Heliophage


Head count
October 20, 2013, 10:21 am
Filed under: Books, Media

Elizabeth Kolbert has an interesting book review on population, with a nitrogen lede, at The New Yorker. It mentions in passing an assessment that nitrogen fixation added two years to the length of the first world war. I’ve heard similar broad claims but would be interested in more detailed analysis; perhaps some is provided or referenced in Alan Weisman’s “Countdown” (Amazon UK|US), one of the books under review.

The review’s a  run through some current anti-natalism and pro-natalism books. The context is the twentieth-century population growth allowed by Haber-Bosch nitrogen fixation and its continuation, abatement or reversal, and the fight between malthusians and cornucopians, though she doesn’t really pick a side on that. She acknowledges that malthusianism ahas so far been wrong, but not that it has to be.

Weisman is the anti-natalist, and fits my general stereotyping by being a man in his sixties (rule of thumb: when in an environmental conversation that has previously not been about population someone declares that the fundamental problem is population, but no one wants to talk about it, that someone will be an older man). Apparently he thinks that about 2 billion might be a “natural” population level and that this century will determine an “optimal” level for population (which from the context might be the level supportable after a large scale die off). It sounds as though I should probably look at this book, though I doubt I am going to enjoy it.

A little nit-picking. For those of us with an interest in photosynthesis (and if you don’t have such an interest, I have a book to recommend a book to you….) the idea that, thanks to Haber-Bosch. you and I “are eating bread made of air, and so, in a sense, are made of air as well,” draws a smile. Where does she think the rest of the bread comes from, if not from the air? I also think it’s a trifle unfair to give the impression that William Crookes was a straightforward malthusian when he specifically noted that chemical technology could and should solve the crisis of fertiliser supply that he saw coming. And while it’s her call to quote E O Wilson calling human population growth as “more bacterial than primate” (a quote she’s used before) equating humans with pestilence in that way always sets my teeth on edge.

I also note that Jonathan Last, author of “What to expect when no-one’s expecting” (Amazon UK|US) has some issues with the way the review treats his arguments.

Update: In a curious anti-natalist synchronicity, “Don’t have any more Mrs Moore” came on the radio just as I posted this… (Courtesy of Jeremy Hutchinson on Desert Island Discs)



Oscars 2014: Metaprediction
August 23, 2013, 12:49 pm
Filed under: film, Media

I notice that the Oscar prediction season has started. I can understand why this is of no interest to many sane people, but I quite enjoy it. And I may enjoy it even more this year (though that will depend to a certain extent on the movies…) This is because last year, as I blogged, the excellent Kris Tapley told his podcast sparring-partner Anne Thompson that “There’s no way to Nate Silver this kind of thing” — and this year Nate Silver plans to Nate Silver not just this kind of thing, but the thing itself.

His track record is held by some to suggest that he won’t do very well. But it seems to me that the way to measure his predictions is not against the outcome per se, but against other people making predictions, such as those pooled together at the Gurus o’ Gold site. Last year the statistical model put together by Ben Zauzmer did better than half the gurus and not as well as the other half, though this was because he felt there was insufficient data to call some of the races: on the races he called, Ben did as well as one of the better gurus. I suspect that, with more experience, more resources and quite a strong incentive to shine Nate Silver may do better than Ben.

So my metaprediction is that, if Silver chooses to predict all of the races, or a large majority of them, he will beat most of the gurus, but not all of them; the best of the gurus will do better. My further prediction is that if he keeps it up over five years, no single human predictor will beat him continuously.

And while I am at it, I predict that the predictinator will predict that Gravity will win the special effects oscar — and that it will be right.

 



How the IPCC glaciers paragraph was reviewed
January 25, 2010, 6:01 pm
Filed under: Media

On the subject of the glacier claims in the Asia chapter of Working Group II’s contribution to the fourth assessment, here’s what was said in the review process (relevant pdfs here) about the passage with the 2035 disappearance figure and the 500,000 km^2 to 100,000 km^2 area reductions. The nearest thing I can see to a direct criticism comes from the Japanese government. It concentrates on confidence rather than on source but obviously the two are linked.

This seems to be a very important statement, possibly should be in the SPM [summary for policy makers], but is buried in the middle of this chapter. What is the confidence level/certainty? (i.e.“likelihood of the glaciers disappearing is very high” is at which level of likelihood? (ref. to Box TS-1, “Description of Likelihood” [this is where qualitative descriptions of likelihood are equated to quantitative statements of probability, with “very likely” meaning >90% probability). Also in this paragraph, the use of “will” is ambiguous and should be replaced with appropriate likelihood/confidence level terminology.

The response to this was “Appropriate revisions and editing made”.

Wong Poh Poh, of the National University of Singapore, asked for some more detail

Table 10.10. Provide examples of rates of retreat of glaciers outside Asia (e.g. Alpine, Arctic) to show that Himalayan glaciers are indeed receeding faster.

Response: “Revised the section”.

Two points on the sentence “Its total area will shrink from the present 500,000 to 100,000 km2 by the year 2035.” from David Saltz of the Desert Research Institute, Ben Gurion University

What does ‘its’ refer to?

100,000?  You just said it will disappear.

Answers “glaciers” and “Missed to clarify this one”

There are also a number of review comments from Hayley Fowler of Newcastle University, drawing on her own research on water availability and teh broader literature, such as this one.

I am not sure that this is true for the very large Karakoram glaciers in the western Himalaya. Hewitt (2005) suggests from measurements that these are expanding – and this would certainly be explained by climatic change in preciptiation and temperature trends seen in the Karakoram region (Fowler and Archer, J Climate in press; Archer and Fowler, 2004) You need to quote Barnett et al.’s 2005 Nature paper here – this seems very similar to what they said. “

Response “Was unable to get hold of the suggested references: will consider in the final version”: In the finished product, as far as I can see, Archer and Fowler are quoted (as they were in the second order draft), Hewitt, Fowler and Archer and Barnett et al are not.

Clair Hanson, who was at the time part of the technical support unit for WGII, raises the lack of references in various sections of the Asia chapter (Dr Wong raises a similar point, as does Mick Kelly of UEA). The response was “more references added”.

This last bit may be crucial. Up until the second order draft, there was no reference at all for the problematic paragraph on glaciers; the reference to the WWF report was added later, and thus rather at the last minute. This fits pretty well with the idea that the original source was the Down to Earth article, which contains things that are there in the IPCC report but not in the WWF article. Apart from the addition of that reference, the only other changes to the passage during the editing process, as far as I can see, are cosmetic, and do not really correspond to the replies made to the people who commented during the review. “About 15,000 Himalayan glaciers form a unique reservoir which supports perennial rivers such as the Indus, Ganga and Brahmaputra which, in turn, are the lifeline of millions of people,” in the first draft becomes rather more exactly “About 15,000 Himalayan glaciers form a unique reservoir which supports perennial rivers such as the Indus, Ganga and Brahmaputra which, in turn, are the lifeline of millions of people in South Asian Countries (Pakistan, Nepal, Bhutan, India and Bangladesh)”. “The earth keeps getting warmer” becomes “The earth keeps warming”. And a sentence that adds drama but not information, ” The glaciers will be decaying at rapid, catastrophic rates,” is dropped.

So no one specifically said the claims about the glaciers are wrong. But they did raise some other points to which, apparently, little heed was paid.



Why people disagree about geoengineering
October 26, 2009, 11:08 am
Filed under: Geoengineering, Media, Uncategorized

Steven Levitt, at the end of a long post on his freakonomics blog about Superfreakonomics and geoengineering:

For all the blogosphere shouting against our chapter, I have to be honest and say that I just don’t get it. I can’t understand why any environmentalist who really cares about the Earth’s future could say with a straight face that geoengineering doesn’t deserve a seat at the table as the global-warming debate heats up.

This mischaracterises the debate/furore/ritual clubbing/whatever (see previous posts). Quite a lot of the people attacking superfreakonomics — eg Brad Delong — *do* want geoengineering to have a seat at the table. It’s just that they don’t like the superfreaks’ treatment of the subject — and may, as I do, think such treatment is going to make it harder to get that seat, not easier. They, and I, are criticising the chapter not because geoengineering shouldn’t be taken seriously, but because Levitt and Dubner don’t seem to be trying to take it seriously: their handling of the issue  is partial and unsatisfactory. It mixes a poorly tempered enthusiasm for geoengineering with some tired tropes of global warming denialism (which serve no clear purpose in the argument), and it frames the idea specifically as an alternative to emissions reductions (“Mt Pinatubo versus Al Gore”, “solve the whole global warming problem”) rather than as an additional strategy should there be a need for prompt cooling.

From the evidence of his post Levitt sort-of-gets some of this: that is why he says that the chapter in question is really about “how could we most efficiently cool the earth fast”, rather than other questions such as “how can we most equitably manage the risk of climate change”. But: a) while it may well be that a close reading provides textual support for the idea that the superfreaks acknowledge the narrow focus of their question, the chapter sure gives the impression that it is about climate change in general; b) asking “how can we most efficiently cool the earth fast” without asking broader questions about climate change is intellectually shallow; c) even in the narrow frame, surely “how could we most efficiently cool the earth fast and keep it cool” is a better question, with a more complex answer.

Generosity dictates, though, that we should also look more generally at the real phenomenon that Levitt points to: people who don’t want geoengineering discussed at all, or only under the strictest of limits. I disagree with these people. But I don’t find it very hard to understand where they are coming from. Here are five components to their arguments, as I see them.

  1. Geongineering adds to the climate risks unconscionably. Volcanoes, and by implication other stratospheric-veil schemes, screw with hydrology; cloud brightening can change ocean currents; ocean fertilization radically rearranges ecosystems: we don’t know how to do any of these things well, and if we sanction the general idea that geoengineering is plausible we are prohibitively unlikely to retire all these risks before going ahead with a scheme. As applied to geoengineering research this is partly an epistemological argument (the impossibility of getting knowledge of a high enough quality) and partly a slippery slope argument. I think in general slippery slope arguments are overblown, but I can see where this line of reasoning is coming from. (There is also a linked concern about crowding out research money for other aspects of climate, but I think that’s a sceond tier argument)
  2. It is reasonable to distrust a priori the motives of anyone who tries to argue for any approach to global warming other than emissions reduction. People feel this because they know, from experience and analysis, that that there are extremely powerful lobbies which want to slow or derail emissions reduction, and assume that pretty much anyone saying anything along those lines is doing so as either a dupe or a tool of those lobbies. There is an element of cognitive miserliness in this; but where one person says cognitive miser another might say cognitively prudent, and ask why he or she should bother wasting cognition on a subject when past experience has given them a pretty damn good inductive basis for thinking such an investment of thought will be wasted.
  3. I think its clearly true that many environmentalists have a pre-existing desire for people to live low-impact, low-consumption lives, often because they sincerely believe that this will make everyone happier. To some extent, and with various levels of awareness that they are behaving in this way, some of these people see concern about global warming as an instrumental way to bring a low-consumption low-impact work of some sort about. This is not to say they are insincere in their concern about global warming: merely that it is overdetermined. I personally would rather people separated out these two strands of their thought, but I can see as a matter of fact that they frequently don’t, and I’m sure if Steve Levitt was really trying to “get” things he could see that to.
  4. The first moral argument. At an everything-I-need-to-know-I-learned-in-kindergarten level people think that when you make a mess you should clean it up, not paint over it, even if painting over it is much easier. This is not a particularly good argument, and will have little if any traction with people who see the world in terms of costs and benefits — but it is an argument that people can feel easily and clearly, and feelings about the morality of pollution run deep.
  5. The second moral argument: the purpose of environmental action is to restore nature. This means getting back to a preindustrial sort of a climate, with lower greenhouse gases and no permanent high-altitude smogs. For me, this is a flawed argument, a planet-wide application of the naturalistic fallacy; I think correct environmental action is much more complex, and that increasing the possibilities for human happiness matters more than an idealised concern for nature. But I understand that other people don’t feel this way.

There is doubtless more to geoengineering opposition than this, but these five points seem to me to cover a great deal of it. The important thing is to grasp that geoengineering is at some level just another form of climate change, that there are a great many of ways in which people disagree about climate change, and that it helps to understand them. If Steven Levitt wants to understand all this better, then he ought to buy a copy of  Mike Hulme’s “Why we disagree about global warming” (Amazon US|UK), as discussed in the Copenhagen reading list post.

PS: Recent useful contributions to the superfreakonomics debate: an interview with Ken Caldeira by Jeff Goodell, whose book on all this is going to be way better than Superfreakonomics, and Daniel Davies on what contrarians should expect.



More superfreakonomics
October 19, 2009, 5:03 pm
Filed under: Geoengineering, Media

Little of science or policy import in this post: mostly process.

Brad DeLong (all right one more i gotta correct the record) has used the Google cache to come up with pretty clear evidence that, pace Dubner (who may have been misinformed), there was originally a look-inside-the-book option for Superfreakonomics which has subsequently been withdrawn.

Joe Romm (anatomy of a debunking) posts quite a lot of correspondence with Ken Caldeira, some of which was in Dubner’s earlier post. One specific point to stress: Ken is in this email as elsewhere very clear that he supports geoengineering research and not geoengineering implementation under current conditions. That crucial subtlety does seem to be missing from the Superfreakonomics account of his work. In general, reading this through, it seems to me that my impression of the chapter last night is one I broadly still hold.

Paul Krugman looks at some lessons learned and points well enunciated in superfreakingmeta.

I note, by the way, that Google is currently of the opnion that no-one is using the term superfrakonomics, or for that matter superfrak’donomics. Given the number of BSG fans in the better parts of the blogosphere this surprises me…

Those interested in more on geoengineering from this blog, rather than a load of links to today’s controversy, might want to browse further in the geoengineering category; a nice start is this post and the article it links to, and the IMO post is quite fun too.

Update: missed this, an email exchange with Superfreakonomics author Steven Levitt. He doesn’t really get some of the issues, but does say:

I do think also that there is something to be said for raising some skepticism about the current climate models and predictions…they are stated and restated as if they are fact, when in practice I suspect, and good scientists agree, that there is enormous uncertainty and things we cannot or at least could not know.

Probably, though, our message on geoengineering would have come through better if we had written the chapter differently.



Superfreakonomics, etc
October 18, 2009, 8:57 pm
Filed under: Geoengineering, Media

[Updated Monday morning to include Brad's last post and Gavin's take on Real Climate, an update I take note of up here because they're both worth your time: More in subsequent post Monday pm]

As someone interested in geoengineering, and writing about it myself, I look forward to actually reading what Levitt and Dubner say on the subject in Superfreakonomics (Amazon US|UK) (you can download a copyright-challenged scan of the chapter here as of the time of writing). Once I’ve done so I may, if so moved, comment on it further, but I’ll try to keep this short [update: as you can see from the bottom of this post I did read it -- and at the time of posting the xkcd cartoon at the top looks more apposite than ever]. From what I can gather: a) they make a case that geoengineering is a serious option and should be considered as such; b) they do so in a way that spectacularly fails to convince — and indeed enrages — a lot of people who are of a different opinion on this matter, partly because some of their material seems to be the sort of thing that denialists/sceptics/whatever say a lot, and wrong. Anyway, because I feel I should post something, I haven’t read the material and don’t really want to get into this in depth right now, here is a guide to what’s out there for those who want to track it.

Outrage central (how surprising) is Joe Romm’s Climate Progress. Gists follow (nb there’s a fair amount of overlap and repetition):

Post one: Seeing belief in climate change as being akin to religion is wrong, economics not a science, Nathan Myrhvold not all he’s cracked up to be [not fully convinced by JR on this]; Ken Caldeira, a major source for the relevant part of the book, feels misrepresented. This post originally came with a pdf of the chapter, but the publishers asked for it to be removed. It is also apparently the most trafficked post on Climate Progress this year

Post two: Evil geoengineering ideas of Myrhvold’s have corrupted Bill Gates and Warren Buffett; Pinatubo cooling, which lasted for a year or so, does not validate the idea that permanent stratospheric sheidls might do better.

Post three: Amazon feature that allows you to read relevant pages of the book has been disabled. Superfreaks wrong to say the world is cooling now, and that it was feared to be cooling catastrophically in the 1970s. Union of Concerned Scientists lists problems with the climate science in the chapter.

Post four: Superfreaks have denied be “deniers” — but JR has not accused them of this. Superfreaks appear, as Paul Krugman has pointed out, to have mischaracterised/misunderstood Martin Weitzman’s argument about catastrophic risks in the low probability part of the climate sensitivity distribution.

Post 5: Outsourced in large part to Brad Delong (see below). Disputes Dubner’s claim that the book was never readable on Amazon.

There will be more from Joe over the next few days. Dubner’s main response to critics (there was an earlier I-am-not-a-denier placeholder) came out after the fifth of these posts. Gist of the main post: Not a denialist. Disputes some of Joe’s specific points, promises more to come on some, notes Joe’s ideological stance. Key point: Ken Caldeira saw the draft twice, was asked for comments, mostly didn’t object. Quotes Ken in an email to Joe and since forwarded by Ken to Dubner:

I f&@?ed up. They sent me the draft and I approved it without reading it carefully and I just missed it. … I think everyone operated in good faith, and this was just a mistake that got by my inadequate editing

In a later email Ken expanded on his interactions with Romm

Rather than acting deliberately, I panicked and commented on things that I now wish I would have been silent on. It was obviously a mistake to let myself get drawn into this, and I learned a quick and hard lesson in public relations.

Dubner goes on to say that the relevant text was never searchable on Amazon. Its noticeable that this post focuses entirely on Romm, treating him as fons et origo of all other criticism. It doesn’t address the fact that the chapter has also been criticised by economist and colleague on fellow New York Times blogger Paul Krugman. Gists:

Krugman post 1: I trust Joe Romm, and I worry that superfreakomics guys love contrarianism for the sake of it. Fate of the planet too important for that.

Krugman post 2: Starting off with the global-believed-in-the-1970s story cuts credibility. They missed the point of Weitzmann’s analysis.

Krugman post 3: More on what Weitzmann actually said. Notes Dubner’s not-a-denialist post, doesn’t think it cuts it.

Elsewhere

William Connelly (Stoat):

Diagnosis, in brief: (1) they write about stuff they clearly don’t understand (2) they pick a catchy reverse-common-wisdom nugget as a headliner without the having the slightest interest in whether it is true or not

William also offers chapter and verse on global cooling and other rhetoric borrowed from skeptics that the superfreaks use (rather confusingly, since they and their sources genuinely don’t seem to be deniers). He also has excellent taste in cartoons.

Tim Lambert (Deltoid):

Levitt and Dubner do not understand the climate science literature. This by itself would not be fatal, but what has taken them off the cliff is the Freakonomics formula: “What you thought you knew about X is wrong!”

There follow some mostly good points, made more concisely than Joe Romm does.

Brad Delong has taken various shots on the subject. Here is an exchange of emails with Dubner, and here are six specific questions. He also helpfully points readers towards 4 more favourable blog posts on the book from Bryan Caplan:

Overall, [the book]‘s better than the original.  It’s still cutesy, but stronger in the “who cares?” factor.

Tim Harford:

[The geoengineering chapter] is a strong story, but it is also one-sided, portraying the geo-engineers as brilliant iconoclasts, dismissing the objections to geo-engineering as the knee-jerk reaction of the unreflective, and failing to convey the views of a single credible geo-engineering sceptic. A well-deserved swipe at Al Gore does not really count.

Joshua Gans:

There is nothing too wrong with [the geoengineering chapter]. Not enough for name calling. What the authors are doing is identifying the ‘economist’s angst’ in this whole discussion.

and Robert Waldmann

As far as I can tell, [the superfreaks' critics] really don’t have very much to say against [geoengineering]. Rather they mainly object to the Steves’ proposal that we use [it] as an alternative to cap and trade. The argument against doing both seems fairly weak to me.

[Update: Then, in the optimistically entitled *sigh* last post on superfreakonomics I promise, Brad gives a full list of issues he and others have with the chapter (you need to have the pdf or a copy of the book to go through these properly). This is probably the best single place for a list of the problems that have been raised. His take home message:

It really does look to me like Levitt and Dubner:

  • went to Myhrvold's Intellectual Ventures.
  • got wowed.
  • excitedly wrote up what they heard.
  • and then failed to do their intellectual due diligence about what they were told there.]

[Further update: Gavin has a post at Real Climate, which tends towards the straw-mannish, in that it suggests that geoengineering might be treated as a strategy for a world with no emission reductions, which I don't think many people, if any, are really advocating (though people might argue it could come about anyway). But it is definitely worth reading. And it points to this very good post on the topic by Michael Tobis, which puts geoengineering, mitigation and adaptation into the context of interventions which are not mutually exclusive -- a good place to put them]

Ezra Klein looks at other aspects of the book and the authors’ MO

The problem with Super Freakonomics is it prefers an interesting story to an accurate one. This is evident from the very first story on the very first page of the book.

After all this I gave in and skimmed the chapter. It has some interesting discussions in it, but I think quite a few of the criticisms are well founded: there are what I take to be some errors,  some suggestio falsi, and some serious omissions.  I think there’s a structural delight in the contrarian which gets irksome, and I think building your understanding of geoengineering out of what is heard at an Intellectual Ventures meeting is not likely to give you a fully rounded view of the issue. I wish they had gone deeper. That said I am not convinced by all the criticisms, and I do think wider discussion of geoengineering — and indeed frank advocacy — is something to be hoped for. People need to say what they think should be done.

That said, last word for now to dsquared’s take on freakonomics in general:

My intuition is that Freakonomics has had its moment in the sun. The central selling point was always, basically, academic machismo; the presumption on the part of economists that because they were “smart” in the Larry Summers sense, they could turn their hand to anything and the rest of the world was bound to listen to them. Those days, to put it mildly, are gone.

Image from the wonderful xkcd, used under creative commons licence



Pen Hadow isn’t news
October 15, 2009, 9:59 am
Filed under: Global change, Media

Yes, its melting

Yes, it's melting

Having been a little disobliging about Pen Hadow, an explorer, in a previous post about “Heroes of the Environment” I now feel moved to return, briefly, to the subject. This morning the BBC is putting data gathered during Hadow’s recent Arctic adventure — a trek with two companions, called the Catlin Arctic Survey, that was meant to get to the North Pole but didn’t — into its main radio news bulletins at the moment. As Professor Peter Wadhams of Cambridge puts it in the BBC’s online version of the story and many other places:

The Catlin Arctic Survey data supports the new consensus view – based on seasonal variation of ice extent and thickness, changes in temperatures, winds and especially ice composition – that the Arctic will be ice-free in summer within about 20 years, and that much of the decrease will be happening within 10 years.

Which seems fine: but not news. What we have here is a consensus for which, because it is a consensus, we must assume there is already a lot of evidence, being backed up by some incremental unpublished data (pdf of science findings) that will later be presented at the Copenhagen meeting and submitted to Cold Regions Science and Technology, a journal I am pretty sure that the BBC does not often use as a source. What Wadhams says seems true and sensible, but reporting stuff that is widely accepted as news doesn’t.

To be fair, the BBC further reports that

Pen Hadow admitted that the expedition had not led to “a giant leap forward in understanding” but had been useful as an incremental step in the science of answering the key questions about the Arctic.

but it doesn’t go on to say why it reports this incremental step. The answer, obviously, is that it thinks the public likes explorers, and will find science done by explorers interesting, even if the equipment broke down and the observations are not yet of any proven value; it also probably thinks that raising awareness about global warming is a good thing. Personally I find people who “explore” a planet that has already been pretty thoroughly explored  and do so in deliberately over-challenging and attention-seeking ways (Hadow first came to fame walking to the North Pole on his own without resupply) a little off-putting, even, in my more misanthropic moods, distasteful, though on the only time I met one he seemed a nice enough chap (that said, we were both talking to Edwina Curry, so contrast may have had something to do with it). If such people want to try to contribute to science and advertise a reinsurance company as they do so, fair enough (though the apparent shennanigans with data on their website suggest that this most recent undertaking was not utterly rigorous in its approach). But following HRH the Prince of Wales, who says this is a “remarkably important project”, in treating this data gathering as news seems to be a pretty straightforward mistake, even before you get on to the mistakes in headlining that “news”, such as “North Pole ice cap gone in 10 years“.

The generally grumpy tone of this post, and the unaccustomed act of linking to Watts, brings to mind a point a friend recently made to me — that I am more critical of  climate-change claims that tilt beyond science into propaganda in private than I am in public. I think that to the extent this is true it is only because most of what I do in public isn’t about that sort of thing; I don’t spend much time attacking climate sceptics in public, either, and that certainly shouldn’t be seen as suggesting support. But while I am tapping away I will take this opportunity to say that I think people who talk about a climate sensitivity of more than 4ºC as remotely likely need to  explain why they think this when others such as James Annan have argued well against it*. And I think when people talk about multi-metre sea-level rises, as  Jonathan Porritt did on Radio 4 recently (“I have increasingly less time for those whose nimby-ist sentiments persuade them that somehow the best route to defending their cherished landscapes is by letting it be drowned by a huge amount later on in life. Which particular bit of the landscape do you want to defend James if what we’re threatened by is a seven metre rise in sea levels? ” — rtf transcript), they need to make clear that they are talking about the situation that’s not “later on in life” for anyone who doesn’t expect to live for a few centuries.

*hint: explanations that include phrases such as “I don’t use the classical Charney measure of sensitivity because I think one also has to take into account biosphere and other long-term feedbacks to which it pays no heed” seem to me to be headed in a plausible direction; I may also show sympathy to “unlikely events in the long tail dominate the risk assessment”, though rather less so…

Not terribly relevant image from A Davies/Greenpeace, used under a Creative Commons licence




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