economist-20130330_LDC346 The Economist is read by all the most Important People (what, you say you don’t read it? Well…), so what they say about GW matters (even if they sometimes talk twaddle it still matters). What they are currently saying under the byline “Climate change may be happening more slowly than scientists thought. But the world still needs to deal with it” is

some scientists are arguing that man-made climate change is not quite so bad a threat as it appeared to be a few years ago… “climate sensitivity”… may not be as high as was previously thought. The most obvious reason is that, despite a marked warming over the course of the 20th century, temperatures have not really risen over the past ten years. It is not clear why climate change has “plateaued” (see article). It could be because of greater natural variability in the climate, because clouds dampen warming or because of some other little-understood mechanism in the almost infinitely complex climate system. But whatever the reason, some of the really ghastly scenarios—where the planet heated up by 4°C or more this century—are coming to look mercifully unlikely. Does that mean the world no longer has to worry?

No, for two reasons. The first is uncertainty. The science that points towards a sensitivity lower than models have previously predicted is still tentative… The risk of severe warming—an increase of 3°C, say—though diminished, remains real. There is also uncertainty over what that warming will actually do to the planet. The sharp reduction in Arctic ice is not something scientists expected would happen at today’s temperatures. What other effects of even modest temperature rise remain unknown?

The second reason is more practical. If the world had based its climate policies on previous predictions of a high sensitivity, then there would be a case for relaxing those policies… But although climate rhetoric has been based on fears of high sensitivity, climate policy has not been…

So, that’s all pretty good, even if you don’t like “plateau”.

The linked article sources Ed Hawkins pic. And apparently Work by Julia Hargreaves of the Research Institute for Global Change in Yokohama, which was published in 2012, suggests a 90% chance of the actual change being in the range of 0.5-4.0°C, with a mean of 2.3°C. Nic Lewis gets a mention for an unpublished paper. And then my eyes rather glazed over, because it was more of the same old stuff, ending up with

So what does all this amount to? … a small reduction in estimates of climate sensitivity would seem to be justified: a downwards nudge on various best estimates from 3°C to 2.5°C, perhaps; a lower ceiling (around 4.5°C), certainly… global temperatures rise by about 1.5°C for each trillion tonnes of carbon put into the atmosphere… At current rates, the next half-trillion tonnes will be emitted by 2045; the one after that before 2080… this could increase temperatures compared with pre-industrial levels by around 2°C even with a lower sensitivity and perhaps nearer to 4°C at the top end of the estimates. Despite all the work on sensitivity, no one really knows how the climate would react if temperatures rose by as much as 4°C. Hardly reassuring.

Refs

* The melting north
* How The Economist got it wrong – by DANA NUCCITELLI AND MICHAEL E MANN

Comments

  1. #1 Victor Venema
    2013/03/29

    The Economist deserves a price for its most creative x-axis.

  2. #2 James Annan
    http://julesandjames.blogspot.jp/
    2013/03/29

    Might have to start getting the Economist if it is going to make sense. Good to see Reto putting the brakes on progress…

    [Are you not wildly jealous that Julia gets a mention but not you :-? -W]

  3. #3 Steve Bloom
    2013/03/29

    And Lewis a “climate scientist” to boot.

  4. #4 James Annan
    http://julesandjames.blogspot.jp/
    2013/03/29

    Incidentally, you sound like the sort of person who reads the Times – if so, any chance you (or one of your readers) could send me the text of this Ridley article? I heard it cited me, but I don’t know if it was reasonable, dubious, or Rose-esque.

    http://www.thetimes.co.uk/tto/opinion/columnists/article3723862.ece

    [Not me, but my father in law does. Your bit is We may well get that increase, even though there’s been no net global warming now for 16 years and the latest peer-reviewed studies (from James Annan of the Japan Agency for Marine-Earth Science and Technology, Magne Aldrin of the Norwegian Computing Center and Michael Schlesinger of the University of Illinois, among others) all confirm that the climate is less sensitive to carbon dioxide than the IPCC has been saying. Still, at least he's, errm, "quoting" you not Julia :-) -W]

  5. #5 blueshift
    2013/03/29

    Is a lower bound of .5C believable?

    [You mean, you think it might be lower :-? -W]

  6. #6 BBD
    2013/03/29

    Interesting use ‘confirm’ in that Telegraph quote. Perhaps ‘suggest’ might have been a little less… loaded.

  7. #7 BBD
    2013/03/29

    From the Economist article:

    That sounds reassuring: the TCR is below estimates for equilibrium climate sensitivity.

    I’m not surprised your eyes glazed over.

    Nic Lewis, an independent climate scientist, got an even lower range in a study accepted for publication: 1.0-3.0°C, with a mean of 1.6°C.

    I thought NL was a ‘semi-retired financier’ or something similar. Nor did I know that his blog post at Bishop Hill had been accepted for publication. If this is correct, it will be interesting to see what the reviewers make of NL’s submission.

    A recent paper by Ka-Kit Tung and Jiansong Zhou in the Proceedings of the National Academy of Sciences links temperature changes from 1750 to natural changes (such as sea temperatures in the Atlantic Ocean) and suggests that “the anthropogenic global-warming trends might have been overestimated by a factor of two in the second half of the 20th century.”

    Not everybody is happy with T&Z though, are they? Unfortunately, this got overlooked by the subs ;-)

  8. #8 freddy
    2013/03/29

    Economist “… it could be because of greater natural variability in the climate, because clouds dampen warming or because of some other little-understood mechanism in the almost infinitely complex climate system …”

    This is by far the most lucid analysis from main stream press since quite some time. Negative cloud feedback, little-understood mechanisms, almost infinitely complex climate system, natural climate variability: it may well be that anthropogenic CO2 has NO measurable effects in air temperatures in the next decades.

    [Care to put your money where your mouth is? -W]

  9. #9 OPatrick
    2013/03/29

    Are you, or James Annan since he’s here, concerned by the only very brief mention and perhaps dismissal of the deep ocean temperature data, as Dana picked out at SkepticalScience?

    [The deep ocean stuff seems quite new. I'm not surprised the Economist ignored it; presumably we'll hear more about it in time -W]

  10. #10 OPatrick
    2013/03/30

    But their argument does seem to include other new studies, and indeed some that aren’t even published yet.

  11. #11 MikeH
    2013/03/30

    #4

    Ridley’s article is on his blog.
    http://www.rationaloptimist.com/blog/it's-weather,-not-climate.aspx

    This is unadulterated Pielkeism. One claim caught my eye.
    “Translated: the weather is just as likely to become less extreme as more extreme.
    So why is everybody convinced otherwise? Partly because they have been listening too much to the big insurance companies, which have a vested interest in bidding up our anxiety, as Dr Pielke’s remark reminds us.”

    Well as it happens Pielke Jr is a part of the insurance industry funded Risk Frontiers group at Macquarie University in Sydney. They have produced a number of articles playing down risks associated with climate change. Here for example
    http://theconversation.com/weighing-the-toll-of-our-angry-summer-against-climate-change-12793

    Ridley should take his own advice – “Forget the anecdotes and face the facts” – he is already the “pub bore”.

  12. #12 MikeH
    2013/03/30

    More on the idiot Ridley. He also claims that

    “In 2010 Brisbane disastrously overfilled a dam because it expected drought to return; the dam could not absorb a flood when it came.”

    This is total crap sourced I suspect from reading Australian climate conspiracy cranks.

    Interestingly I found this defence of the engineers managing the dam in the comments on Pielke Jr’s own site

    … the four dedicated engineers whose privilege it was to sit up for days on end trying to work out the best strategy to control something which had NEVER been tried before – the dam was not built on the occasion of the previous flood in 1974. John Nicol, Brisbane

    Nicol is the chairman of the Australian Climate Science Coalition, a group of climate science deniers that includes Carter, Plimer etc. Would Ridley accept that as a rebuttal?

  13. #13 James Annan
    http://julesandjames.blogspot.com
    2013/03/30

    Thanks for the Ridley link (and also the text from wmc). It doesn’t look too horrible to me, at least the cite is reasonable.

    [I think that, as usual when the actual facts aren't too bad, its the tone and slant that are bad. It means that as long as you already know the answer you can read it and pick out the truth, but if you don't already know and are (heavens preserve us) reading it for information, you'll be mislead -W]

  14. #14 James Annan
    http://julesandjames.blogspot.com
    2013/03/31

    Yes, I’m afraid I’m not going to get too worked up (at least, not this time) if someone pushes back against all the hype that comes out whenever it is hot/cold/wet/dry/whatever. Of course AGW will change some of the weather, and lead to some different/bigger extremes in some sense. But there’s a lot of weather irrespective of any trend.

    Setting it up as a question of trend versus variability is a bit dodgy, because the reality is not one or the other, but both together, in uncertain proportions.

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