Thursday, December 1, 2011

Climate science as nervous system: the case Rahmstorf versus Meichsner

Today, spiegel-online and Die Welt have articles about the case Rahmstorf versus Meichsner (we had  discussed this already here). Roger Pielke jr. sums it up perfectly in proper English and the correct dose of empathy for the journalist. Still exhausted from yesterday's climategate 2 experience, reading these articles makes me feel almost sick (even the triumph of Maxeiner & Miersch in Die Welt is full of bad vibes).
When thinking about what this all might possibly mean, the anthropologist Michael Taussig comes to my mind. Taussig coined the term "nervous system", which helps maybe to  put these climate science scandals into a greater context.

 Here a nice definition of what that means:
Written in 1992, the Nervous System is an insightful anthropological work comprised of nine essays. Michael Taussig sets out on a journey to explore and describe various forces that shape and mold our present society. He tries to explore the process through which we commodify the state and in that way transfer the power to it. Taussig shows how the state uses forces such as violence or media control to consolidate its power over the people.He persuasively argues that we live in a state of emergency, citing Walter Benjamin, that is not ‘an exception but the rule.’ To show the universality of the nervous system he takes his reader through the heights of Macchu Picchu, the world of Cuna shamans, and the pale world of New York’s hospital system. (by eyal weizman)
Just add the world of climate science.
(The analogy to "the state", I am not sure about that. Things are more complex. But the general nervousness and the link to power, the wish to control the media and so on captures perfectly the inherent paranoia.)

33 comments:

Belette said...

I'm interested in the substance of all this, which isn't really clear. You haven't tried to explain it - could you?

Reading the Pielke piece, and the links therein, it looks like R complained about the journo's science - and was correct - but also complained about the journo copying - and was held to be incorrect. Is that right?

ghost said...

Interessant fand ich den letzten Absatz im Spiegel:

"
Rahmstorf indes scheint aus dem Urteil wenig gelernt zu haben. Erst am 29. November hat er in seinem Blog einen neuen Beitrag veröffentlicht, in dem er nicht nur Medien und Forscherkollegen angeht - sondern auch beklagt, dass man "in den klassischen Medien keine Kontrolle über das Endprodukt" habe."

nun, was denkt man da? Man denkt, dass Stefan Rahmstorf einen ätzenden Post geschrieben hat, der gegen Medien und Kollegen hetzt und deren Meinungen kritisiert. Das Zitat am Ende suggeriert, dass Stefan Rahmstorf, dass über alle Artikel in den Medien die Kontrolle haben will, um deren Meinung zu kontrollieren. Richtig? Findet ihr das auch?

Nun was hat er wirklich in diesem Blog-Eintrag geschrieben? Er hat geschrieben, dass klassische Medien oft, manchmal, wie auch immer, Aussagen verändern, verkürzen, entstellen. Und dass er keine Kontrolle über Endprodukt SEINER Interviews und SEINER Artikel hat. Man erinnere sich nur: das HH Abendblatt(?) hatte mal ein Zitat von Prof von Storch, obwohl er nie mit denen gesprochen hatte. War doch so?

Und "ging" er gegen Kollegen in den Eintrag "an", wie der Spiegel behauptet? Stefan Rahmstorf erwähnt nicht mal Kollegen. Er schreibt, wenn man als Klimaforscher übertreibt (was natürlich subjektiv ist ;)), steht man bald blöde dar und deswegen versucht das ALLE Kollegen zu vermeiden. Wie kommt der Spiegel darauf, dass er da Kollegen angeht?

Hier der blogeintrag, der vom Spiegel nicht verlinkt wurde: http://www.scilogs.de/wblogs/blog/klimalounge/medien-check/2011-11-29/venedig-meeresspiegel-meeresstroeme-medien

Nun allein dieser letzte Absatz zeigt, dass Stefan Rahmstorf vielleicht nicht so unrecht habt? Oder was denkt ihr oder sie?

ghost said...

Anmerkung:
Die vielen Rechtschreib- und Grammatikfehler im Text bitte ignorieren. Entschuldigung dafür.

Vinny Burgoo said...

Belette, Meichsner's article attacked a prominent claim in the AR4 Synthesis Report for being based on one rather weak non-peer-reviewed study. As the review by the InterAcademy Council found that this particular claim was almost meaningless and had a 'weak evidentiary basis' and the Dutch government's review said that it had been used misleadingly and with undue prominence and could not 'be traced back to any original scientific research' (and had been inserted invisibly after the second review), it's hard to argue that the journo got the science wrong.

She missed a trick, though. She mentioned an adjacent and related claim about Africa in the Synthesis Report but didn't follow it up: 'By 2020, between 75 million and 250 million people are projected to be exposed to increased water stress due to climate change.' This claim wasn't just misleading but straightforwardly erroneous. Its originator, Nigel Arnell, has admitted that he got his stats wrong and that the 'correct' range should have been between 90 and 220 million. Correct or not (it can't be derived from the data in his paper), that range is very misleading. It takes no account of the substantial African populations that his study said would be exposed to reduced water-stress - that is, the range is gross, not net.

(The 'between 75 and 250 million' claim is very popular in some quarters. Christian Aid changed 'water stress' to 'poverty', dropped the lower bound and used it in an ad campaign in the run-up to COP15. Although it was debunked several years ago, Dr Pachauri continues to trot it out every few months, most recently on Wednesday in Durban.)

Belette said...

VB: thanks. However, that doesn't tell me what Rahmstorf is supposed to have got wrong about the science. What was it? (mail me if that is more convenient).

Vinny Burgoo said...

Belette, has anyone said that Rahmstorf got anything wrong about the science? He's supposed to have blogged something unacceptably nasty about someone he thought had got the science wrong. Thinking that wrong science is right and getting shouty about it isn't always quite the same as getting science wrong.

But who knows what happened? Or if anything noteworthy happened at all? Rahmstorf's original blog-post has disappeared and a February court-case wasn't reported anywhere until November.

Anonymous said...

Of course, Rahmstorf and the alarmist real-climate-party are right, always, for ever, and the german court is just a bunch of dirty lying climate deniers, who have nothing on their mind than killing Bambies and Knuts (incredibly cute polar bears). I think they work for the tobacco industrie and earn at least 99% of Exxxxon Mobile (the antichrist, a brother of Monsanto).

Have I got this right? Sure! This is "climate science", not "Science".

;-)

Yeph

Anonymous said...

@ghost

Poor Mr Rahmstorf:

Some time ago he posted on his blog:

"Erderwärmung beschleunigt sich"
von Stefan Rahmstorf, 24. Oktober 2008, 22:00
(global warming accelerates)

It is a guest post with Phil Jones. And the same man complains about the media exaggerating his statements.

And he never never ever exaggerates other peoples (skeptik) statements?!

This is hypocrisy at its best. Surely your joking Mr Feynman.

People like Mr Rahmstorf defend everything that supports their cause and pretend to be surprised when people expose and criticize this mess.

People like Stefan Rahmstorf and, much worse, Mr Hoffmann, are the reason (often the only one) why many people become activist skeptchicks.

They are gatekeepers, they are a "Kartell", they "lie" and the german court says exactly this about Rahmstorfs words : "unwahr". That means "not true".

Yeph

Belette said...

VB: I'm not sure, I was hoping that WK might know. But he is keeping quiet. I get the impression that he is more interested in the conflict than any substance.

Neven said...
This comment has been removed by a blog administrator.
Neven said...
This comment has been removed by a blog administrator.
Hans von Storch said...

Neven,
ich denke, Ihre Aussage "Do we know why Meichsner so uncritically copied from Leake who copied from North?" entspricht der Aussage, die das Landgericht als unwahre Tatsachenbehauptung charakterisiert hat. Sie sollten das Urteil lesen:
"Der Beklagte wird verurteilt ... zu unterlassen, den Eindruck zu erwecken, ... die Klägerin habe von ... North und ... Leake abgeschrieben". Sie wiederholen hier also eine gerichtlich festgestellte falsche Tatsachenbehauptung, die unzulässig in die Persönlichkeitsrechte der Journalistin eingreift. Sie tun das zudem unter Nutzung eines Alias-Namens.

Auch ein Blog unterliegt dem Presserecht, und wenn Leser Kommentare einstellen, die dem Presserecht (hier: Verletzung von Persönlichkeitsrechten) widersprechen, haften die Betreiber des Blogs.

Ich lösche daher Ihren Eintrag als verantwortungslos und nachgewiesenermaßen falsch. Ich fordere Sie des weiteren auf, derartige Fehlleistungen zukünftig zu vermeiden.

Hans von Storch said...

Neven, I am also deleting your second comment - it is not consistent with the netiquette of this blog to characterize people as "liars/disinformers".

It may be that you are mainly interested in making certain assertions without a debate and without considering the possibility that your opponents may actually sometimes be right. If this is so, you should refer to other blogs, who are mostly serving the convinced.

Hans von Storch said...

Yeph,
you are not right: saying something "untrue" does not mean that the person is "lying". There is the possibility of an honest error. or lack of insight.

Also I would certainly not share your opinion on Georg Hoffmann, whom I find an interesting partner to discuss with, with lots of competence and knowledge. Georg and me do not always arrive at the same conclusion, admittedly, but I value him highly.

Anonymous said...

Sehr geehrter Herr von Storch (Re#12)

so ganz falsch ist die von ihnen zitierte Passage auch wieder nicht, das Urteil ist da differenzierter.

Das Gericht stellt im Urteil selbst fest, dass sich zwischenzeitlich die Vorwürfe von North und Leake als teilweise falsch erwiesen hätten. Ferner wird bestätigt, dass es rechtens war der Autorin vorzuwerfen, sie hätte die zugrundeliegenden Abschnitte des AR4 nicht gelesen.

Das Gericht verurteilte aber den Gebrauch von "abgeschrieben" in dem Sinne, sie hätte von North und Leake übernommen ohne sich eigene Gedanken zu machen.

Ich kann hier also auf Basis des Urteils feststellen, dass keine Einwände bestehen können, der Autorin vorzuwerfen, ihr Artikel war schlecht recherchiert, worauf Neven wohl hinauswollte.

Übersehen hat Neven, dass es darum überhaupt nicht ging. Es ging darum, dass Rahmstorf bei seiner berechtigten Krtik übers Ziel hinausgeschossen ist und Persönlichkeitsrechte verletzt hat. Das ist der Streitpunkt und daher begrüße ich das Urteil. Pressefreiheit bedeutet meiner Meinung nach, dass auch die Freiheit besteht, schlechte Artikel zu schreiben, ohne in seinen Persönlichkeitsrechten verletzt zu werden.

Andreas

Anonymous said...

I find it of interest to note that Professor von Storch has deleted a comment from Neven because it accused people of lying/misinforming, without allowing us to see the comment, while he responds to another commenter (Yeph) who calls specific people liars and misinformers, but does not remove THAT post.

Duly noted.

Bam

Werner Krauss said...

@Belette #1

As far as I understand, your reading of the case is correct.

@Belette #9

this is correct, too - I am more interested in the case as a symptom. What do we learn about knowledge production in our society from cases like this one? Professors, free lancers, 'independent' media, blogs, the law gather round a dispute about climate: it is really tempting to shift the focus for a moment on knowledge production as a social activity. Climate has turned into a market place for attention and into a battlefield for those driven by the desire to control public opinion (or to gain attention, make a living, a career etc). Weapons in this battle are gossip, character assassination and rumors on the one hand, and apocalyptic visions, conspiracy theories and 'poisoned' knowledge on the other. This creates a permanent state of emergency, and the current case is an expression of this state.
Too far fetched, my interpretation?

Neven said...

Ich lösche daher Ihren Eintrag als verantwortungslos und nachgewiesenermaßen falsch. Ich fordere Sie des weiteren auf, derartige Fehlleistungen zukünftig zu vermeiden.

Verzeihen Sie bitte, Herr Professor. Ich habe nicht gemeint die Fr. Meichsner hatte wortwörtlich alles vom Leake kopiert. Ich habe nur gemeint dass sie sich vom Leake/North irreführen lassen hat und so 'mitgeholfen' hat beim Elephant aus einer Mücke machen.

Vielleicht sind Sie nicht bekannt mit der Arbeitsmethode Leake/North/CFACT (daher den Link zu Deltoid). Ich basiere mich nicht auf einen einzelnen Fall, sondern auf eine systematische Zweifelstrategie. Aber gut, ich werde hier ab heuer andere Umschreibungen für solche Leute benutzen.

Ich kann hier also auf Basis des Urteils feststellen, dass keine Einwände bestehen können, der Autorin vorzuwerfen, ihr Artikel war schlecht recherchiert, worauf Neven wohl hinauswollte.

Genau, darauf wollte ich hinaus.

Übersehen hat Neven, dass es darum überhaupt nicht ging. Es ging darum, dass Rahmstorf bei seiner berechtigten Krtik übers Ziel hinausgeschossen ist und Persönlichkeitsrechte verletzt hat.

Es stimmt auch dass ich das übersehen habe (Danke für die Erklärung, Andreas, vielleicht solltest du in meinem Namen schreiben ;-)).

Kurz zusammengefasst stört es mich bloß dass Leute wie North und Leake einfach weiter machen können was die wollen, und weltweit naiven JournalistInnen bei ihre ideologische Guerrilla (Mücke --> Elephant) einbeziehen dürfen. Und wenn man dann die JournalistInnen anspricht, wird daraus wieder einen neuen 'Skandal' der von Australien bis Amerika als einen Triumph gefeiert wird.

Wenn es sich nur um Forschung nach Kamelenembryos handeln wurde, hätte ich keinen Problem damit. Aber AGW ist meiner Meinung nach eine seriöse Sache. Die Hysterie über die Fehler im AR4 ist genau so irrelevant wie dieser Prozess, vor allem wenn sich erweist dass AGW tatsächlich ein großes Problem ist.

Wann werden bestimmte 'Skeptiker' die offensichtlich auf unsaubere Weise versuchen die Wahrnehmung zu trüben nicht mehr als Quelle aufgeführt?

Oder anders gefragt: hat die Frau Meichsner je zugestanden dass Sie sich vielleicht nicht so leicht von North und Leake aufputschen lassen sollen hätte? Rahmstorf hatte sich weniger aggressiv ausdrücken können, aber völlig Unrecht hat er nicht.

Belette said...

WK, #17: I disagree with your interpretations, but I agree it is reasonable for you to be interested in that perspective.

EliRabett said...

Perhaps someone could explain to Eli the substantive difference between 75 and 250 million and 90 and 220 million people? Perhaps not.

Vinny Burgoo said...

Eli, the substantive difference is that one of them is an error. (I can't remember what the error was or even if I ever understood it, but KNMI said that Arnell acknowledged it.) If you're going to keep presenting a single paper's estimate as What The Science Says almost a decade after it was published, at least get the numbers right.

Arnell gave an almost convincing reason for not correcting the range.

"I think the way in which it was projected with a wide range encapsulated the huge uncertainties, and we think that [narrowing it to] 90-220 million is an over-interpretation of the information that the chapter authors had at the time." (BBC)

(Incidentally, that indicates that the error wasn't Arnell's. Sorry, prof.)

Superficially convincing. But then you start to wonder what he means by 'over-interpretation' (you can't interpret what isn't there) and whether accidental utility is a valid excuse for an error and whether Arnell really believes that exaggeration is an appropriate way of representing uncertainty in a scientific report. (I can't find it at the moment but the first draft of AR4 had the range going up to something like 350 million. An early attempt at quantifying uncertainty?) In the end, you conclude that what he said had more to do with loyalty than science.

Do you have any thoughts, Eli, on the gross/net thing? That, not the faulty maths, is the main problem with the '75 to 250 million'. Most people probably assume that it's net (more water-stress minus less water-stress). I know I did when I first read it. I've yet to find anyone explicitly presenting it as a net estimate but then neither have I found anyone explaining that it isn't, and you have to wonder whether some of those who trot out the numbers out are being ... economic with the actualité.

Rob Dekker said...

In this "debate" between scientists and journalists, Condoleezza Rice's statement comes to mind :

they have to be right once, we have to be right 100 percent of the time.

In the thousands of pages of documents that the IPCC AR4 produced, some journalist will find some error or questionable statement, and calls it a "scandal", and if there is even one other example of a previously documented minor mistake (even if it was admitted and corrected) that journalist will attack the president of the IPCC of "glaring errors of his organization" and even though allegations against Pachauri have been refuted by KPMG, that journalist will still continue to claim that this scandal is "in a different league altogether" because this time Pachauri was "personally involved".

So, what did we learn from all this ?

Well, first of all, that journalists can vent any opinion they want, without context or reason, nor evidence. All they need is one questionable sentence in the IPCC's report that can be taken out of context, and they can crank out an inflammatory story. When they then attach a -gate suffix it will add a sense of mystery to the story, which surely would win over more people who don't like the message the IPCC presents.

Second, Condoleezza Rice is right : scientists DO need to be right 100% of the time. That includes anything the IPCC writes. Which means that every word, sentence and paragraph the IPCC publishes (not to mention anything that a scientist writes) must be checked and double-checked for accuracy, ambiguity and have a peer-reviewed scientific basis.

Third, when attempting to set the record straight on facts, scientists should pick their battles wisely. Rahmstorf made the mistake of attacking a story that cherry-picked the IPCC report, without checking the exact details of the core claims made, and he did it in an authoritarian way. That backfired badly for him. As I learned the hard way : only confront a cherry-picker on the details they have verifiably wrong. Otherwise, don't respond.

Finally, for all of us humans : are we focusing on trees so much that we forgot the forest ?

For example Arnell 2004 (referenced by Rahmstorf) estimated that "by the 2050s between 670 and 1500 million people living in water-stressed watersheds would see a significant reduction in water availability due to climate change". That finding was NOT disputed by Meichsner. So either she does not care about a billion people seeing significant reduction in water availability due to climate change,

If a journalists uses ad hominems and spinned stories that at the core only disputes one statement in a the IPCC's writing, should we really call into doubt the remaining 99.99 % which they were unable to dispute ? And if not, then why do we give so much attention to such public "informers" of the state of climate science and the IPCC summary reports ?

Vinny Burgoo said...

RD: 'That finding was NOT disputed by Meichsner.'

It probably should have been, though. I'm fairly sure that the 670 to 1500 million range is for those experiencing increased water stress because of both population growth and climate change (and population growth is the larger factor). I know Arnell said otherwise in a subsequent paper (your quote is from a 2008 Arnell paper, not Arnell 2004) and that he's brighter than I am and knows a thousand times more about the subject than I do, but there's no indication anywhere in Arnell 2004 that the numbers refer only to the effects of climate change - indeed the paper mentions that range as an example of the 'clear effect' of different population assumptions.

So thanks. You might have 'cherry-picked' another error. (I don't really understand why error-spotting is cherry-picking. It's more like bad-appling.)

There's also the bad-effects-only problem again. The paper says that far more people will experience decreased water stress. There are sometimes sensible reasons why bad impacts are more important than good impacts and for keeping them separate rather than doing a simple sum, but the good should be mentioned along with the bad, and it seldom is. (Ever?)

Rob Dekker said...

I'm fairly sure that the 670 to 1500 million range is for those experiencing increased water stress because of both population growth and climate change

I'm think you are mistaken on this. Arnell 2004 clearly states that in absense of climate change, the number of people in increased water stress areas increases drastically (to 3.4 billion under A1/A2 growth and to 5.6 billion in A2 growth scenarios). So that's the direct effect of population increase.
So I'm fairly the 670 to 1500 million numbers (and also the regional numbers presented by the IPCC) from his model simulation are the direct influence of projected climate changes.

Maybe Arnell could have this (nature of his numbers) more explicit, but I would not call that an "error", let alone a cherry-picked one as you suggest.

Second, There's also the bad-effects-only problem again. The paper says that far more people will experience decreased water stress.

Yes, and it also discusses that effect. Arnell writes :
However, using the per capita water availability indicator, climate change would appear to reduce global water stress. This is because increases in runoff are heavily concentrated in the most populous parts of the world, mainly in East and South-East Asia, and mainly occur during high flow seasons (Arnell, 2004b). Therefore, they may not alleviate dry season problems if the extra water is not stored and would not ease water stress in other regions of the world.

So getting more water from climate change may be a mixed blessing, especially for areas like Bangladesh which gets all that water in one short monsoon season, and have no way to store that water. Are you arguing that they should be happy because climate change will give them more water during the flood season ?

Typically any climate change will require societies to make changes, sometimes costly ones. So I think Arnell was rather conservative in mentioning only the number of people that obtain LESS water in already water stressed areas (which is almost certainly 'bad'), and not attempting to put a value assessment (good/bad) on the areas that will experience an increase in runoff.

Vinny Burgoo said...

RD, what Arnell did in one part of the paper has no bearing on what he did in another part. I'm almost certain now that Tables 10, 11 and 12 were for the combined effects of climate change and population. Arnell discussed them in the paper as though they were and, here and there (see below), others do likewise. Attributing the tables' results solely to climate change probably started as a sort of shorthand. Unfortunately, in some places this shorthand became the full version.

Some examples of Arnell 2004 misattribution in AR4.

1: The 75-250 (88-217) million range for Africa in 2020 (2025) discussed above was said to be due to climate change alone in several places in AR4 (and, incidentally, was flagged with 'High confidence' asterisks in the WG2 SPM). If pop. growth is also implicated, a CC-only attribution for a continent with such a rapidly growing population would be the worst error associated with that particular claim.

2: WG2's Table 20.4 shows 'Global-scale impacts of climate change by 2080', including 'Millions of people exposed to increased water resources stress (Arnell, 2004)'. The numbers - 1-3 billion - are from Table 10. (2085, not 'by 2080'.)

3: WG2 Chapter 13's executive summary said that 'By the 2020s, the net increase in the number of people [in Latin America] experiencing water stress due to climate change is likely to be between 7 and 77 million (medium confidence).' That should have been something like '... net number of people experiencing increased water stress due to climate change [and population growth]'. The mistake arose because a misconceived table was mislabelled. The revised labels also attributed the net increases to climate change alone. Table 13.6. See the Dutch gov.'s report and the WG2 Errata. (Note that these numbers were derived using the same 'inappropriate' method that produced the African 75-250 million estimate. Note also that someone somewhere once thought net estimates were useful.)

The WG2 Technical Summary echoes the doubly wrong statement in #3 but, in another passage, hints at the truth:

'By the 2020s between 7 million and 77 million people are likely to suffer from a lack of adequate water supplies, while for the second half of the century the potential water availability reduction and the increasing demand, from an increasing regional population, would increase these figures to between 60 and 150 million.'

Still wrong but getting closer. Both ranges are from Tables 11 and 12 in Arnell 2004, so they're estimates of those whose water stress will increase, not of how many will be stressed, but at least population growth gets a look-in.

As for keeping quiet about the decreased-water-stress numbers because they might not be wholly good news: no. The study was what it was. It produced 'hugely uncertain' estimates based on a particular definition of water stress. That definition's inadequacies - not restricted to the 'good' side - were covered in the small print. If you don't have the space to paraphrase the small print, don't use the study at all. (And certainly don't mark its numbers with 'High confidence'.)

Rob Dekker said...

Vinny said : I'm almost certain now that Tables 10, 11 and 12 were for the combined effects of climate change and population

I appreciate your attention to detail, but I am now convinced that you are wrong on that, and that these tables address climate change alone.

For starters, table 10, 11 and 12 are refered directly under section "Effects of Climate Change", subsection "Using average annual runoff as the indicator of resource availability". That is already a strong indication that they refer to climate change alone, not population growth.

Even better, the number of people under increased water stress due to population growth alone are actually presented clearly in table 7 :

Table 7 gives you the number of people living in living in water-stressed watersheds by region, in the absence of climate change.

To top it off, table 8 gives you the number of people (millions) in water stress classes, with climate change.
Note that these numbers are much higher than the ones in Table 10, 11 and 12. That is because Table 10, 11 and 12 deal with the effects of climate change alone (not population increase).

Also, regarding the IPCC statement :

'By the 2020s between 7 million and 77 million people are likely to suffer from a lack of adequate water supplies, while for the second half of the century the potential water availability reduction and the increasing demand, from an increasing regional population, would increase these figures to between 60 and 150 million.'

you mention :

Both ranges are from Tables 11 and 12 in Arnell 2004, so they're estimates of those whose water stress will increase, not of how many will be stressed, but at least population growth gets a look-in.

Now let's look at that for a moment. For one, table 11 lists the "increase" in water stress and table 12 lists the "decrease" in water stress. So I'm not sure why you claim that these ranges only pertain to "those whose water stress will increase". That seems either a one-sided biased view, or an accidental misquote. Please tell me it's the latter..

Regardless of that answer, the first range is 7 - 77 million and the second is 60 and 150 million. Now I don't really see these numbers directly in anywhere in table 11 nor in table 12, so maybe you can point out where you think you got them from.

This is what I think : the 7-77 range pertains to the "lower bound" (A1/A2 population growth scenario) by the 2020's and the 60-250 range pertains to the "upper bound" (B2 population growth scenation) by the second half of the century. The IPCC simply wanted to summarize the lower-to-upper bound of two dimensions in one sentence.
So the IPCC was correct to include the notion that "inceased regional population", even though BOTH ranges pertain to increased stress due to climate change.

So I'm not realy sure how much more evidence you need. In fact. if you are correct and Arnell's range numbers quoted by the IPCC should include "population change" then there are at least a dozen places in the IPCC report that contain errors, or simply don't make sense at all. If you are incorrect, and these ranges really pertain to effects of climate change alone, then there is not a single place with an error. So what do you think is the truth ?

Hans von Storch said...

Would it not be wise if someone asks Arnell for clarification?

Rob Dekker said...

That would make sense Hans, and I would be happy to send an email to Arnell. Still, I'm not sure which questions would be the most effective ones to ask, especially regarding the topic of this thread (Rahmstorf versus Meichsner).

Was the issue of 'population-growth-or-not' in Arnell's numbers really a determining factor in Rahmstorf vs Meichner, or not ?

And if not, what WAS the determining factor in this case ?

Hans von Storch said...

Rob, I thought of just the questions related to the tables - what do they show - where is climate change included and where not? I would appreciate if we ("we" :-)) are able to sort out at least some technical questions, even if we must live with the fact that in many cases no agreement is within reach between the different views held by the Klimazwiebel-readers.

Vinny Burgoo said...

I have e-mailed Professor Arnell.

Vinny Burgoo said...

Rob, 'those whose water stress will increase' was my own shorthand: increase/decrease.

Tables 7 and 8 deal with a different phenomenon: the number of people living in water stressed watersheds, not the number of people experiencing increases/decreases in water stress.

To get 7-77 million and 60-150 million, you first add the Meso-America and South America rows for 2025 and 2055 for the four HadCM3 columns in Tables 11 and 12. Find the lowest and highest numbers for each year in both tables. (E.g. 12-81 million, both from the HadCM3 B2 column, for 2025 in Table 11.) Then subtract the Table 12 ranges from the Table 11 ranges.

'... or simply don't make sense at all.'

Indeed. In a few places, AR4 speculates on what would happen to the numbers if population growth (increased demand) were added to the mix.

Vinny Burgoo said...

I misdescribed the method of getting the highest/lowest ranges from the tables. Do everything for each HadCM3 column first and only after you've subtracted the resulting 16 numbers/mini-ranges on Table 12 from those of Table 11 do you look for the highest and lowest for 2025 and 2055. Clear as mud, eh?

EliRabett said...

FWIW, the mathematical part of the "error" in Arnell (see 21: between 75 and 250 million and 90 and 220 million ) is obviously the confidence limits can be interpreted as being narrower under the assumptions of the calculation.

For this you are whacking him?