Should the world try to limit global warming to 2 degrees Celsius?

I’ve argued before that there seems to be a shift in the wind, in that sceptical papers about aspects of global warming are being published, and that real debate is going on at least in the blogosphere, and quick debate, too. It’s all much faster than was the case a few years ago, when the doctrine of ‘if it’s not peer-reviewed I won’t read it’ was alive and well. And here is a case in point.

Nature published a piece on the first day of this month with the provocative title ‘Ditch the 2C warming goal!’ For Nature to do this is another straw in the breeze, because it has been a bastion of the orthodoxy, and the 2C target is part of the orthodoxy. The authors, Victor and Kennel, are serious and well-credentialled, and they are not sceptics in the ordinary sense: in fact they are all about limiting emissions, but think that the 2C target is not the away to go.

Why not? First, the goal is effectively unachievable. Owing to continued failures to mitigate emissions globally, rising emissions are on track to blow through this limit eventually… Because it sounds firm and concerns future warming, the 2 °C target has allowed politicians to pretend that they are organizing for action when, in fact, most have done little. Pretending that they are chasing this unattainable goal has also allowed governments to ignore the need for massive adaptation to climate change.

Second, the 2 °C goal is impractical. It is related only probabilistically to emissions and policies, so it does not tell particular governments and people what to do. In other areas of international politics, goals have had a big effect when they have been translated into concrete, achievable actions. 

I would agree with their two principal objections, save for the notion that ‘rising emissions are on track to blow through this limit eventually’, whenever ‘eventually’ is. And ‘massive adaptation’? If it takes a century or two to teach the 2C target, I don’t think it’s much of a problem, because on the evidence a warmer world is better for nearly all living things. Incidentally, The Pause has just passed its 18th year on the RSS dataset, and various wags are wondering whether it is time for his gap year, or to buy a car, or to join the army…

Of course, an apparently sceptical piece in Nature was bound to get attention from the sceptical side, and it did so at once. At the same time, it was slammed by the bulldogs of the orthodoxy as well, which caused Victor to write a long response  at the New York Times website that is worth reading in its entirety. What comes out strongly to me is Victor’s annoyance and frustration at the dug-in defence of the orthodoxy, even when it is plain that it is losing ground, and losing effectiveness as well.

Over at RealClimate, another defensive position, Victor and Kennel’s work is dismissed: … the arguments which they present are ill-informed and simply not supported by the facts. Victor is referred to as ‘a political scientist’ and Kennel as ‘a retired astrophysicist’, as though they have no status in this debate. In fact, Victor was a Contributing Lead Author of WGIII in AR5 and is an authority on potential climate-change impacts, while Kennel was not only head of the NASA science advisory board but served as the Director of the Scripps marine sciences institution in San Diego. How dare such as they speak against the Book!

Indeed when I read all the stuff, to and fro, what strikes me most powerfully is the righteous indignation theme. That is mercifully absent on Judith Curry’s Climate etc website, and she offers an unexpected approach: So in context of the current UN framework, personally I prefer to keep 2C for now as a policy target. There is simple political reality: the pause, combined with lower sensitivity estimates, are acting to ‘kill the cause’, i.e. urgent action needed to reduce emissions. 

That is a sensitively political position for a scientist to take. Not being one, I think the 2C goal was a piece of doctrinal nonsense from the beginning. It was designed by politicians as something that could be agreed across the world, and scientists have since found all sorts of compelling reasons why it is a good thing. But this is after-the-event stuff. The 2C target has a dozen or more assumptions built into it.

And here is Dr Curry again on why, even though she prefers to keep the goal, she doesn’t like it at all: Here’s why I don’t like the 2C metric, and it has little to do with the issues raised by Victor and Kennel. The 2C metric is relevant only for the so-called linear model of decision making. Even if we had some understanding and agreement on what state of the global climate was regarded as dangerous, and we knew what to expect from natural climate variability in the 21st century (e.g. solar, volcanoes, ocean circulations), there is very substantial uncertainty in climate sensitivity to increased CO2, and hence the appropriate emissions target to avoid this level of warming. While the methods continue to be refined to determine sensitivity, none fully account for natural internal variability or for unforced ‘climate shifts’.

If you read my post last week on the Lewis/Curry paper, you’ll know why she is scornful.

All these papers are really worth reading: the original Victor/Kennel, the Victor response, the RealClimate attack, and the Curry reflections. This is one good way a climate change debate can occur. I hope we’ll get more and more, and then maybe a real, live human one in Australia, somewhere soon.

Join the discussion 13 Comments

  • Mike says:

    The trick is to announce policies at the right time, suppose David Evans has made a correct forecast. Then we need a government somewhere to implement a policy that does nothing let us say they decree a small amount of royal jelly will be introduced into fuel. Then they can declare that this will reduce the world’s temperature soon. Now suppose David Evans is correct and it goes down significantly before 2017. Everyone will remark on how effective royal jelly is. I reckon the activists saw that the world temperature was increasing and they piggybacked their aspirations onto it. The problem is the planet has become a denier or you might say a dead horse in this respect. The conundrum is where do they go from there AGW has always been a claim in which there is no understanding of its validity.

  • Walter Starck says:

    We don’t know if the 2C metric is too high or too low to avoid serious climate change.
    We don’t even know if such a change might be a net harm or actually a benefit. We don’t know how much reduction in CO2 emissions would be required to achieve this goal. We even don’t know how to achieve meaningful reductions with existing technology and there is a very real probability that future technological developments will solve the problem even if we do nothing to address it at present.

    Those who advocate drastic global action now as being essential to avoid catastrophic
    future change must either be profoundly ignorant of the scientific, technological and economic realities involved or be pursuing some other undisclosed agenda.

  • Doug Hurst says:

    Some Super Fund managers, accused of ‘unethical investments’ involving dirty coal, are hitting back, claiming that lifting hundreds of millions out of poverty with affordable electricity from coal is very ethical, and spending $1.3 trillion (yes, trillion) on renewables this past decade to provide less than 2% of world power arguably is not.

    A very well informed article in todays Financial Review made these points and others. It was especially critical of the ANU’s recent decision to take Santos out of its investment portfolio, given that Santos produces relatively clear gas and every off-shore windmill needs 250 tonnes of coking coal to produce. I can’t provide reference for the article, other than it was in today’s FR, nor can I vouch for its claims – but I can say it backs Don’s beliefs that the orthodox position is fraying at the edges more than a bit.

  • Pierre Sommerville says:

    I see you were confronted by the “formidable” Mike Hansen after you dared to comment on “The Conversation” today on an article by an academic in clear thinking, not climate science. The veritable Mike Hansen is a climate change activist of little integrity. He has posted probably 15000 times on TC. I have crossed swords with him numerous times. I caught him out manipulating the approval/disapproval system initially used by TC. I then launched into the same game, whilst pointing out to TC editors what was going on. Eventually they changed the system????. Back then Mike referred to himself as an IT specialist, which he clearly was not. Now-a- days he is but a simple “Mr”. I often wonder what he actually does for a living – he is perpetually commenting on TC.

    • Don Aitkin says:

      I don’t comment much there, because the bulldogs put up such resistance to anything other than enthusiastic agreement with the party line. But the author’s early sentence was such a clanger!

  • DaveW says:

    Makes one wonder doesn’t it? Are the powers that be afraid that global temperatures are going to drop over the next few decades? Well, they haven’t been right about anything else, so no need to assume they would be right about this. The 2C goal was always pretty silly and pegging response to climate change to increases in CO2 ppm completely uncorrelated to temperature changes seems even sillier. However, it would be pretty funny if they succeeded in changing goal posts and [CO2] started dropping.

  • dlb says:

    Are we seeing a schism within the Church of the Holy Warming?

    I gather Bishops Romm and Rahmstorf are unhappy with Bishops Victor and Kennel breaking with the 2 degree doctrine for the sign of the forthcoming apocalypse, having summoned other signs and visions for the coming doom. Such signs they decree could be foretold by an unnatural heating of the ocean and calamities such as drought and tempest to befall the land.

    Even though Victor & Kennel are true believers in alarmism it would seem they have committed the grievous sin of looking to the works of Gaia rather than following Holy Scripture as dictated by the General Circulation Models. What befalls them I’m not sure, perhaps incarceration within the borehole in the grounds of Gavin’s Abbey?

    Meanwhile to spite Pope Mannus I, heretics such as Bishop Curry and preacher Lewis have been nailing papers to the doors of peer churches saying Gaia is really a forgiving God and in no way as sensitive to our carbon sins as what the Holy Warming Church dictates. To make matters worse other learned scholars such as Lomborg and Tol think it is better to adapt to Gaia’s wrath rather than try and buy her out or commit to a monastic life of carbon abstinence.

    Finally as a sign of the times I believe a number of the church hierarchy have been having secret meetings with those evil deniers of the faith. This has provoked an outrage within the true believers and foot soldiers at Guardian Castle. Whether defenders of the faith Cook & Nuccitelli mount a crusade is yet to be seen. We live in interesting times.

    • Peter Kemmis says:

      Dear dlb

      I fear you are being a very naughty boy! And I suppose you’ll be making something out of the blogged comments below about this NASA paper, which is telling us that the deep oceans have not warmed after all.

      http://www.jpl.nasa.gov/news/news.php?feature=4321

      Jimbo October 6, 2014 at 3:15 pm

      Peter Grace, here is a quote from the Paul Durack et al paper.

      ” … the hemispheric partitioning of simulated upper-ocean warming is inconsistent with observed in-situ-based ocean heat content estimates. Relying on the close correspondence between hemispheric-scale ocean heat content and steric changes, we adjust the poorly constrained Southern Hemisphere observed warming estimates so that hemispheric ratios are consistent with the broad range of modelled results.”

      Voila! You get your desired result. So they employed models to adjust
      the observed in situ-based OHC estimates. It’s more modelled results.

      David A October 6, 2014 at 9:39 pm

      But Peter Grace quoted the author of
      the paper…“The Argo data is really critical,” said Paul Durack, a Lawrence Livermore National Laboratory researcher who led the new study, which was published in Climate Nature Change. “The estimates that we had up until now have been pretty systematically underestimating the likely changes.”
      =================================
      …estimates underestimating likely changes… How far has science fallen?
      A more accurate quote would have been …”The observations we had up till now have been well under the models predictions.”

      That would have been more honest, just as the author’s quote from
      Jimbo here of …”we adjust the poorly constrained Southern Hemisphere
      OBSERVED warming estimates so that hemispheric ratios are consistent
      with the broad range of modeled results.” could have been… The SH
      temperatures above the surface have not warmed liked the NH, thus it is
      likely that the lack of OBSERVED SH ocean warming is an accurate
      reflection of the reality that the SH ocean T has not increased as the
      models predicted, but we did not like that result, so we changed the
      data to match the models.

      (Source of comments: http://wattsupwiththat.com/2014/10/06/the-heat-went-to-the-oceans-excuse-and-trenberths-missing-heat-is-awol-deep-ocean-has-not-warmed-since-2005/) {Don, I thought these comments too pertinent not to pass on here! Do our scientists still sit at the feet of Winston Smith, learning the Newspeak language? George Orwell would be pleased!}

      • dlb says:

        Peter, as I said before one should never look to the works of Gaia when Holy Scripture as dictated by the Models of the Covenant say otherwise. Now look at the trouble Mr Darwin did to the church when he forsake scripture to look at the works of God.

  • David says:

    Don,

    Dr Curry is a climatetologist. Statements like this are normative.

    ” Here’s why I don’t like the 2C metric, and it has little to do with the issues raised by Victor and Kennel. The 2C metric is relevant only for the so-called linear model of decision making. Even if we had some understanding and agreement on what state of the global climate was regarded as dangerous, and we knew what to expect from natural climate variability in the 21st century (e.g. solar, volcanoes, ocean circulations), there is very substantial uncertainty in climate sensitivity to increased CO2, and hence the appropriate emissions target to avoid this level of warming. While the methods continue to be refined to determine sensitivity, none fully account for natural internal variability or for unforced ‘climate shifts’.”

    While she is quite entitled to make them she has no obvious expertise. Here she is wandering into the realm of the social scientist.

    • Don Aitkin says:

      She is talking about decision-making here, not about science. As I have argued, all of us in democracies are entitled to put forward our views about the decisions made by governments and the right way to make them.

      Having said that, I would have to add that many scientists see no difficulty at all in wandering into the fields of humanities and the social sciences as though their expertise in physics (or whatever) gave them real authority elsewhere. Sir Mark Oliphant was a fine example.

    • Gus says:

      “>>>Here she is wandering into the realm of the social scientist.<<<"
      In what part of the statement you quote does Judith Curry "wander into the realm of the social scientist?" She talks about considerable uncertainties of climate science, the domain of her competency. Since the science itself is so obviously un-settled and human attribution of the observed climate drift so obviously un-proven (the climate has been drifting in very much the same way and at very much the same pace since 1850, when human contribution would have been negligible, but for the past 19 years, it stopped drifting altogether!), it is obvious that any remedies proposed are un-justified, while being excessively costly and of no benefit to the society otherwise. As a climate scientist, Judith Curry is perfectly entitled to talk about the feeble foundations in this chain of reasoning, and thus question the implications drawn.

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