It seems quite remarkable that the IPCC has released a statement in response to the Daily Mail article on a supposed smear campaign against Richard Tol. It seems to make clear that there may well be errors in some of Richard Tol’s papers, that these errors have potentially made it into the IPCC documents and that an erratum can’t be issued until the journals in which Richard Tol’s papers were published have issued corrections.
There has been a fairly robust exchange about this between Bob Ward and Richard Tol, and it seems hard to argue that Bob Ward wasn’t mostly right (although that doesn’t appear to be stopping Richard from suggesting that he isn’t). I was certainly aware of an error in one of Richard’s papers 6 months ago and Bob Ward started discussing these errors with Richard at about the same time. I will say that I imagine that Richard finds David Rose’s defense of him rather annoying. I haven’t hidden my dislike for Richard’s style of engagement. It’s, in my opinion, robust to the point of being remarkably rude. However, in his defense, he’s always seemed more than willing to take it as well as dish it out. For a journalist to write an article that makes a world-leading economist seem both whiny and hypocritical, must be remarkably irritating.
What’s maybe more interesting to consider is what would have happened had this been papers by Michael Mann, or another high-profile, non-dissenting climate scientist. It’s hard to imagine that there wouldn’t be howls of indignation from the usual suspects (David Rose probably being one of them), followed by accusations of “fraud”, “deception”, and other forms of willful wrong-doing. I guess we can’t know for certain, but given the ongoing law-suit between Michael Mann and Mark Steyn, it wouldn’t seem unreasonable to assume that it wouldn’t be pretty or pleasant. You might think that this implies some kind of double-standard, but one should bear in mind that this is allowed within the rules of ClimateballTM.
As I understand it, the errors in Richard’s papers aren’t particularly significant (and here I’m using significant as it might be understood in general conversation, rather than in some statistically, well-defined way). It’s not going to change things greatly. It’s just about correcting known errors. In fact, it’s quite remarkable that this wasn’t resolved in a matter of minutes with a polite “Thanks, I’ll get those corrected” (actually, no it’s not really remarkable, but you know what I mean).
The Daily Mail article that suggests that there is a smear campaign against Richard Tol also has a short section by Ben Pile which starts with the IPPC report was ramped up to predict wars, extreme weather and famine… while its authors slept on the job. The IPCC statement comments on this to say
The Mail on Sunday article also misrepresents the process by which the Summary for Policymakers of the Working Group II report was approved, and provides incorrect references in the underlying report to excerpts it quotes from the Summary for Policymakers.
If this was at all surprising, I might say more. Since it isn’t, I won’t.
...and Then There's Physics 
Given this apparent direct quote from Richard in the Mail article:
I’m not so sure about this. That certainly seems quite whiny to me, but maybe there is context missing from his quote.
OPatrick,
Yes, that was kind of my point. I have, in the past, credited Richard with at least being willing to take it as well as dish it out. This article makes it appear that I may have been a little too generous in that regard. As you say, though, there may well be some context missing.
Also, is it just me or is the IPCC statement pleasingly deadpan in it’s response to the Tol part of the Mail article? It ignores all the puff and focuses on the substantive point, that there are apparently errors in Richard Tol’s work. Somehow I don’t think this is what David Rose thought he was writing about.
OPatrick,
Yes, it was quite focussed. Maybe the IPCC is learning how to score points in ClimateballTM 🙂
@OPatrick
Errors were found and have been corrected. Conclusions haven’t changed.
Richard,
Really? That doesn’t quite seem consistent with the IPCC statement. They seem to be suggesting that there are still errors that are to be formally corrected. Are they wrong about this?
@Wotts
I don’t know where the IPCC got this “information”. It is incorrect. Errata have long been submitted, error corrections are not contingent on these errata, and corrections were made in trickleback (the IPCC process through which chapters are reconciled with the summary).
Richard,
Wow, so Bob Ward is wrong and the IPCC is wrong?
If a typo on glaciers can discredit an entire UN report I imagine errors in papers can sink a career. That’d be my conclusion.
Climateball is a long game and is played for politics, not science.
The IPCC are not playing climateball, they’re doing (reviewing to be precise) science; they are mere spectators, although as such they can affect the game.
The GWPF *are* playing climateball and their strategy is simple and highly effective: to ensure an appearance of debate on the facts to discredit the science and avoid mitigation.
Rose is the mouthpiece of the GWPF and Tol is employed by them on their advisory board.
All that will stick from this episode is a memory of controversy and debate, not what that controversy was. The GWPF wins, *regardless* of what errata are or are not issued by Tol, journals or the IPCC, and who is scientifically found to be right or wrong.
Tol also sells more books.
Richard Tol
Quick, did you notice what ATTP wrote?
Time to tweet!
VTG,
Indeed, I was just being sarcastic 🙂
I think that the rest of your comment hits the nail on the head. As I was trying to imply in the post, if there were errors in a paper by Michael Mann, all hell would break lose. Errors in a paper by Richard Tol, and it’s a smear campaign. Tails you win, heads you lose.
Yes, if only Michael Mann had thought to say
we could have avoided 15 years of tiresome pedantry.
@Wotts
They issued a forecast: There will be an erratum to IPCC WG2 AR5 Chapter 10 on the numbers in Table 10.B.1.
That is a very specific forecast, so let’s revisit this space in a year or so.
Richard,
Okay, but the statement does appear to relate directly to the Mail article, and the Mail article does appear to relate to your exchange with Bob Ward, so it’s hard to see how the IPCC statement is completely unrelated to Bob Ward’s suggestion that there are errors in your paper/papers.
To be honest, I’m still surprised that this has had as much exposure as it has (the irony of me saying this after writing a post about it is acknowledged). The errors don’t seem that severe. The basic result is unlikely to change. Yet, here we have articles in the Mail and the IPCC releasing a statement. Quite remarkable really, when this could/should all have been over in a matter of a few minutes. And one wonders why people get cynical about all of this.
What is wonderfully amusing is that Tol made great mileage out of the typos in the last IPCC report. Another biter bit.
toby52,
Yes, by and large, I have found this somewhat more amusing than maybe I should have 🙂
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@Wotts
I agreed that there is a lot ado about almost nothing.
I had a debate with Bob Ward on Channel 4 last Monday. He convinced them to do a re-match on Wednesday. That’s where this story got legs.
Richard,
Hmmm, yes, but if you think I’m implying that Bob Ward has gone overboard, you’d be wrong.
Yes, until then virtually no-one had heard of you or your contributions to the IPCC as there was too much focus on the key messages contained in the report.
Could RT explain why he considered the Stern report, which has been used in the peer-reviewed science, to be grey literature, and why he seems to have relied instead on Tol et al, 2015?
Given earlier admitted errors in previous papers from RT, I would have thought that Tol et al, 2015 was currently a very murky shade of grey.
@idunno
We did not ignore Stern. We used Hope (2006) instead, because that allows us to compare like with like. (If we do that, IPCC is actually more pessimistic than Stern.)
We did not rely on Tol et al. 2015 (Tol 2014 more like). I wish we could because that answers questions about significance and outliers.
I don’t think we can read too much into the part of the IPCC statement which deals with Richard Tol’s “errors”. It says it *understands* that Tol intends to issue errata on some of his papers and that *if* this happens it will update its reports accordingly but it doesn’t actually come out and say that there actually were (or were not) errors in his report.
I do find the following statement interesting though and wonder if Richard could confirm whether it is correct
Professor Tol withdrew in September 2013 from the core writing team that produced the Summary for Policymakers. However he participated actively in the approval process for the Summary in March 2014 and agrees with the final wording on all statements related to the chapter on which he worked.
Of course the IPCC statement is pretty damning on David Rose’s journalism, which is hardly a surprise. It still wouldn’t surprise me if the “green smear campaign” was all Rose’s idea, it certainly fits with his previous form. I know the quote mentioned by OPatrick would appear to contradict that, but Rose does have a long history of twisting or outright inventing scientists’ views to fit his desired narrative.
Mind you, when I wrote that comment I was forgetting Richard’s involvement with the GWPF. Given the way that Rose acts as a mouthpiece for the GWPF it’s a bit harder to to believe his piece didn’t have Richard’s approval.
No, the story got legs when Tol blathered to the media at the outset.
Missed one…
Mann is also suing Tim Ball;
For a truly hilarious time, read this article about Tim Ball’s ‘lawyer’;
http://www.desmogblog.com/affidavits-michael-mann-libel-suit-reveal-astonishing-facts-about-tim-ball-associate-john-o-sullivan
And of course Tim Ball himself;
http://www.desmogblog.com/timothy-f-ball-tim-ball
In the case he dropped in Alberta, the Calgary Herald dismissed Ball’s credibility saying that, “The Plantiff (Dr. Ball) is viewed as a paid promoter of the agenda of the oil and gas industry rather than as a practicing scientist.”
Jsam, you keep alluding to a typo that was used to discredit the last WGII report. The 2035 thing was much more than a typo. It might have been a typo originally but it was repeated for five or six years before it finally appeared in AR4 WGII (and IIRC some of the repetitions were by the bloke who initially claimed it had been a typo: Hasnain?)
The IPCC reports are about the world’s experts coming together to distill the (nearly) current scientific wisdom on climate change. When a long-established howler like that gets through, of course it discredits the entire process. And so it should.
Happily, WGII seems to have taken absorbed this lesson. The new report seems much less forgiving of wild and wacky claims. (Apart from the stuff about indigenous/traditional knowledge.)
Vinny,
I think this depends on what you mean. If you mean that it discredits/invalidates everything else, then what you’ve said is – in my opinion – complete and utter nonsense.
“What’s maybe more interesting to consider is what would have happened had this been papers by Michael Mann, or another high-profile, non-dissenting climate scientist.”
Cuts both ways. When Andrew Montford is up against a climate scientist on the TV or Radio, that’s false balance. But when we have Bob Ward vs Richard Tol then “it seems hard to argue that Bob Ward wasn’t mostly right”.
Not only that but at least AM doesn’t pass himself off as having relevant expertise. However Ward has been presented as a ‘scientist’ and ‘expert’ when as far as I can tell he is neither (‘IPCC expert reviewer’ doesn’t count). If the grade inflation continues at the present rate we can possibly look forward to Mr Ward giving the Royal Institution Christmas Lectures by the end of the year. Maybe then the LSE will have to find one of the actual qualified economists they presumably have about the place to make the case, instead of just making it look like one of them is?
So indeed it does seem that there are obvious parallels with some plucky ‘blog scientist’ raising errors (that apparently make no difference) in the work of an expert, and spinning in order to distract from the actual conclusions reached by that expert.
I look forward to Vinny actually reading and digesting the IPCC report.
Those denialists who live by blogscience die by blogscience.
Frank,
But I wasn’t arguing that it was right for Bob Ward and Richard Tol to appear against each other on the news. I was simply suggesting that Bob Ward appears to have highlighted errors in Richard Tol’s work. There’s nothing in the post about their appearances in the media.
I disagree that the spinning’s come from Bob Ward. Richard could have simply acknowledged the errors and moved on. It wouldn’t have been difficult to do. I do think that comparing Bob Ward to a “plucky blog scientist” is not entirely fair. He does have a formal position in an institute that focuses on climate change. If this is going degenerate into a “has PhD” versus “doesn’t have PhD” then it’s going to get a little pathetic.
jsam, you mean the latest WGII *is* full of wild and wacky claims? Oooh noooz!
You have spoiled it for me.
I’ll still finish it, anyway, but shame on you.
Shame on you, Vinny. Your conspiracy theory is showing.
“I was simply suggesting that Bob Ward appears to have highlighted errors in Richard Tol’s work.”
Well I am suggesting that Richard Tol also appears to have highlighted errors in Bob Ward’s work, and also appears more likely to know what he is talking about.
“I disagree that the spinning’s come from Bob Ward.”
It’s clear that his presentation (e.g. posting on the LSE site, allowing himself to be presented as an ‘expert’, allowing inconsequential errors to be presented as materially undermining conclusions) is all about credibility – shoring up his own, and attempting to undermine Tol’s. That’s the very definition of spin and as a PR guy it is pretty much his job description.
Who says the errors are inconsequential?
If you mention B** P**** too often he comes and starts commenting. You don’t want that, trust me.
Frank,
Well, I certainly can’t claim that everything Bob has said is correct, but Richard’s response is – in my opinion – the epitome of pedantry. You’ve missed the lengthy discussion on an earlier post about the meaning of the word “significant”.
To be honest, I’m at a loss as to how to respond to this. You really believe this? It’s all about undermining Richard Tol. There are errors in his papers. They may not be that consequential, but they would be easy to fix and easy to acknowledge. Instead, we’re having this discussion about whether or not the person who highlighted them was playing a PR game. As I said in the post, imagine if it was Michael Mann. We’d have people pontificating about scientific integrity and honesty. ClimateballTM is alive and well.
Frank,
I see your point and I appreciate you pointing out parallels like these. I actually find it comforting because it suggests to me that we are not an echo chamber here and we are also less hypocritical than “Skeptics”. I will slightly disagree with you on this point though and my reasoning is that Bob Ward is the one who found errors in Professor Tol’s work so it seems appropriate that he should be the one to confront him about it.
On a somewhat related point, I find Bob Ward’s issue with this statement in Chapter 10 of the report – “Estimates agree on the size of the impact (small relative to economic growth) but disagree on the sign (Figure 10-1)” – pertinent. It’s referring to this chart I think where all but one of the data points show a negative impact. Wouldn’t it be more correct to say that most estimates agree that the impact will be negative? But I’m neither an economist nor a statistician so I’d be curious to know what other people make of it.
It is mildly amusing to compare and contrast the current episode with Tol v Cook, one example of which is here, http://richardtol.blogspot.co.uk/2013/06/draft-comment-on-97-consensus-paper.html.
Rachel,
I’m not an economist or a statistician either but there’s more to the statement than that:
“Estimates agree on the size of the impact (small relative to economic growth) but disagree on the sign (Figure 10-1). Climate change may be beneficial for moderate climate change but turn negative for greater warming. Impacts worsen for larger warming, and estimates diverge.”
That’s just adding a couple of sentences. But that much makes it clear that how much agreement there is depends what amount of warming you are talking about. When you look at the chart you can also see that there aren’t a lot of estimates at the lower end. Indeed the presence of a flipping picture kind of deflates the argument that this section is somehow misleading. The rest of the section includes even more caveats.
“Wouldn’t it be more correct to say that most estimates agree that the impact will be negative?”
I guess it would be equally correct but if that was all it said then that too would leave out relevant information that Chapter 10 doesn’t.
That said I would rather that the graph showed the uncertainties in some way as some of them don’t exclude 0 (plus given the rough nature of some of the estimates you could even argue for something like this http://www.chrisstucchio.com/blog/2014/why_xkcd_style_graphs_are_important.html).
To be honest given the big uncertainties and the fact that some or all of the estimates leave something out, I am surprised the maths doesn’t blow up. The original paper(s) is/are pretty clear on all those caveats but still. The original is also IMO clear that while these estimates are the best information we have, that still isn’t very good.
I also don’t follow the argument that if the best estimates don’t turn negative until a substantial amount of warming, that means it isn’t dangerous. After all the best estimate for a game of russian roulette is that you probably won’t blow your head off, but most people would consider it dangerous anyway. Driving a car is also dangerous, even though the most likely outcome is beneficial.
(Instead of ‘that means it isn’t dangerous’ above I should have said ‘it’s not well supported that it’s dangerous’, or similar).
Bob Ward works for the Grantham Research Institute on Climate Change and the Environment which is part of the London School of Economics and does research into the economics of climate change. He has published several papers on the subject of climate change impacts and adaptation.
Therefore while I agree with Rachel that we should be careful about double standards I don’t think he is a completely inappropriate person for the BBC to be interviewing in this context.
I must admit from my, limited, perspective the Ward/Tol dispute seems far from clear-cut and probably exaggerated in significance. However, Tol can hardly complain about the attention given that he manufactured attention his way in the first place.
Vinny:
At the risk of a long and tedious period of Climateball other than the Himalayan glacier claim can you give any other genuine examples of ‘wild and wacky’ claims in the previous WGII report?
jsam: THAT IS HILARIOUS!
http://richardtol.blogspot.co.uk/2013/06/draft-comment-on-97-consensus-paper.html
My gosh he quibbles in excessive exhaustive microscopic detail!
I dare not say ‘significant’ because I’m not sure what version of the word he’s using today. But talk about Tol wanting a Double standard… Nah… I’ll go out on a limb, he wants a standard that means what he wants it to mean at this time. That is probably the safest to use in relation to Richard Tol at this moment in time. Lets see what tomorrow brings.
It’s eerily similar to the way Nic Lewis tried to cast doubt on AR5 WG1 on the central issue of sensitivity. Outliers with very loud voices, but still outliers when all the fuss is over. But the public only hears the fuss.
And behind the scenes, the GWPF.
andrew adams
Dimitri Zenghelis is also critical of RT, and apparently credible:
Given that what Dear Richard wrote in the WGII report was more than a little based on the results that were, shall Eli say, a trace off, why yes, this is significant.
ATTP: “As I understand it, the errors in Richard’s papers aren’t particularly significant ”
Perhaps, but…
“Simples. Science is a method, rather than a set of results. If the method is wrong, the result is invalid.” – Richard Tol (https://andthentheresphysics.wordpress.com/2013/07/26/richard-tol-and-the-97-consensus/)
What is truly new here, and in the 538 thing, is that people are standing up to the bullies (Tol and Pielke). Their entire mode of operation has been to go crazy and dare anyone to dig in against them and up till now no one has. The IPCC press release is a remarkable marker.
ATTP: “As I was trying to imply in the post, if there were errors in a paper by Michael Mann, all hell would break lose. Errors in a paper by Richard Tol, and it’s a smear campaign. Tails you win, heads you lose.”
The expression is “Heads I win, tails you lose”.
Layzej: Interesting.
So Richard believes his own work is invalid?
I wonder what definition of ‘invalid’ he was using that day. It can be kind of hard to tell with him. What did Inigo Montoya say? “You keep using that word. I do not think it means what you think it means.”
Layzej,
Yes, I remember that.
Eli,
Indeed, this does seem like something of a turning point.
Magma,
Yes, I did get that the wrong way around 🙂
Bob Ward found two errors, a typesetting one in the Journal of Economic Perspectives and a typographical one in the IPCC report. We thanked him for his scrutiny and corrected them.
There were a few other errors discovered by other people that were corrected too.
None of these errors has a substantial or indeed significant effect on the results.
Ward thinks there are more errors still, but he is simply wrong. We repeatedly explained that to him.
In a normal situation, that would be it. In a highly politicized situation, these things are discussed in public, even on TV. That’s the way it is.
There are two problems with Ward’s behavior. He claims there were more errors than there actually are. Only at this point, his lack of expertise comes into play: The alleged errors reflect his lack of understanding. He also claims that we were reluctant to correct the errors found, even though he knew the errors had been corrected already.
The parallel with Cook is a false one. The errors in the Cook paper do change the qualitative insights. In fact, none of their key results stands up.
Evidence of conspiracy ideation abounds. The noise of economists’ tossedtoys landing on the floor is in equal abundance.
Richard,
Come one, let’s not go into the realms of fantasy here.
Okay, in the interests of civility, I won’t say anything.
Why am I not surprised you think this. I don’t think that the parallel people are suggesting has to do with the significance of the errors.
Richard,
Of course, I’ve worked through quite a lot of your re-analysis of the Cook et al. data and what you’ve done is mostly pedantic nonsense that entirely misses the point of the study. Of course, the key result in Cook et al. is almost certainly roughly correct (i.e., the number of genuinely dissenting papers in the literature is small) and so there would seem to, at least, be some parallels with the current situation.
ATTP
Just thought that was worth repeating before rabbit holes are entered.
Might also be worth adding
which was, of course, the reason why it generated such howls of pedantic protest and squidinkery
Previous Richard felt that it didn’t matter whether or not the errors have “a substantial or indeed significant effect on the results”. He said “The results may be correct, but it is not valid.” and “Validity matters for long-term credibility.”
If I understand correctly Tol’s issues with Cook’s paper were not considered worthy of publication. Even still, by raising questions publicly he was able to undermine Cook’s credibility – my guess is that this was his purpose.
He then comes here and expresses dismay that issues with his paper are being publicly discussed – even after distributing a mocked up picture of Ward with the hairstyle of Irish pop music twins Jedward.
It is all very bizarre.
You’d think he’d be above Jedward comparisons.
[Mod : Okay, I’ll grant your wish 🙂 ]
The countdown to me being moderated starts…now…
@layzej
Validity matters, of course, which is why I correct errors when found.
Richard Tol; I’m reading this;
http://www.lse.ac.uk/GranthamInstitute/Media/Commentary/2013/Oct/lord-ridleys-flawed-article-spectator.aspx
Can you confirm that you are showing positive benefits due to climate change, and that you did this by ignoring the impacts to recreation, tourism, extreme weather, fisheries, construction, transport, energy supply and morbidity?
Even the denial community likes to talk about the medieval warm period, yet that period in history also shows mega droughts in North America, droughts aren’t cheap. People are financially liquidated by droughts; (I don’t claim this is a valid source, just merely an example.)
http://www.utexas.edu/know/2012/09/10/great-texas-drought/
@OilMan
Extreme weather and morbidity were included.
The sign of the impact of climate change on recreation, tourism, construction, transport, and fisheries is unknown.
And the impact on the energy supply? Are you arguing that it’s positive, when higher temperatures reduce PV efficiency and exacerbate droughts that have already shut down some nuclear plants?
DumbSci: By Tol’s language, he’s saying its unquantified.
But its definitely a negative uncertainty. I’d be more concerned about dams running out of water. Regions where that happens will build more coal plants and accelerate Climate Change.
Disaster tourism might increase, so that sign might be unknown. But construction? It’s well documented that worker productivity declines during heat waves, especially those working outside like construction workers. Fisheries? Given the simultaneous threats of ocean acidification and higher temperatures (which lead to anoxia), I’m skeptical that the sign of the impact of climate change on fisheries is unknown.
AnOilMan, “unknown sign” is a stronger claim than “unquantified”. The feedback process you describe has me concerned too.
DumbSci… productivity was zero during the Calgary floods (Alberta’s flood plains are expected to increase 30-50% in size due to climate change). Heck, it was a few days before I could get to work.
Damage to fisheries should be completely known. It is know how migration patterns are changing, it is known what the direct impacts are to harvested fish. (Seriously… government fishery departments watch this one.)
Some fisheries are likely to benefit (read: those from rich countries, while poor countries will lose). This comes from Chapter 6: Ocean Systems:
Forestry in BC Canada is looking at an End Game Scenario due to Pine Beetle Infestation. (Interesting… they removed the 2020 projections. They looked pretty grim.)
http://www.for.gov.bc.ca/hfp/mountain_pine_beetle/
And conversion of forests to Carbon Sources, not sinks.
http://www.unbc.ca/releases/2007/climate-change-and-mountain-pine-beetle
Its also costing jobs. Wow… 53% employment loss.
http://www.cbc.ca/news/canada/british-columbia/confidential-pine-beetle-report-warns-of-economic-and-social-havoc-1.1209969
Thanks Rachel. It’s comforting that “this” refers to the previous sentence: “Animal displacements are projected to lead to high-latitude invasions and high local-extinction rates in the tropics and semi-enclosed seas.”
So fisheries across the southern hemisphere and the tropics could experience a 40-60% drop, and high latitudes could experience a 30-70% increase because of invading species fleeing local extinctions. This might be “positive” in an amoral economic sense because rich people pay more for fish. Yay?
DumbSci: Many conservative (and republican) minded folks really to believe that its OK to harm others as long as they are the one that benefit. Indeed much of our society of predicated on this notion. Its also conveniently hidden with Capitalism. If its not a direct monetary cost, its nothing.
Richard Tol – “The sign of the impact of climate change on recreation, tourism, construction, transport, and fisheries is unknown.
An admission by Tol that his paper is worthless.
DumbSci,
This might be “positive” in an amoral economic sense because rich people pay more for fish. Yay?
It’s terrible, I agree. I personally think the ideas in economics that rich people are worth more than poor people or that the natural world has no value are just wrong and need changing.
Maybe. I grew up in Louisiana and nearly my entire family there and in Alabama identify as conservatives. I disagree with them (out loud extremely rarely and hopefully politely) about a lot of topics, but I don’t think they’re OK with harming others even if they benefit.
In fact, that’s one reason I’m skeptical that an increased catch at our fisheries will actually result in an economic benefit, even in an amoral sense. Namely, America’s not going to just watch the tropics and southern hemisphere starve. To its credit, our foolishly vast military has helped disaster victims for decades, and few (if any) conservatives dispute these goodwill missions despite their costs. These costs make me wonder if America actually would benefit even in an amoral sense because… I hope… we wouldn’t actually be able to stand by and do nothing.
Rachel,
I personally think the ideas in economics that rich people are worth more than poor people or that the natural world has no value are just wrong and need changing.
I agree. Before any economists interject, I do understand that an undistorted life insurance market couldn’t offer an aboriginal subsistence farmer in Somalia the same policy as an American CEO. That doesn’t stop me from dreaming about a world where a person’s value is disconnected from their income.
So… I finally took the time to read it all. (Mainly because Tol hasn’t been too obnoxious, at least to me.)
Bob Ward points out some errors, which appear to be valid.
http://www.lse.ac.uk/GranthamInstitute/Media/Commentary/2014/March/Errors-in-estimates-of-the-aggregate-economic-impacts-of-climate-change.aspx
Largely with Tol, 2002, 2009, and 2013. I read 2009;
http://www.aeaweb.org/articles.php?doi=10.1257/jep.23.2.29
I confirmed the error with respect to Norhaus 2006;
Click to access 3510.full.pdf
All errors are in the direction of ‘less concern’, but how significant they are, I can’t tell. They have now propagated to the IPCC report.
More than anything else I get the impression that Richard Tol has serious problems with manners. This behavior has a distinct correlation with denier behavior, which probably doesn’t endear him much.
curious isn’t it that the errors are all in one direction? if i didn’t know better i’d say that Tol isn’t behaving like the objective economist that he works so hard to portray. oh wait.
Marlowe, yup…
Since some may have missed it, I’ll repeat a key passage from Tol’s 2009 review paper that I quoted in a prior thread:
I think we’re looking at a physical intuition that still hasn’t changed. Several of those unknown unknowns have become more known since 2009, and I suspect they’re not done with us.
AnOilMan, Tol would no doubt disagree that he has made an error with regard to Nordhaus 2006. Crucially, Nordhaus 2006 contains six estimates of the impact of climate change for a 3 C increase in temperature (shown in table 2. These are the output weighted, population weighted and area weighted estimates for the CC1 (temperature change but no precipitation change) and CC2 (temperature and precipitation change) scenarios. In table 10.b.1, the IPCC WG2 reports the output weighted estimates for CC1 and CC2. As the values are compared to Tol’s value for 1 C warming, which is based on output weights (according to Nordhaus 2006), that is the correct comparison.
Having said that, use of output weights assumes economic growth in the OECD nations at least equal to that in third world nations over the coming century, which is dubious. It also discounts costs to poor people relative to wealthy people. Therefore the caveat in the section containing the table should be paid careful attention:
AnOilMan, I would dearly love to pick your brain about some issues relating to a possible 2016 California ballot initiative aimed primarily at stopping exploitation of the Monterey shale. If you’re willing, maybe you could get an anonymous email account for the purpose.
@Tom C
One should compared like with like. All other estimates are output-weighted, so Nordhaus’ output-weighted ones are shown.
Richard Tol, that is exactly what I said at the end of my first paragraph.
Having said that, given the obvious ethical issues with output weighted estimates, I have to wonder why you only gave output weighted estimates in Tol 2002, and why the IPCC did not rework the values where possible and also report population weighted estimates? Had I been a representative of a third world country, I would have rejected chapter 10 simply based on the implicit racism in neither using population weightings, nor even explaining the the estimates of the total impact of climate change where output weighted rather than population weighted, and the significance of that fact. Failing to even discuss the issue was shoddy.
As an aside, you may want to look at and correct the range given for Hope 2006a if you have not already done so.
Well, well, due to a tardy press release I missed this article when it first came out a few days ago, but it seems the climate economics models, Tol’s included, have been weighed in the balance and found to be not much better than a poke in the eye with a sharp stick. It seemed weird throughout this discussion that others working on WGII hadn’t noticed all these problems, but apparently they had.
Can we now look forward to the Beeb featuring this?
Hmm, speaking of media coverage, very likely Tol knew this was on the way, so did he take the opportunity to make his splash first (and simultaneously undercut the impact of the article)?
A quick check of Google News using the first author name finds the Nature article itself but nothing else. That’s sad.
@Tom C
First, many would follow Tom Schelling’s argument (1986, Choice and Consequence) that output-weighted aggregation is appropriate.
Second, equity weighting is not appropriate outside its decision making context (Anthoff et al., 2009).
Third, equity weighting is not uniquely defined (whereas output weighting is).
Fourth, equity weighting is sensitive to resolution. Comparing equity weighted estimates from studies with a different spatial resolution is meaningless.
Richard, from the point of view of a non-expert blog-reader your comment is not helpful. Giving citations to inaccessible papers as your only explanation of gnomic points hints at obfuscation rather than enlightenment. Would it be possible to expand on each of your responses to Tom Curtis? For what it’s worth, my impression of your argument is that equity-weighting is not well defined and is complicated by other factors so it is preferable to use a measure which is well defined and discrete. I’m sure this isn’t really what your argument is.
OPatrick,
As I understand it, that is roughly what Richard’s argument is. I don’t think, however, that it negates the point that Tom was making with respect to poor versus wealthy countries.
Hmm, sounds like equity weighting might be on the agenda:
Using equity weighting in model calculations is in a way a major improvement, but I don’t think that it’s approaching a full solution. Damages (and benefits) vary in innumerable ways. Making them commensurate and deciding what distributional distributional and intergenerational justice mean are far more complex issues.
While some choices may give more just results than others on the valuation, designing solutions that work towards a better-off future is an additional problem. Direct economic competition augmented with Pigovian taxes or other ways to internalize externalities is efficient in solving some problems, but problematic when both poor and rich countries are involved. What seems to be good for the environment and common good, when only rich countries are considered may lead to increasing misery among the poor. The rich may have enough money to buy the resources the poor need to survive.
We should both agree on ways to measure common good on global and intergenerational level and approaches that genuinely help moving towards that common good.
Among environmental and development economists that I have read, I have liked Partha Dasgupta best. He cannot propose ready solutions, but his ways of approaching the problems are in my view more promising than what others have proposed.
What if the discount rate is negative? http://www.sciencedaily.com/releases/2014/04/140408111534.htm
jsam, we cannot contemplate global warming causing negative economic growth (which would justify a negative discount rate). Doing so would threaten our good standing with the GWPF. Therefore it is essential that all integrated assessment models mandate ongoing economic growth regardless of what is happening to the environment /sarc
That’s the press release for the article I linked, jsam, which BTW is not paywalled.
Richard Tol:
1) I did not wonder why you did not give only population weighted estimates. I wondered why you only gave output weighted estimates. Therefore if only “many would follow” Schelling, then presumably also, many would not. That, therefore is no reason for not giving population weighted estimates.
2) My understanding of the purpose of IPCC reports is to guide decision makers. Arguing that population weighted estimates should be excluded from the IPCC reports because they are “not appropriate outside their decision making context” is a non sequitur. (As an aside, which Anthoff et al (2009). I have come across four of them so far.)
3) I did not discuss “equity weighting” but “population weighting”, which is uniquely defined. I would not, however, be adverse to discussing alternative equity weightings and their merits.
4) I don’t see why population weighting would depend on resolution, but allowing that it does – surely it was you job as an IPCC lead author to discuss the relative merits of various weightings, so that policy makers could make informed choices. You seem, instead, however, to have swept a large area of controversy among relevant experts under the carpet lest policy makers make decisions you do not favour.
If you want others to act on the principle that the ethical value of a person is a linear function of their income, you should argue that explicitly rather than by sweeping other principles under the carpet.
Whether negative a discount rate, or a very low discount rate, can be justified at all depends on the intended use of the discount rate. If it’s used in an assessment of a particular investment, I don’t think that very low discount rates, let alone negative ones, can be justified – ever. The reason is that the outcome of the investment must be compared to the case of not doing that investment, and the discount rate determined from the net values of the alternatives. Really stupid decisions would result from not requiring a significantly positive discount rate.
What “significantly positive” means in the above depends naturally on the alternatives.
To avoid misunderstandings, I add that all externalities should be included in my above arguments.
Others feel differently about the discount rate. http://www.law.uchicago.edu/files/files/Fleurbaey%20paper_0.pdf
Tom’s point is salient. Selecting discount rates is a policy decision – transparently show your workings.
Peka, I set up two rudimentary scenarios on a spread sheet to explore this issue. In scenario 1 (investment), it is assumed that no efforts are made to mitigate climate change, with the money saved increasing the growth rate per annum by 1%. The economy grows at a base rate of 3% per annum plus the return on investment until 2030 (ie, 4% per annum with the investment), then shrinks at a base rate 3% per annum due to the effects of climate change (ie, 2% per annum with the investment). In scenario 2, the economy grows at the more restricted rate of 2% per annum due to the costs of mitigation, falling to 1% per annum after 2030 due to the impacts of climate change. Both scenarios start in 2000 and end in 2100.
As expected, the size of the economy grows more rapidly in scenario 1, reaching a peak of 3.24 times the 2000 economy in 2030, but falls there after so that by 2100 it is only 79% of the 2000 economy. IN contrast, scenario 2 grows steadily, reaching a peak in 2100 at 3.6 times the 2000 economy. I think any perspective that does not preferentially weight the current time must prefer scenario 2 to scenario 1. Despite that, discounts rates of 5% and even 3% overwhelmingly prefer the disastrous first scenario. Even a discount rate of 1.8% shows not appreciable preference for the second rather than the first scenario.
This shows that there is no presumption in favour of high discount rates in assessing investments. Your assumption that there is comes from an implicit assumption that there always exists an alternative investment that gives those high returns. That is not a valid assumption when considering climate change.
My scenarios do not show that negative discount rates are desirable. A zero discount rate strongly favours the more sensible scenario 2. However, if we extend the duration of initial growth, and extend the period under consideration the appropriate discount rate could be brought arbitrarily close to zero, and there may be scenarios in which it ought to be negative.
Tom,
I didn’t say that the correct discount rate must be high, only that it cannot be very low.
On the other hand I don’t think that your model can tell anything on the point I tried to make. One part of my claim is that externalities must be included in the calculation. Consuming exhaustible resources of damaging the environment so that future living conditions get worse involves externalities. That would make your high growth case worse than the other cases in properly performed assessment.
But there are also other problems. Most solutions that are introduced now get outdated in future, and often faster than most think. Thus such solutions must have a short enough payback time. There’s an economic risk involved in investments due to this. This risk is exactly the same kind of risk that leads investors to require a risk premium on most investments. Having a risk premium means that the correct discount rate is higher.
The dynamics of economy, both of a growing economy and of a shrinking economy, requires that individual investments compete and that the best are chosen. Return on investment is the measure that tells, which are good enough and which are not.
Getting externalities properly included in the analysis is a real problem, but it’s not helped at all by giving up the idea that return on investment is the proper guide.
@Tom C
Population weighting is an ill-defined approximation of equity weighting.
WG2 does not consider optimal climate policy, so it should not discuss equity weighting.
Anthoff et al = Anthoff, Hepburn, Tol.
Anyone but Tol and Anthoff agree on equity weighting for climate change??
jsam,
I had a look at the paper of Fleurbaey and Zuber. I didn’t read it carefully, but I may do that later, because I’m really interested in the issue.
To me the main reason for much of the controversy is that too much is loaded an a single concept. There’s a rule in economics that a single tool can solve only one problem, but discount rate is used in discussing more than one problem. The operatively most common use is in choosing between investment options. That’s not the same issue as deciding on intergenerational justice. In practice it’s not even the same issue as deciding between consuming and saving during the lifetime on one individual.
Saving may mean either leaving resources unused or investing in something that’s of value in future. It’s not at all obvious that the same discount rate works equally for both. Sterner and Persson have written a paper An Even Sterner Review (the pun is surely intended), which discusses this point. I had once the opportunity to discuss with Thomas Sterner on these ideas. He couldn’t convince me on his quantitative results, but the idea seems to be valid.
Using very low discount rates leads also to the dominance of highly uncertain estimates of costs and benefits. The outcome of the calculation is actually determined almost totally by subjective choices of the analyst on the expected development of the costs and benefits. It’s common to make directly or indirectly assumptions that imply positive or negative growth rates for those quantities. These growth rates may exceed a low discount rate. That might result in diverging net value. That might also lead to nicely converging outcome, when the growth rate of the non-discounted costs and benefits is negative. The latter case gives similar results with a calculation based on higher discount rate and constant costs and benefits.
It’s totally impossible to get quantitatively meaningful net values from a long term calculation of net economic outcome, when neither the discount rate nor the development of estimated costs and benefits makes the calculation converge. This does not mean that the nicely converging result would be the correct one. It means only that the converging case is the only one that can be described by a relatively stable net value.
This dilemma has led me to think that we need a different approach. Calculating the net present value of future alternatives works only, if the outcome is benign. I cannot see any value in the quantitative results of Stern Review, but I accept that the results imply that the non-benign case must be studied in some way that gives meaningful results. This is one reason for my interest in the work of Partha Dasgupta. He seems to have reached similar conclusions and to have spent significant effort in search for an alternative approach. A collection of his papers in that direction can be found in his book Human Well-Being and the Natural Environment. Unfortunately he has not got very far in his search. Some more new ideas are needed to proceed.
Very briefly I interpret the approach of Partha Dasgupta to be based on the idea of Dynamic Programming, where decision alternatives are analyzed looking at
– the costs and benefits over a limited rather short period
– the value of the final state at the end of the period.
The value at the end of the period depends on more distant future. In Dynamic Programming the value is estimated iteratively by repeating similar steps of finite length, but at some point other criteria are used in estimating the relative values of alternative final states. My belief is that it might be more realistic to compare directly the values of alternative states in not very distant future than to perform the full discounted summation in case where it does not converge rapidly.
I add a theorem:
I consider it certain that the quantitative results of all calculations that apply a very low discount rate, and which do not have other effective mechanisms of cutoff are meaningless based on this theorem. The discount rates used by Tol and Nordhaus may be high enough to keep the results meaningful, but being meaningful is not at all a proof of being correct. Those who argue for low discount rates might be right, but they can justify only qualitative conclusions and perhaps some lower limits based on their approach.
@Pekka
Fleurbaey and Zuber are correct.
In applied work, results with a low discount rate are often a function of the time horizon. See the works by Azar and Kandlikar in the early 1990s. We showed that Stern’s choice of discount rate means that he should have put the time horizon in the year 12000 (rather than 2200).
Peeka/Richard,
re low discount rates and climate change. Surely the point is that unless you choose a low discount rate, compounding very rapidly reduces very large future impacts to essentially zero value.
Which is exactly the issue with climate change – the impacts are potentially very large, but a very long way into the future.
My understanding (sorry, can’t recall where I picked this up) is that the use of NPV in decisionmaking in these circumstances should be accompanied by risk assessment rather than being used alone.
Is this valid?
Can either of you point towards a layman’s introduction to the choice of discount rates for high impact events a long way into the future?
An oldie, http://www.ciesin.org/docs/010-291/010-291.html.
VTG,
I can refer to some discussion of Fleurbaeuy and Zuber here. The explain by several arguments why the market rate is not the obvious choice for the discount rate, and why even a negative discount rate could be more appropriate.
My above disagreement goes along the line that searching for the right discount rate may in that case be futile, because people, including competent economists, are not accustomed in comparing such alternatives through a discount rate. People are probably more competent in comparing the physically described alternatives and give their preference on that basis than in estimating the monetary equivalents of the alternatives before discounting. If we cannot evaluate the values to discount, we cannot compare their values after discounting.
I’m for the use of economic analysis as far as it can give reasonably well defined results, but beyond that point some other approach must be taken. Calculations give relevant numbers assuming that the input is not too uncertain, but what can we do with numbers that vary widely depending on choices that cannot be described as anything much better than random subjective choices by the persons who do the analysis.
The dilemmas in using the precautionary principle are huge. We cannot take into account all threats that someone can imagine and that cannot be proven as totally impossible, a limit must be put somewhere. On the other hand the most severe outcomes are weighted strongly, which has the opposite effect. When the likelihood of a risk is very low and estimated only through informal assessments, and when the consequences are potentially very high but equally badly known, calculations cannot tell fully relevant answers. Choosing the discount rate may be a problem, but not the most difficult or the decisive problem.
It’s illustrative to try to imagine decision making 100 years or 150 years ago. How could economists of those times could have done comparisons that compare issues that were not seen as directly important over the first 50 years but more probably around the present time? How much more competent are the present economists in comparing alternatives of the 22nd or later centuries.
> choices that cannot be described as anything much better than random subjective choices by the persons who do the analysis.
Of course they can be describe better than that, Pekka.
You’re just lazy.
Williard,
Many choices can be described better, but I do, indeed, believe that there are several model parameters, that cannot be determined based on objective criteria accurately enough to avoid the problem. Practical work with models tells that they are often sensitive to parameters that cannot be determined objectively without the need of “random” subjective choices at some step of the determination.
Examples of such parameters enter typically in description of future technical development. That’s very often modeled including endogenous learning. Past data cannot tell well, how that should be parametrized, but the long term result are very sensitive to that. Many other submodels are equally problematic.
Jsam/Pekka (apologies for the Peeka!)
thanks for the refs. I’ve had a cursory skim, will try to find some more time later.
Essentially it seems that the use of discounting at all is not obviously the best way to evaluate long term, high impact decisions, let alone the rate.
Even the much criticised 1.4% I believe Stern used may even be too high.
My analogy: National Parks. I’m sure that no economic analysis based on discounting would justify anything other than massively more development than is the case now. However, we still *choose* to protect these areas of natural beauty.
Discounting the future is just what it says. Flip it over. Is the past worth *more* than now? Really?
The dismal science indeed…
jsam, suppose we had an operational, zero cost time machine, so that we could in fact intervene in the past. Economists may well consider investments with a monetary return in the past more valuable than those today, by an amount representing the return on the investment today. However, for actions in the past changing the lives of people in the past, but not those today they would probably discount their monetized value.
Here’s what British philosopher, Derek Parfit, has to say about the discount rate:
and a bit later he says:
Source: http://faculty.smu.edu/jkazez/parfitsocialdiscountrate.pdf
Part, a large part, of the cacaphony is that there are several discount rates. Stern spent a considerable amount of print discussing this in setting a very low social discount rate which incorporates other values besides market economics. Tol was a virulent (too soft a term) denier of this point until Weitzman (sp?) pointed out tail risk whereupon he softened.
IEHO, given the time horizon of the problem, economic models simply fail. Economic models are useful in treating immediate choices, e.g., this or that, or even 5-15 year investment decisions, but they simply fail on the longer term because they cannot handle technological developments and sheer human cussidness amongst other things.
> Such a “social discount rate” seems indefensible to me [Derek Parfit].
Derek Parfit may not be as good as Richard to boost and boast his topness, but ninjas that know that philosopher a bit may allow themselves to say, within their bosoms or perhaps sotto voce: ouch.
Of course we do adopt de facto spacial discount rates. It’s just a bit embarrassing to talk about them in such terms.
A good example is those who can most afford insurance setting climate policy based on insured damages.
Morals and ethics are an odd ground, and at this point a very undefined quality. So much so, that I’m surprised that the denial circuit didn’t just start with it. On the other hand I guess they know how their arguments would look. “Let those Africans suffer! Who cares?”
Its a relatively new concept for one man to be concerned about another. This is an issue discussed at great length in Kenneth Clark’s ‘Civilization’. I recommend you go to your library get this out and give it a watch.
http://www.theguardian.com/media/2011/jan/20/kenneth-clark-civilisation-bbc-hd
The final bit recaps how each age would have treated a downtrodden fellow man. Worse, most people don’t remember where those values came from… Christian Church cared about your soul, not your body. To let a common man die was no crime. How does that play in an age of atheism?
As I’ve already mentioned Moncton touches on this in his appeals for a ‘Fox Australia’. (Can you guess what kind of humanity he is appealing for?)
AnOilMan,
Morals and ethics are an odd ground, and at this point a very undefined quality.
I’m not really sure what you mean by this so my response to your comment might be totally wrong, but I’m going to comment on what I think you mean. There are many very good philosophers who do argue that objectivity and universality exists in ethics. Derek Parfit recently published an enormous book titled On What Matters in which he argues exactly this. Here’s an excerpt, not from the book but from a review of the book:
There’s also quite a bit written about the origins of ethics and how it likely stems from kinship and reciprocity, both of which can be found in other animals.
I haven’t studied the subject, but it seems to come up from time to time. I feel that most people run on automatic (subconscious drives) unless something snaps them out of it. (A key word to look for is ‘should’ it implies a lot of preconceived values about priorities. Yet most people aren’t aware they are even using it, let alone why. ‘You should do this..’ )
I don’t think ethics are universal, and I do think that they are at the core of opposition to Climate Change.
The notion of harming others is a key component in ‘The Authoritarians’, simultaneously enabling them to inflict harm while experiencing suffering more than others; (He is discussing the political groups with the strongest opposition to Climate Change. Their motivations and logic are different from what you might think.)
https://home.cc.umanitoba.ca/~altemey/
I am not saying that I don’t care… But in an age where Rwanda occurred, and is occurring again in the Central African Republic (today, now). I think the definition of good and bad ethics are questionable. I think that how strongly we respond to it, is also questionable.
Terry Jones (Medieval Lives) discusses opposition to violent gladiatorial fighting to punish criminals in Rome, it was something like, “Where is the sport in that? There’s no challenge.” Something has most definitely changed since then.
The point I have tried to make is a separate one from that of the just social discount rate, but it may affect the ultimate conclusions. It’s related to the automatic and unavoidable adaptive processes and their influence on the persistence of the actual effects. I’m much more experienced in bottom-up than in top-down thinking. Therefore I have tried to figure out, how the issue I consider might be already taken into account in top-down approach, but with best effort I have not found such an explanation.
Neither have I found the point discussed explicitly elsewhere, although I consider it so obvious that it should have been realized by many. It’s related to some arguments made in support of higher operational discount rates, but lacking explicit discussion the full answer is left open. Making some simplifying assumptions I should be able to express the point mathematically, and to derive quantitative conclusions for the simplified cases. I try to write a systematic presentation of both my interpretation of the results of papers like that of Fleurbaey and Zuber, and of the influence my proposal has on those. (As part of that, I think it’s possible to extract the essential assumptions and mathematical interdependencies of Fleurbaey and Zuber in a concise and clear way.)
Another issue that has also some relationship with what I have in mind is discussed by Kandlikar and Morel: Accelerating the Mitigation of Greenhouse Gas Emissions: The Influence of Uncertainties in Economic Growth and Technological Change, but this is, again, not exactly the same.
If I succeed in my plans I’ll write my results up and bring them to public in some way, probably on net, but possibly as a scientific paper. It’s quite possible that I’ll still find some sources where the points are already discussed. Commenting on those sources on the net would then be the obvious choice.
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Do not ask for whom the bell Tols, it Tols for free, http://stickmanscorral.blogspot.no/2014/04/on-economic-consensus-and-benefits-of.html.
I’m all Donne now.
Tol amplified in the anti-science of Forbes. http://www.forbes.com/sites/timworstall/2014/04/25/the-scientific-consensus-is-that-were-doing-too-much-about-climate-change-not-too-little/
Tim Wolstall, no less. http://www.sourcewatch.org/index.php/Adam_Smith_Institute – more tobacco industry connections.
The stickman blogpost linked above by jsam is very interesting. It gives as a best fit formula for the costs of climate change as shown in Fig 10 of IPCC WG2 the formula:
D = 0.01T – 0.27T^2
At 2.5 C, that works out at damages of -1.66% of GDP, compared to the -0.2 to -2 C quoted by the IPCC. The 95% confidence interval at 2.5 C is approximately +/- 1.2% (as determined by pixel count), giving a range of -0.44 to – 2.86%, substantially larger than that determined from studies at 2.5 C alone.
Given that Tol has lead the way in determining best fit cost curves from multiple study reviews, I am puzzled as to why the IPCC dropped his propensity to determine the best fit curve on that point – particularly when they take the odd approach determining the costs at just one temperature value, a peculiarly useless approach, and one, it turns out, that by ignoring 60% of the data points, provides a reduced cost range.
More on Tolgate today, http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/apr/30/economics-clear-need-climate-action
Mr (he’s not keen on using Dr, apparently) weighs in in the comments – not very mightily it must be said. 🙂
Fascinating. Possibly a classic example of how to attempt to de-legitimise those who disagree with you. Play the ball, not the man springs to mind 🙂
Way back when I was in university we had a ‘professor’ who was tossed out for faking data. Some folks were asking for data from (invented) studies cited.. when it didn’t appear, it snow balled into a lot of quackery.
Hunting this stuff down is part of the result of peer review. Its published, now he has to defend it in as much as it means. i.e. provide the data.
At this point… I want to see the data. I want to know it wasn’t faked.
Tol has prior. http://www.thejournal.ie/esri-paper-unemployed-dole-richard-tol-484632-Jun2012/
And, buried away in the comments, “In the long run, all studies find net negative impacts.” So, despite the dust thrown in readers’ eyes, there is, indeed, a problem to fix.
—
RichardSJTol JJRichardson
01 May 2014 10:31am
There are positive and negative impacts of climate change.
A number of studies find that the positives outweigh the negatives in the short run. Other studies find the opposite.
In the long run, all studies find net negative impacts.
—
http://discussion.theguardian.com/comment-permalink/35058422
jsam,
I saw that and, if I could have been bothered, I was tempted to ask Richard if he understood the concept of inertia. We’ve already pretty much done enough already to almost guarantee that we’ll get to the point where most economic models suggest negative impacts.
Mr Tol is selective as to which queries he responds to. To “are your methods on display” he responds “the data is available”. You may have saved yourself some bits by not bothering to ask a question that would go unanswered. 🙂
jsam: Data is available on asking questions after all…