Warm oktoberweer, maar geen opwarming

Chemicus en statisticus Frans Dijkstra publiceerde gisteren in de Volkskrant een opiniestuk naar aanleiding van het warme weekend. De kop in de krant was dezelfde als boven dit blogbericht. Die kop is overigens bedacht door de Volkskrant, niet door Dijkstra, liet hij me weten. Online staat er trouwens een andere kop: Het publieke weergeheugen werkt misleidend.

Op twitter reageerde Stephan Okhuijsen van Sargasso.nl vrij gepikeerd en hij plaatste al snel een kritische beschouwing die als titel had: Liegen met grafieken: geen opwarming in de Volkskrant.

Frans Dijkstra gaf me toestemming om zijn stuk door te plaatsen. Daaronder probeer ik iets weer te geven van de discussie. En hopelijk kan een constructieve discussie tussen Dijkstra, Okhuijsen en andere geïnteresseerden meer duidelijk scheppen over welke “correcte” conclusies nu te trekken zijn.  Lees verder…


IPCC bias in action

The AR5 Synthesis Report has been published with all the usual rhetorics such as that we have only so much years left to act. Readers here know that my interest with regard to AR5 has been climate sensitivity. So let’s just shortly review what happened in the field of climate sensitivity between the Synthesis Report (SYR) of AR4 (2007) and that of AR5 (2014). Let’s focus on the SPM because this is what is supposed to be the most policy relevant information.

The SYR SPM of AR4 mentions “climate sensitivity” seven times:

For GHG emissions scenarios that lead to stabilisation at levels comparable to SRES B1 and A1B by 2100 (600 and 850 ppm CO2-eq; category IV and V), assessed models project that about 65 to 70% of the estimated global equilibrium temperature increase, assuming a climate sensitivity of 3°C, would be realised at the time of stabilisation. [Figure SPM.8 on page 12]

The timing and level of mitigation to reach a given temperature stabilisation level is earlier and more stringent if climate sensitivity is high than if it is low. [page 20]

Global average temperature increase above pre-industrial at equilibrium, using ‘best estimate’ climate sensitivity [Table SPM.6 on page 20]

The best estimate of climate sensitivity is 3°C. [note d of table SPM.6 on page 20]

Equilibrium sea level rise is for the contribution from ocean thermal expansion only and does not reach equilibrium for at least many centuries. These values have been estimated using relatively simple climate models (one low-resolution AOGCM and several EMICs based on the best estimate of 3°C climate sensitivity) and do not include contributions from melting ice sheets, glaciers and ice caps. [note f of table SPM.6 on page 20]

The right-hand panel shows ranges of global average temperature change above pre-industrial, using (i) ‘best estimate’ climate sensitivity of 3°C (black line in middle of shaded area), (ii) upper bound of likely range of climate sensitivity of 4.5°C (red line at top of shaded area) (iii) lower bound of likely range of climate sensitivity of 2°C (blue line at bottom of shaded area). [Caption of figure SPM.11 on page 21]

Impacts of climate change are very likely to impose net annual costs, which will increase over time as global temperatures increase. Peer-reviewed estimates of the social cost of carbon23 in 2005 average US$12 per tonne of CO2, but the range from 100 estimates is large (-$3 to $95/tCO2). This is due in large part to differences in assumptions regarding climate sensitivity, response lags, the treatment of risk and equity, economic and non-economic impacts, the inclusion of potentially catastrophic losses and discount rates. [page 22]

Climate sensitivity is a key uncertainty for mitigation scenarios for specific temperature levels. [page 22]

Summarised: climate sensitivity and its uncertainties is highly relevant for the amount of future warming. The best estimate for climate sensitivity is 3°C, the lower bound is 2°C and the upper bound is 4.5°C.

The full AR4 Synthesis report mentions climate sensitivity 13 times. It for example said:

Progress since the TAR enables an assessment that climate sensitivity is likely to be in the range of 2 to 4.5°C with a best estimate of about 3°C, and is very unlikely to be less than 1.5°C.


Now straigth to the AR5 Synthesis Report SPM. It mentions this highly relevant parameter (according to AR4) … zero times! Not a word about it. The full Synthesis report does mention it four times. For example on page SYR-23 we read:

Climate system properties that determine the response to external forcing have been estimated both from climate models and from analysis of past and recent climate change. The equilibrium climate sensitivity (ECS) is likely in the range 1.5 °C–4.5 °C, extremely unlikely less than 1 °C, and very unlikely greater than 6 °C.

Now what has happened in the past seven years that climate sensitivity disappeared from the SPM of the Synthesis Report? Has it become irrelevant? Of course not. Climate sensitivity is all over the Synthesis Report because the models used to project the future climate have a climate sensitivity of about 3.5°C on average. So in all its projections IPCC assumes climate sensitivity is still >3°C. It’s there as some sort of hidden assumption.

Why not say so then? Well, exactly this assumption, that the model climate sensitivity is about 3.5°C, has been seriously challenged in the past few years in the scientific literature. The Lewis/Crok report A Sensitive Matter (published in March of this year) gave all the details about new observationally based studies that indicate the climate sensitivity is relatively low with best estimate values of between 1.5 and 2°C. Considerably lower than the 3.5°C climate sensitivity of the models.

Recently Lewis and Curry used all the relevant AR5 numbers and a very detailed uncertainty analysis to estimate the range and best estimate for climate sensitivity in a paper published in Climate Dynamics. Their preferred likely range is 1.25-2.45°C and the best estimate is 1.64°C. Again, these are not numbers invented by skeptics, those are the numbers of the IPCC itself. It assumes close to 100% of the warming since 1850 is due to humans, an assumption that goes much further than the iconic “it’s now extremely likely that most of the warmings since 1950 is due to humans” statement in AR5.

Now this specific paper of course came out after the IPCC deadline for the Synthesis Report. However as we document in the Lewis/Crok report, the IPCC was well aware of these recently published lower estimates of climate sensitivity. It lowered its lower boundary from 2°C back to 1.5°C (where it has been in most earlier IPCC reports).

The IPCC was saddled with a dilemma. A lot of conclusions in the report are based on the output of models and admitting that the models’ climate sensitivity is about 40% too high was apparently too…inconvenient. So IPCC decided not to mention climate sensitivity anymore in the SPM of the Synthesis Report. It decided to give the world a prognosis which it knows is overly pessimistic. One may wonder why. Did it want to hide the good news?


Climate Dialogue about the sun

Over at Climate Dialogue we are starting a new discussion about the influence of the sun on the climate. People familiar with climate discussions know that the sun has been and still is a popular argument against the large role for greenhouse gases. This has to do with solar proxies correlating well with climate proxies (in the distant past). Also the Little Ice Age coincided with the Maunder Minimum, a period with few visible sunspots. So if the sun played a role in the past, why shouldn’t it in the present?

But figuring out how the sun has varied in e.g. the past millennium isn’t easy. And in fact, the science seems to be developing in the other direction, i.e. showing an even smaller solar influence than scientists thought let’s say a decade ago. AR5 said that in terms of radiative forcing since 1750 the influence of the sun is almost negligible.

Meanwhile solar activity has dropped to levels last seen a century ago. Some scientists suggest the sun might go into a new Maunder Minimum in the coming decades. What influence will that have on our climate?

So the timing of this dialogue is apt. We have a record number of participants, namely five. Two of them – Nicola Scafetta (USA) and Jan-Erik Solheim (NOR) – believe in a large role of the sun. Mike Lockwood (GBR) – in line with AR5 – thinks the sun is only a minor player. The two other participants – Ilya Usoskin (FIN) and José Vaquero (ESP) – seem somewhere in between.

In our Introduction we asked the participants the following questions:

1) What is according to you the “best” solar reconstruction since 1600 (or even 1000) in terms of Total Solar Irradiance?

2) Was there a Grand Solar Maximum in the 20th century?

3) What is your preferred temperature reconstruction for the same period? How much colder was the Little Ice Age than the current warm period?

4) What is the evidence for a correlation between global temperature and solar activity?

5) How much of the warming since pre-industrial would you attribute to the sun?

6) Is the Total Solar Irradiance (TSI) of the sun all that matters for the Earth’s climate? If not, what amplification processes are important and what is the evidence these play a role?

7) what is the sun likely going to do in the next few decades and what influence will it have on the climate? Is there consensus on the predictability of solar variability?

There will be a lot of area to cover. Please head over to the dialogue and feel free to leave a public comment. Keep in mind that the goal of Climate Dialogues is to find out on what participants agree, on what they disagree and why they disagree.



Interview bij Weg met MVO

Ik was enigszins verrast toen ik enkele maanden geleden benaderd werd door de journalisten Ruben Koerhuis en Petra Pronk van de website Weg met MVO. Zij wilden mij interviewen. Een blik op hun site laat zien dat tot nu toe vooral bekende namen uit de Trouw Duurzame 100 zijn geïnterviewd, zoals Marjan Minnesma, Jan Rotmans, Jan Peter Balkenende, Sylvia Borren (van Greenpeace). Maar ook Niek Jan van Kesteren (directeur VNO-NCW) en Wiebe Draijer van de SER.

De titel van hun site is verwarrend. Zij bedoelen ermee dat Maatschappelijk Verantwoord Ondernemen zo vanzelfsprekend wordt dat de term overbodig wordt. Vandaar het “weg met”. MVO gaat om meer dan alleen CO2 uiteraard maar uit de andere interviews blijkt dat CO2 wel een belangrijke rol speelt op dit moment. Zij gaven aan dat ze ook andere visies wilden laten horen en ik stemde derhalve in met het interview. De opnames waren tamelijk imponerend, met vier, vijf camera’s om me heen in een geblindeerde ruimte.

Hopelijk kan het interview bijdragen aan het maatschappelijk debat over klimaat, energie en MVO. Ik dank Petra en Ruben voor de tijd en moeite die ze erin gestoken hebben.


Tol: ‘Opwarming van de aarde is geen catastrofe’

In Elsevier van deze week een uitgebreid interview met Richard Tol. De kop boven het artikel is dezelfde als die boven dit bericht. Het hele interview is de moeite waard. Ik pik er een paar citaten uit:

Volgens de samenvatting voor beleidsmakers van het IPCC is klimaatopwarming een catastrofe. Volgens u niet? Richard Tol: ‘Nee, het is zeker geen catastrofe. De aarde warmt wel op door stijgende uitstoot van broeikasgas CO2, maar het wetenschappelijk onderzoek naar de gevolgen ervan laat zien dat ze over het algemeen beheersbaar zijn. Al moeten we natuurlijk wel blijven opletten. (…)”

Over de stagnatie van de wereldwijde opwarming zegt Tol:

ELSEVIER Is het zo dat de temperatuur al achttien jaar niet stijgt? Tol: ‘Ja, in september kan ik tegen eerstejaarsstudenten zeggen dat de aarde sinds hun geboorte niets warmer is geworden. Vraag is hoe dat kan: niemand heeft het zien aankomen. Vaststaat wel dat de aarde opwarmt door uitstoot van CO2 en andere gassen, en dat de mens hieraan een bijdrage heeft geleverd.

‘Misschien is de invloed van de mens kleiner dan tot nu werd aangenomen, of die van de zon groter. Of de natuurlijke variatie in het klimaat is groter dan gedacht. Misschien warmt de aarde straks dubbel zo snel op. We hebben geen idee. Het is wel ongelukkig: het wordt zo heel moeilijk mensen te overtuigen dat klimaatverandering echt bestaat.’

Over klimaatbeleid in Nederland en het VK:

ELSEVIER Ziet u zichzelf als een pleitbezorger van klimaatbeleid? Tol: ‘Ik zie mezelf niet als activist in welke richting dan ook. Hooguit kan ik me weleens opwinden over de gebrekkige kwaliteit van het klimaatbeleid dat in Nederland of hier in het Verenigd Koninkrijk wordt gevoerd. Het kan veel efficiënter.’ ELSEVIER Hoe? Tol: ‘Het klimaatbeleid dat hier wordt gevoerd, kost heel veel geld, maar levert weinig op. Het heeft eigenlijk niets te maken met klimaat en alles met windmolens. Die windmolens creëren nauwelijks lagere CO2-uitstoot, maar wel veel oppositie tegen klimaatbeleid. Ze zijn lelijk. ’ ELSEVIER Nederland wil in 2050 klimaatneutraal zijn. Is dat haalbaar, denkt u? Tol: ‘Nee. Er zijn simpelweg geen goede oplossingen om de uitstoot in verkeer en landbouw terug te brengen. Je kunt automobilisten wel meer biodiesel en ethanol laten tanken, maar het is onderhand duidelijk dat die niet echt broeikasemissies reduceren.

Lees het hele interview in Elsevier of via Blendle. Het interview is overigens niet geschreven door Simon Rozendaal maar door economieredacteur Michiel Dijkstra.





The Bengtsson Affair and the Global Warming Policy Foundation

Guest post by David Henderson, GWPF

Prologue: a resignation under duress

On 24 April 2014 I sent an email to an eminent meteorologist, Professor Lennart Bengtsson,[1] inviting him to become a member of the Academic Advisory Council of the Global Warming Policy Foundation (GWPF), and three days later I was happy to receive a letter of acceptance; I duly added Bengtsson’s name to our list of Council members, and his acceptance was announced on the GWPF website.

On 1 May the Dutch journalist Marcel Crok published on his blog an interview with Bengtsson. He began by posing the question:Why did you join the GWPF Academic Council? Bengtsson’s response was as follows:

I know some of the scientists in GWPF and they have made fine contributions to science. I also respect individuals that speak their mind as they consider scientific truth (to that extent we can determine it) more important than to be politically correct. I believe it is important to express different views in an area that is potentially so important and complex and still insufficiently known as climate change.

Crok’s final question was:

Are you satisfied with the role that the GWPF has played so far? What could or should they do differently in order to play a more successful and/or constructive role in the discussions about climate and energy?

To which Bengtsson responded:

My impression is that this is a very respectable and honest organisation but I will be happy to reply to your question more in depth when I have got experience of it.

Much to the regret of me and my GWPF colleagues, Bengtsson decided, only two weeks later, to withdraw his acceptance of my invitation. In the letter of resignation that he sent to me, he referred to ‘enormous world-wide pressure put at me from a community that I have been close to all my active life’; and in a letter to colleagues, announcing his decision, he likewise alluded to ‘massive objections from colleagues around the world’.

Though only a few of these ‘massive objections’ have come my way, they presumably have a common theme. The critics typically hold that the GWPF is not a reputable organisation; that the favourable impressions of it which Bengtsson had formed, as voiced in his interview with Crok, were badly mistaken; and that for any professional person to accept to have links with it would be evidence, at best of serious misjudgement, and at worst of a lack of integrity. Hence the Bengtsson affair, and the resulting publicity, have focused attention on the role and work of the Foundation.

As one who has been closely associated with the GWPF from the outset, as chairman of the Council that Bengtsson was invited to join, I offer here a brief personal perspective on the issues thus raised, chiefly with a view to providing information. In doing so, I point to what I see as misconceptions by various commentators, both friendly and hostile. I focus first and chiefly on the work of the Council, but afterwards touch on the work and role of the Foundation as a whole. Lees verder…


Interview Matt Ridley bij FD Energie Pro

Het FD heeft een nieuw online product opgezet, FD Energie Pro. De site is net online gegaan en vooralsnog is de content gratis te lezen. Karel Beckman van de Energy Post heeft als interim hoofdredacteur de eerste verhalen uitgezet. Hij vroeg mij of ik er als freelancer voor wilde schrijven en het toeval wilde dat ik een dag later Matt Ridley zou opzoeken op diens landgoed ten noorden van Newcastle. Beckman wilde graag een interview met hem en zodoende staat dit interview nu als een van de eerste verhalen online. Het verhaal is nu nog gratis integraal te lezen. Hier de intro:

Viscount Matt Ridley is politicus, auteur, journalist, klimaatcriticus, bioloog, natuurliefhebber, ex-bankier, en eigenaar van een steenkolenmijn. Maar hij is bovenal: rationeel optimist. Hij gelooft dat de mensheid dankzij steeds verdere specialisatie en handel een welvarende toekomst tegemoet kan zien. Daarbij is een efficënte energievoorziening onmisbaar – en die kan volgens Ridley niet komen van bronnen als windenergie en biomassa. Journalist Marcel Crok bezocht Matt Ridley op zijn landgoed in Noord-Engeland.



Bengtsson: “Ik voel me bijna een vrijheidsstrijder”

Lennart Bengtsson blijft de gemoederen bezig houden. Ik stuurde hem na zijn besluit uit de GWPF te stappen een lijst met tien vragen. Lastige vragen vermoedelijk want ik vind dat hij met meer details naar buiten zou moeten treden over de e-mails die hij ontving. Hoe dan ook, geen antwoord meer van Bengtsson, die eerder steeds heel snel antwoordde op e-mails. Op twitter gisteren werd gesuggereerd dat hij tijd nodig heeft. Ik vraag me af of dat de reden is van het niet reageren want dit weekend verscheen wel een uitgebreide reactie van zijn hand op een Zweedse website. Hans Labohm woonde een tijdlang in Stockholm en spreekt goed Zweeds en heeft het artikel vertaald. Dank Hans.

Paul Matthews heeft ook een helder overzicht gemaakt van de gebeurtenissen. De reactie van Judith Curry mag je zeker niet missen. Die wijst terecht op de hypocrisie in de klimaatgemeenschap. Van Greenpeace en WWF-medewerkers wordt het geaccepteerd dat ze lead author worden bij het IPCC, maar als een door de wol geverfde wetenschapper een onbetaalde adviesrol gaat vervullen bij de GWPF dan is de wereld te klein.

Hier het integrale stuk van Bengtsson:

Enige overpeinzingen over het klimaat en onze mogelijke toekomst

Op het blog van ‘Stockholms Initiativet’ schreef Lennart Bengtsson een ‘posting’ getiteld: ‘Några tankar om klimatet och vår möjliga framtid’. De vertaling daarvan volgt hier.

 Zo, en geloof je nu in opwarming?

Zoals de meeste vaste bezoekers van dit blog zullen weten – maar nauwelijks degenen die zijn aangewezen op de reguliere Zweedse media – is er rond mij onlangs grote commotie ontstaan. Ik zal hier geen overzicht geven van de media–aandacht die dat heeft gekregen, maar in plaats daarvan proberen om mijn gedachten en handelingen in een breder perspectief te beschrijven.

Ik kan alleen maar zeggen dat ik enorme steun van collega’s, academici en het grote publiek in het Verenigd Koninkrijk, de VS en Duitsland heb gekregen. Ik voel me bijna een vrijheidsstrijder. Ik heb echter geen overdreven illusies want ik ken de macht van het establishment. Het is in ieder geval verheugend om kennis te maken met de liberale en open traditie van de Engels media. De Zweedse media lijken nog te verkeren in de tweede helft van de 19e eeuw, een situatie die we die kennen uit Strindberg’s ‘Röda rummet’ (De rode kamer). Lees verder…


When non-news becomes news

Today many people are surprised that The Times turned non-news into news by putting it on their frontpage: the fact that a paper by Lennart Bengtsson was rejected by Environmental Research Letters. Rejections of papers happens hundreds of times a day, so why put it on the frontpage? Well, the answer is simple, because it fits into a larger “story”. The larger story of course is that Bengtsson accused the climate science community of McCarthyism.

Bengtsson himself is feeding this larger story by saying in the article:

Lennart Bengtsson, a research fellow at the University of Reading and one of the authors of the study, said he suspected that intolerance of dissenting views on climate science was preventing his paper from being published. “The problem we now have in the climate community is that some scientists are mixing up their scientific role with that of a climate activist,” he added.

Non-news becoming news happens all the time in the media, this is how they work. When they smell there is an “affair”, tiny things suddenly get promoted to the frontpage. This happened after climategate as well. Suddenly it was news that AR4 wrongly claimed that Himalayan glaciers would be gone in 2035. I am convinced that without climategate all these other IPCC “gates” wouldn’t have been picked up by the media.

The Dutch journalist Tomas Vanheste was surprised how good this worked. He discovered a minor error in the WGII AR4 report – about the part of The Netherlands that is lying below the sea level. But after Himalaya gate this was suddenly enough to have a sea level gate. It’s all hyperbole but climate “activists” use this in their favor most of the days when the media is eager to exaggerate their latest findings:

It’s All Over: Melting of Western Antarctic Ice Sheet Unstoppable, NASA Says. Read more at http://indiancountrytodaymedianetwork.com/2014/05/14/its-all-over-melting-western-antarctic-ice-sheet-unstoppable-nasa-says-154868


This time IOP, the publisher of ERL replied quickly and complained about the non-news becoming news:

“With current debate around the dangers of providing a false sense of ‘balance’ on a topic as societally important as climate change, we’re quite astonished that The Times has taken the decision to put such a non-story on its front page.

I wish publishers and/or scientists were always so keen to correct decisions of the media, e.g. in case scientific claims are exaggerated.

Anyway, we now know a little more about the rejected paper of Bengtsson and four colleagues because IOP released one of the negative referee reports. This shows that the paper has a lot of similarities with the Lewis/Crok report. The reviewer starts with this:

The manuscript uses a simple energy budget equation (as employed e.g. by Gregory et al 2004, 2008, Otto et al 2013) to test the consistency between three recent “assessments” of radiative forcing and climate sensitivity (not really equilibrium climate sensitivity in the case of observational studies).
The study finds significant differences between the three assessments and also finds that the independent assessments of forcing and climate sensitivity within AR5 are not consistent if one assumes the simple energy balance model to be a perfect description of reality.

In our report we also describe the energy budget method. We actually favor it and claim it currently gives the best indication of the climate sensitivity of the current climate. Nic Lewis now defends this position in the Climate Dialogue that the Dutch institutes PBL, KNMI and myself have set up about this topic.

Lewis and I were criticised for publishing our report at GWPF instead of in a peer reviewed journal. Lewis has published in peer reviewed journals (and even I have one publication) and will do so again so we are not against that. We were and are convinced though that such a long analysis of parts of an IPCC report is not regarded as new science and will therefore be rejected. The referee report of the Bengtsson paper also suggests this:

The overall innovation of the manuscript is very low, as the calculations made to compare the three studies are already available within each of the sources, most directly in Otto et al.

So one may conclude that we see here peer reviewed evidence that our report wasn’t fit for a peer reviewed journal as well.

The referee report contains some awful language that reminds us of the let’s not give fodder to the skeptics remarks in some climategate emails:

Summarising, the simplistic comparison of ranges from AR4, AR5, and Otto et al, combined with the statement they they are inconsistent is less then helpful, actually it is harmful as it opens the door for oversimplified claims of “errors” and worse from the climate sceptics media side.

These kind of motivations should have no place in a reviewer’s report and if I were the reviewer I would have been unhappy to make my report public like IOP now did.

Steve McIntyre has some interesting observations about the reviewer’s report as well noting that the main shortcoming/error of the paper seems to be the fact that it compared observations with models where “no consistency was to be expected in the first place”. McIntyre:

Thus, the “error” (according to the publisher) seems to be nothing more than Bengtsson’s expectation that models be consistent with observations. Surely, even in climate science, this expectation cannot be seriously described as an “error”.



Groene kwesties over De Twijfelbrigade

Mijn eerste reactie op het boek en vooral de boekpresentatie van De Twijfelbrigade is in verkorte versie overgenomen door de website Groene Kwesties. Met de oprichter van deze site, Marco Ploeger, heb ik onlangs geluncht. We kwamen erachter dat we elkaar al kenden van een interdisciplinair vak bij milieukunde van de UvA.

Ik ben overigens nog niet erg opgeschoten in De Twijfelbrigade. Alle energie en aandacht gaat momenteel naar de actualiteit, de Bengtsson-affaire en Climate Dialogue.




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