    Monbiot does not mention the Stern Review in the article to which you link. Where does Monbiot use the Stern Review, and in particular its assumption of the A2 scenario, to “inform our future actions”? The closest I can find is a pre-publication reference to African climate change, based on an article in The Independent, and presumably not made in the knowledge of the A2 scenario basis of Stern. Where, then, is the contradiction? Where has he failed to choose “one or the other”?
    Monbiot has criticised the Stern Review, saying that it does not prescribe sufficient GHG reductions to avert the dangerous climate change predicated on the A2 scenario. If that’s so, then his proposed reductions might well still be valid even if they were based on A2 via Stern, and even if the A2 scenario had been somehow invalidated by Hansen et al — neither of which you have yet convincingly shown.
    Finally, while adopting what you claim is an implication or contention of the paper (that we are following A1B), you entirely ignore its stated conclusions. Hansen et al. say:
    The best chance for averting ice sheet disintegration seems to be intense simultaneous efforts to reduce both CO2 emissions and non-CO2 climate forcings.
    Irrespective of Stern, and A2 scenarios, and all the rest, Hansen is not contradicting Monbiot on the need for emissions reductions.
    Hansen et al. suggested in 2006 that “the dangerous level of CO2 can be no more than approximately 450 ppm”. The new paper, they say, “makes it probable that the dangerous level is even lower”. That is, their GHG targets are congruent with Monbiot’s.
    So why are you trying to say this paper, which bolster’s Monbiot’s position, undermines it? Why are you ignoring what the paper’s authors explicitly state should be done?
    Tim adds: The A1B bit is, as I state above, on page 13 of Hansen’s paper. He charts emissions against the expected ones of A1B. They match.
    Monbiot’s assumptions about A2 etc are about his assumptions about trade, localism and globalization. As has been discussed before. A2 assumes regional and more local economies, A1 more globalization.

    Reply
  3. StuartA Avatar
    StuartA

    The A1B bit is, as I state above, on page 13 of Hansen’s paper. He charts emissions against the expected ones of A1B. They match.
    I saw the plots. However, they do not allow your conclusion. They show observed emissions up to the present day matching the beginning of the A1B curve. But they also match Hansen et al.’s “alternative scenario”. In the text, also on that page, the authors state that “[i]t is difficult to discriminate among CO2 scenarios, because they diverge gradually.” Presumably for this reason they do not pronounce on which scenario we are following. In absence of a comparable plot against A2, it is plainly not possible to discriminate between it and A1B.
    Yet you are apparently certain that we are following A1B. You appear to be trying to attribute this claim to Hansen et al. Indeed, you allege it is “part of Hansen’s case”. But you have not said where the authors rely on this assumption, which as far as I can see they never make explicit, and which has no bearing on the main subject of their paper: paleoclimatic data on climate change feedback. So I repeat: how can you be so certain we following A1B?
    Monbiot’s assumptions about A2 etc are about his assumptions about trade, localism and globalization. As has been discussed before. A2 assumes regional and more local economies, A1 more globalization.
    Please point me to the discussion where you show that Monbiot assumes A2 emissions on the strength of the Stern Review. Because if he doesn’t, then I fail to see the contradiction with his use of the Hansen et al. paper (which is about the effects of GHGs, not “trade, localism and globalisation”).
    And of course, in the background, you are ignoring Hansen et al.’s basic contention regarding the dangers of GHG emissions (if true it demolishes your plan for economic growth unrestricted by emissions targets), as well as the fact that their emissions targets are close to Monbiot’s.
    Tim adds: “if true it demolishes your plan for economic growth unrestricted by emissions targets”
    That’s not what I argue for at all. Stern stated that we should take care of the economic well being of our descendents. It’s difficult to argue with that point, to be sure. So I don’t. What I do is look a the economic assumptions made by the SRES and try to see which policy mix leads to the greatest economic welfare of our descendents. That’s the A1 family. The one with more globalization.
    I’ve also said that you can have emissions limitations (my preference would be a carbon tax) on top of that as well: but if future economic welfare is to be, as per Stern, what we judge matters by, then clearly, we must indeed judge matters by future economic welfare.
    Monbiot, probably without realizing it, continually argues for less globalization and thus a move to the A2 policy mix: something which provides a great deal less future economic welfare.
    There’s absolutely nothing at all in my arguments about these various policy mixes that even implies, let alone states, that economic growth should be “unrestricted by emissions”, targets or not.
    Rather, let’s follow the policy mix, as Stern urges us to, which provides the maximum future economic welfare, then add emissions control on top, if we should so wish.

    Reply
  4. Pete Avatar
    Pete

    Does this mean that George will be selling the car he bought a few weeks ago?

    Reply
  5. StuartA Avatar
    StuartA

    What I do is look a the economic assumptions made by the SRES and try to see which policy mix leads to the greatest economic welfare of our descendents. That’s the A1 family. The one with more globalization.
    We have been over this. The SRES explicitly does not tell anybody “which policy mix leads to the greatest economic welfare of our descendents”.
    It says, of those scenarios:
    No judgment is offered in this report as to the preference for any of the scenarios and they are not assigned probabilities of occurrence, neither must they be interpreted as policy recommendations.
    I pointed this out some time ago. You have again ignored it.
    You have also ignored the glaring problems with your latest foray. You haven’t said where Monbiot assumes A2 emissions. You haven’t said why the emissions cuts he advocates are wrong even though they accord with Hansen et al.’s. You haven’t said where Hansen et al. assume A1B. You haven’t said how Hansen et al.’s plots allow one to isolate A1B as the scenario we are following. Above all, you haven’t said how we can ignore the possibility, raised in the paper to which you have applied your unique hermeneutical talents, that we are already past a dangerous level of CO2.
    Why, given all this, should anyone take your pronouncements on climate change remotely seriously?

    Reply

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