1. There is another consensus estimate in ERL. Carlton et al. interviewed 698 natural scientists at 10 universities in the USA about climate change. The paper is called "[t] climate change consenes extends beyond climate scientists". This undermines the earlier papers by Anderegg et al. and Verheggen et al., who reach a high consensus only by excluding non-experts.

    Carlton et al. highlight their consensus estimate of 92%. This is based on two questions:
    1. When compared with pre-1800's levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant? (93% say risen)
    2. [if risen] Do you think human activity is a significant contributing factor in changing mean global temperatures? (97% agree)
    Note the ambiguity of the words "significant" -- it does not indicate anything about the size of the human contribution -- and "human activity" -- which includes greenhouse gas emissions, land use change, etc etc etc. 

    Carlton et al. do not cross-check the above result with three other questions.
    1. Variation in solar activity is responsible for the majority of the observed warming in the past century. (9% agree)
    2. Higher emissions of greenhouse gases will lead to greater atmospheric warming. (95% agree)
    3. Climate change is independent of atmospheric carbon dioxide levels. (5% agree)
    The second question is intriguing: In equilibrium, temperature is roughly proportional to the logarithm of the atmospheric concentration of carbon dioxide. That implies that an increase in emissions will lead to less additional warming. When read as a second derivative, 95% of respondents are wrong but when read in a colloquial way, 95% of respondents are correct. I double-checked with the lead author. Carlton tells me that this was not picked up in the pre-test.

    Carlton also tells me that 53 of the 55 people who claim that solar activity is responsible for the observed warming also believe higher greenhouse gas emission lead to greater warming -- and that 31 of the 55 also believe that human activity is a significant factor.


    It seems to me that a substantial share of the respondents did not take the survey very seriously, that the authors did not dig very deep, and the referees were not paying attention either.
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  2. I submitted the following to the Climate Spectator on Nov 13, after several attempts to get in contact with the editor.

    On October 3 and again on October 23, the Business Spectator published articles by Mr Robert E.T. Ward BSc criticizing my work. Mr Ward is a public relations professional in the employ of Lord Stern of Brentford. He is without formal qualifications in economics, the subject matter of his criticism. Although Mr Ward has been invited to publish his concerns in the academic literature, he has chosen the popular media instead.

    Mr Ward raises many trivia. I here focus on the two points of contention. First, Mr Ward disputes that climate change might have positive impacts. Such impacts are well documented and straightforward. Warmer winters imply lower heating costs and reduced cold-related illness. More carbon dioxide in the atmosphere means that crops grow better, particularly in dry areas. A number of studies have concluded that these positive impacts are larger than the negative impacts, at least for modest climate change. Mr Ward has not disputed these studies – instead he has targeted my work which merely summarizes earlier findings. In my latest synthesis, I reckon that incremental impacts will turn net negative in the near future. Indeed, that paper concludes that greenhouse gas emissions should be taxed.

    Second, Mr Ward disputes that the impacts of climate change on human welfare are not large. The Stern Review estimates that climate change would make the average person feel as if she had lost five to twenty percent of her income. Other studies find lower numbers. Twenty per cent may seem like a lot, but it is the impact of a century of climate change. Put in context, a century of climate change is about as bad as losing a decade of economic growth – or as bad as lowering the economic growth rate from 2.0% to 1.8% per year. That is by no means trivial – but it is not very large either compared to, say, the economic crisis in Greece. Similar estimates of the welfare impact of climate change have been reported in the last four reports of the Intergovernmental Panel on Climate Change and are shared by other economists, including Mr Ward’s colleagues Professors Fankhauser and Stern. This basic finding is supported by a large technical literature, but it is also in line with casual observations. If we compare hot and rich Singapore to the hot and poor Congo, cold and rich Sweden to cold and poor Mongolia, then we realize that climate is not a fundamental driver of economic well-being. Climate change is a problem, but we should not lose perspective.

    Mr Ward’s concerns are without merit.


    On Nov 24, Tristan Edis announced the discontinuation of this publication.
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  3. This is beginning to feel a bit like the Stern Review, with its endless appendices and postscripts, and addenda (with appendices) to the annexes. Did I ever write that we discovered an error in Simon Dietz' spreadsheet that inflates many results in the Stern Review by one-third? I never spotted the erratum for that one.

    Anyway, Environmental Research Letters came back with comments on my latest attempt to get something published about Cook's 97% paper. They were much quicker this time, but as before they argue that critical debate is not something academics do. I kept my questions, see whether they survive another round of review.

    Update (30 Oct 2015): Paper accepted.

    Update 2 (25 Jan 2016): I did not realize that that acceptance was only informal. It's formal now.
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  4. Mr Robert E.T. Ward BSc, Policy and Communications Director of the Grantham Research Institute on Climate Change and the Environment, recently published a piece about my work under the title “Flawed analysis of the impacts of climate change”. Mr Ward raises two main objections, first, to the conclusion that “the overall impacts of unmitigated climate change this century could be positive, even if global average temperature rises by more than 2°C above its pre-industrial level” and, second, to the conclusion that “the welfare change caused by climate change is equivalent to the welfare change caused by an income change of a few percent”.

    Let us consider Mr Ward’s objections in turn. Climate change will have many, diverse impacts and it will affect different people in different ways. Some of these impacts are negative, some may be negative or positive, and some are positive. The three key positive impacts are a reduction in the costs of winter heating – a particular boon to the poor in temperate and cold climates – a reduction in cold-related mortality and morbidity – a particular boon to the old and frail in temperate and cold climate change – and an increase of carbon dioxide fertilization – a particular boon to those dependent on water-stressed agriculture. The last effect is more immediate because it depends on the atmospheric concentration of carbon dioxide rather than the consequent climate change.

    Twenty-two studies of the total impact of climate change on human welfare have been published and four of these – by the late Professor Ralph d’Arge, Professor Robert Mendelsohn, myself, and Professor David Maddison – show that the net impact of modest global warming may be beneficial. Mr Ward’s protestations notwithstanding, this finding is well accepted in the academic literature – and indeed Mr Ward fails to cite a single dissenting paper.

    Mr Ward's focus on the total impact betrays his lack of formal education in economics. What matters is not whether the total impact is positive or negative, but rather when the incremental impacts turn negative. My latest estimate puts that at 1.1°C global warming relative to pre-industrial times, or some 0.3°C warming from today. That cannot be avoided – unless we believe that the climate sensitivity is much lower than commonly found, and we believe that governments are secretly plotting much more drastic emission cuts than those announced. The initial benefits are thus sunk. The corresponding policy intervention is a Pigou tax*, rather than a Pigou subsidy. Greenhouse gas emissions should be reduced.

    Mr Ward’s second objection is equally unfounded, and again he does not cite any study that contradicts what I wrote. The twenty-two studies cited above all agree that the impact of climate change is small relative to economic growth. This was found in studies by Professor William Nordhaus and Professor Samuel Fankhauser. It was confirmed by the Intergovernmental Panel on Climate Change from its Second Assessment Report, in a chapter led by the late Professor David Pearce, to its Fifth Assessment Report, in a chapter led by me. Even the highest estimate, the 20% upper bound by Lord Professor Nicholas Stern of Brentford, has that a century of climate change is not worse than losing a decade of economic growth.

    Over the years, many people have objected to these estimates. Tellingly, not a single one of these people have published an estimate that strongly deviates from existing estimates. On the contrary, a number of people have set out to prove Nordhaus and Fankhauser wrong, only to find estimates of a similar magnitude.

    In sum, climate change is a problem but not the biggest problem in the world. It is good to keep perspective. At the heart of the current problems at Volkswagen lies a system of regulations that prioritizes one problem – carbon dioxide emissions – at the expense of another – particulate emissions. Environmentalists’ relentless focus on a single simple message may be an excellent strategy for fund-raising, but it makes for poor public policy. Incomplete and imperfect as our understanding of climate change and its impacts may be, Mr Ward’s dismissal of the evidence is not the best way forward. Academic inspiration, it gave me none.

    *unless you want to argue that climate change is the mother of all externalities, in which case we need a Lees Tax, after Pigou's mother.
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  5. The Cook saga continues.

    Inspired by Ben Dean's success in getting an ever-so-mildly critical comment published in Environmental Gatekeeping Research Letters, I submitted a short note with a few critical questions myself.

    It took 6 months to review this, a week to revise the comment.

    As before, ERL shows an aversion to hard questions. The referee also complains that it has been over two years since Cook's paper was published, seemingly oblivious to the great delays the journal incurs.

    The referee also asked me to place Cook's results in the context of other estimates of the rate of the agreement on the hypothesis that most of the observed warming is due to anthropogenic greenhouse gas emissions. That was a bit of an eye-opener. Like many others, I had believed Cook that his result was in line with other estimates. It is not.
    Figure 1. Estimates of the consensus on anthropogenic global warming according to Cook et al. and other studies (Bray, Oreskes, Doran, Anderegg, Stenhouse, Verheggen) as a function of the sample size.
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  6. This September marked the 10th anniversary of David Pearce's death. He died as I was in transit to Princeton. I recall the shock. Just the week before, I had spoken to a very lively Pearce about what turned out to be his final paper. Like so much of David's work, it was prescient: It warned that UK climate policy had been hijacked and transformed into a policy that did not aim to reduce emissions but rather to create rents for special interests groups.

    I learned a number of things from David. He was a keen environmentalist, but he never exaggerated his estimates. Environmental problems are big enough as they are. If the analysis shows that a problem is small, then there are plenty of other, bigger problems to worry about. There is enough real trouble in the world. No need to add imaginary worries.

    David made a career of suggesting solutions to environmental problems but he hoped -- against hope, he knew -- to end that career, his job obsolete, in a restored environment and spend many leisurely years enjoying the beauties of nature, Instead, the cancer got him.

    David also believed that academic integrity is more important than political expedience. He was not impressed when the IPCC decided to throw us under the bus rather than defend our chapter on the social costs of climate change against the trolls, nor when Pachauri did a runner. Policy advice should be based on our best estimates of how the world is, rather than on what we'd like the world to be, or on what political correctness dictates we should think about the world.

    David also emphasized perspective. He would have been aghast at learning that our vehicle regulations have allowed companies like Volkswagen to focus on one problem -- carbon dioxide emissions -- at the expense of another problem -- particulate emissions. Energy and transport create and solve many problems, and only by considering them all together can we hope to find a reasonable solution.

    David once told Sir Crispin Tickell that "being alone does not make you wrong, but it should make you think" -- this in response to Sir Crispin's extreme position on the discount rate.

    David always thought, whether he was alone or not. He rarely stood alone, but was never afraid to. One of my fondest memories is how he took on a room of hostile environmentalists attacking our estimates for the IPCC, patiently and politely skewering all the arguments thrown at him.

    Environmental economics and public policy are worse without him -- but so much better than if he had chosen a different career, teaching many others besides me about policy analysis.


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  7. I grew up in an environment where people were deeply Catholic but did not like the Church very much. I guess that rubbed off on me.

    The Pope has released an Encyclical on Care for our Common Home. It is rather long. It has good things. It has bad things. I do not like mystical waffle about Mother Earth, and I'm troubled by Earth being both mother and sister -- we should strive to be like God after all. I do not like the blending of Mary with Pachamama and Gaia. I am not impressed by normally a- or anti-religious intellectuals who suddenly discovered their inner papist. But let's focus on what Pope Francis has to say about climate change and climate policy.

    Para 23 is all a bit strange, hopefully explained by inexpert translation from Italian to English. Climate is a commons good, for instance, rather than a common good*; and we normally refer to "land use change" rather than "changed uses of the soil". Carbon dioxide is referred to as pollution, which is a nonsense (outside the US legal system). Para 24 offers the alarmist claptrap you would expect to find in a Greenpeace magazine. See the response in the Catholic Herald.

    Para 25 suggests that the poor are vulnerable to climate change because of where they live. Actually, they're vulnerable because they're poor. The Pope misdiagnoses, and thus recommends the wrong treatment. Economic growth is the prime strategy against the disproportionate impacts of climate change on the poor.

    Paras 54 & 56 make strange claims about the nature of capitalism and international relations, and para 57 raises the prospect of resource wars. This is the stuff of failed undergrad essays.

    Para 61 uses the tired rhetoric 'happy to talk to anyone who agrees with me' reinforced by the exclusive "people of good will" in Para 62.

    Chapter Two argues for stewardship and against dominion; and extends the Sacrament of the Holy Communion to non-humans (!) Chapter Three identifies anthropocentrism as the root of all evil. Chapter Four does not seem to do anything much, but Three and Four together are very cautious about new technologies, including social media. The Church remembers Gutenberg. There is also a strong sense of distrust in free markets - a recent invention that eradicated so much poverty and power. See the response in the New York Times.

    Chapter Five has policy recommendations. Unsurprisingly, the Catholic Church is ardently internationalist: It sees itself, after all, as the successor to the Roman Empire.

    In Para 170, Pope Francis comes out in favour of environmental taxes, but rejects uniform taxation because of differences in the ability to pay between countries. Oddly, the same reasoning is not applied to the differential impacts of environmental taxes between rich and poor within countries.

    Para 171 argues against tradable permits because markets can't be trusted.

    Para 175 calls for the eradication of poverty, but without acknowledging that energy access is a key part of that, and thus without realizing that climate policy may stand in the way of poverty eradication.

    Chapter Six calls for a new spirituality, humans in harmony with their environment.

    Overall, this is a disappointing encyclical. No one is waiting for the hare-brained social theories of the Catholic Church. The Pope can provide moral guidance, but the passages on intergenerational justice are mostly waffle. Laudato Si does not even recognize a key moral dilemma - both climate change and climate policy disproportionally hurt the poor - let alone offers a way out.

    The real fireworks are in Chapter Two. Universal Communion? Wow!

    *Joseph Heath reminds us that Catholic social theory uses "common good" to refer to what economists call social welfare.
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  8. In de aanloop naar de onderhandelingen in Parijs wordt er weer veel over klimaatbeleid geschreven. De onlangs gepensioneerde hoofdredacteur van het Engelse Guardian, Alan Rusbridger, bedacht een campagne om zichzelf de geschiedenisboeken in te schrijven: Verkoop je aandelen in energiebedrijven en fossiele brandstoffen blijven in de grond! Het is geen groot success. Tegenover elke verkoper staat een koper. Milieubewuste investeerders zijn er niet veel, rendementjagers des te meer. Als we Rusbridger’s advies volgen wordt het groene pensioen minder waard, en het bruine pensioen meer. De uitstoot blijft zoals het was.

    Anderen beweren dat de markt voor fossiele brandstoffen op instorten staan, en dat een verstandige belegger zich uit de voeten maakt. “Wegwezen voor de koolstofbubbel barst” kopte Trouw afgelopen Maandag. De klimaatdoelstelling van de Verenigde Naties – de Aarde mag niet meer dan 2 graden opwarmen – vereist inderdaad een spoedig afscheid van steenkool, olie en gas. Maar dat betekent niet dat er een zeepbel is in de energiemarkt.

    De markt kan rare sprongen maken. De prijs kan de waarde een tijdlang ver ontstijgen – zoals bijvoorbeeld met tulpenbollen in 1637 of met huizen in 2008 – totdat de markt plotseling instort. Soms zitten speculanten achter een zeepbel, soms is er kuddevorming onder kopers, en soms wordt de markt verrast door nieuwe informatie. Het verhaal achter de koolstofbubbel gaat als volgt. De regeringen van de wereld staan op het punt stringent klimaatbeleid af te spreken. Investeerders weten hier niets van, en worden op 12 December wakker in een wereld waarin fossiele brandstoffen waardeloos geworden zijn omdat de onderhandelingen in Parijs een groot succes waren.

    Dit verhaal is onwaarschijnlijk. De ontwikkelingen in het internationale klimaatbeleid gaan langzaam, en worden nauwlettend in de gaten door het bedrijfsleven. De kans is groot dat Parijs mislukt zoals eerder Kopenhagen mislukt is. De tijd dat een kleine groep milieuradicalen het Europese energiebeleid naar hun hand konden zetten is voorbij: De Engelsen en Duitsers hebben hun enthousiasme voor wind- en zonneenergie verloren, en Zuid- en Oost-Europa hebben nooit veel gevoeld voor het klimaat. Frankrijk wil graag, maar eigenlijk alleen om dat le Protocole de Paris zo mooi klinkt. Brazilie, China, India, Japan, en Rusland staan niet te springen om een aanscherping van het klimaatbeleid, en zijn wars van bindende internationale afspraken. President Obama wil wel, maar kan de Senate niet overtuigen een verdrag te ondertekenen. Parijs wordt de begrafenis van de twee-graden doelstelling.

    Er is nog een andere reden dat klimaatbeleid geen grote deuk zal maken in de winstgevendheid van energiebedrijven. De grootste bedrijven zijn staatseigendom, zeker in olie en gas: Saudi Aramco, Sinopec, Gazprom, Petrobras, Pemex. De rest betaalt winstbelasting. Hun werknemers betalen inkomstenbelasting. En daarbovenop worden royalties geheven op het winnen van steenkool, olie en gas. Als er een zeepbel is, en als die knapt, dan is de belastingdienst een van de eerste en grootste slachtoffers. En als pensioenfondsen veel geld verliezen, dan zal de stemmer eisen dat de overheid bijspringt. Zal de regering zichzelf zo in het vlees snijden? Zal het Ministerie van Financien toestaan dat het Ministerie van Milieu een gat slaat in de belastingopbrengsten?

    Zelfs als dit allemaal niet waar is, als de Verenigde Naties onverwachts een streng klimaatbeleid af kunnen dwingen tegen de wensen van de ministeries van financien in, dan is er nog steeds geen reden om Koninklijke Olie te verkopen. De marktwaarde van een bedrijf wordt bepaald door de verwachte winst in de komende paar jaar. De winstverwachting in de verdere toekomst wordt zwaar verdisconteert.

    Olie-, gas- en kolenbedrijven verdienen weinig geld met het eigendom van energiereserves, of eigenlijk exploitatielicenties. De winst zit in hun core competence: de financiering van lange termijn investeringen met een hoog risico, en in het beheren van reusachtige en gecompliceerde projecten. Die expertise en ervaring verdwijnt niet als we ineens geen koolstofdioxide meer uit mogen stoten. Integendeel. In dat geval hebben we lange termijn en riskante investeringen nodig in reusachtige en gecompliceerde projecten voor koolstofvrije energie.

    De koolstofbubbel is een broodje aap. De milieubeweging is erg dol op dit soort onzin. Malthus heeft al 217 jaar ongelijk, Paul Ehrlich al 47 jaar en de Club van Rome al 43 jaar – maar dat is nog niet tot onze groene vrienden doorgedrongen.

    Het gaat zeker nog 50 jaar duren om het klimaatprobleem op te lossen, en misschien wel 100 jaar. De benodigde investeringen gaan tot in de tientallen biljoenen euro lopen. Klimaatbeleid is een serieuze zaak en het is gedoemd te mislukken zonder de medewerking van de financiele sector. Loze praatjes over een koolstofbubbel doen het leuk voor een algemeen publiek, maar tasten de geloofwaardigheid van de milieubeweging aan. Als de sommen over klimaatbeleid zo erg de mist in gaan, zijn de sommen over klimaatverandering dan wel te vertrouwen? Gezien de schaal van het klimaatprobleem lijkt het raadzaam dat de milieubeweging zich met de gepaste verantwoordelijkheid opstelt.

    Een licht geredigeerde versie verscheen op 6 Juni 2015 in Trouw.
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  9. I enrolled in Denial101x, partly to see what MOOCs are all about and partly to see what Cook and co were up to now.

    Production values are high. The videos are slick, and well-integrated with surveys, discussion forums and quizzes to test how well you understood the material.

    The contents are poor. The title is a start. "Denial" is a deliberate provocation, used to reinforce the tribal identities that polarize the climate debate.

    The opening survey was full of leading questions, and the accompanying quizzes are not much better. As an example, students are asked to pass judgement on parents who choose against vaccination. Little information is giving about the situation. Parents may opt out of vaccination because they are confused about its pros and cons, or because vaccination conflicts with their religious beliefs, or because they have superior knowledge of their child's medical condition. Who knows? However, students of this course are led to believe that anti-vaxxers are like Holocaust deniers.

    As another example, students are asked to judge the size of the urban heat island effect, again without providing much context. The world has warmed by some 0.8K on average since the start of the industrial revolution. Cities are 2-4K warmer than the surrounding countryside. Is that large or small? Cities occupy only a tiny fraction of the planet's surface, so if area is your frame of reference, the urban heat island effect is not that important. On the other hand, more than half of all people live in cities, so if population is your frame of reference, the urban heat island effect is a lot bigger than greenhouse warming. And, as thermometers tend to be where people are, the urban heat island effect is quite an important factor when homogenizing temperature records. Such nuances, so common in a university education, are absent in Denial101x.

    I guess this comes as no surprise as the team behind Denial101x is the team behind SkepticalScience, that is, a bunch of none-too-bright rabid environmentalists.

    It is a surprise, at least to me, that the University of Queensland and edX lend their name to this. I inquired with edX, and they confirm that quality control is not their thing. Indeed, they are not even bothered when lecturers seem unsure about their qualifications and employers. The course leader does not have a PhD, and in the first two weeks we saw a climatologist lecture in psychology and a chemist lecture in climatology. A bad advertisement for MOOCs.

    As an aside, after my course on Climate Economics, one of the students asked me where I stood on the politics of it all.
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  10. A full reconstruction of Cook's 97% nonsensus is still lacking. However, Sou of Bundanga may have unraveled one further mystery.

    In the data that Cook made available, abstract IDs run from 1 to 12,876. The paper says that 12,465 abstracts were downloaded, of which 11,944 were used.* So, 411 abstracts are unaccounted for. 411 is a large number relative to the number of papers that drive the alleged consensus, but not knowing why the 411 were missing, I only included a puzzled footnote in my Energy Policy paper.

    Here is an explanation. Cook downloaded the abstracts from the Web of Science in two batches. The first batch was the largest. After they had rated all that, there were a good few more recent publications, so a second batch of abstracts was downloaded.

    There was overlap between the first and second batch, and 411 duplicates were removed. So far, so uncontroversial.

    However, if Sou is to be believed, duplicates were removed from the FIRST batch, already rated, rather than from the second batch.

    The missing abstracts are indeed disproportionally concentrated among the lower IDs, which is consistent as the default data dump from the Web of Science presents the more recent papers first, and more recent papers are much more likely to overlap in Cook's two data dumps.

    By removing already rated abstracts, Cook created more work and denied an opportunity to test data quality.

    More importantly, Cook replaced ratings from the first rating period with ratings from the second rating period. These ratings are markedly and significantly different. It appears that Cook moved some 40 abstracts from category "3" to "4", again reducing the consensus rate down to 97%.

    UPDATE
    Sou offers an alternative explanation. Apparently, Cook queried WoS and downloaded the data in chunks. Some chunks were downloaded twice, or perhaps they were uploaded twice into Cook's database. For this explanation to work, we would have to believe that the data chunks were as small as 342 abstracts, or even 63 abstracts, or maybe even 4. Recall that Cook had 12,000+ abstracts.

    Alternatively, Cook may have split his query, e.g. by discipline. This would lead to sizable data chunks, but the pattern of overlap would be random. Cook's overlaps are concentrated: According to Sou, the missing IDs are:
    • IDs 5 to 346 inclusive = 342
    • IDs 1001 to 1004 inclusive = 4
    • IDs 2066 to 2128 inclusive. = 63
    • Total = 409 - the other two are probably isolated somewhere.

    I find all this implausible. If true, it would explain why my query returns 13,431 papers, but Cook has only 12,465 papers in his data: Some data chunks were downloaded but not uploaded.

    *Brandon Shollenberger drew my attention to the discrepancy.



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