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.


Bengtsson resigns from the GWPF

Lennart Bengtsson this morning sent an email to Benny Peiser and David Henderson of the GWPF and cc to Hans von Storch and myself amongst others in which he announces his resignation from the GWPF. Bengtsson gave Von Storch permission to post the email on Klimazwiebel so apparently the content is no longer confidential. I think it would have been much more professional if there was first an official announcement from the GWPF, but this is as it is now. So here is the email:

Dear Professor Henderson,
I have  been put under such an enormous group pressure in recent days from all over the world that  has become virtually unbearable to me. If this is going to continue I will be unable to conduct my normal work and will even start to worry about my health and safety.
I see therefore no other way out therefore  than resigning from GWPF. I had not expecting such an enormous world-wide pressure put at me from a community that I have been close to all my active life.  Colleagues are withdrawing their support, other colleagues are withdrawing from joint authorship etc. I see no limit and end to what will happen. It is a situation that reminds me about the time of McCarthy.
I would never have expecting anything similar in such an original peaceful community as meteorology. Apparently it has been transformed in recent years.
Under these situation I will be unable to contribute positively to the work of GWPF and consequently therefore I believe it is the best for me to reverse my decision to join  its Board at the earliest possible time.With my

best regards,
Lennart Bengtsson

This is a very unfortunate development. Bengtsson joined the Academic Advisory Council of the GWPF only two weeks ago. Now one wonders what the crimes of the GWPF are? What makes the GWPF so “bad” that Bengtsson is now regarded as so contaminated that co-authoring a paper with him is not acceptable anymore?

I hope Bengtsson will give much more details in the coming days to weeks about what happened exactly. What does he mean for example when he writes “Colleagues are withdrawing their support”?

This is very bad for the trustworthiness of climate science. Over and over again we as a society are told there is a consensus about CO2 and climate, that there is a large majority in the field etc. However what does that all mean if eminent scientists like Bengtsson are punished severely, only for the fact that he joined an advisory board? Why would one trust climate science if such enormous social pressure is going on?


GWPF statement here

Steve McIntyre responds here

Anthony Watts was about to cross post the 1990 interview I posted yesterday. He now did so together with the news about the resignation.

Support letter from David Gee.

Ben Webster in The Times with a reaction from Bengtsson.

Judith Curry’s reaction. Her first comments:

I will have much more to write about this in a few days.  For now, I will say that I deeply regret that any scientist, particularly such a distinguished scientist as Bengtsson, has had to put up with these attacks.  This past week, we have seen numerous important and enlightening statements made by Bengtsson about the state of climate science and policy, and science and society is richer for this.  We have also seen a disgraceful display of Climate McCarthyism by climate scientists, which has the potential to do as much harm to climate science as did the Climategate emails.  And we have seen the GWPF handle this situation with maturity and dignity.




Bengtsson in 1990: “one cannot oversell the greenhouse effect”

Lennart Bengtsson recently joined the Academic Council of the GWPF. This generated quite some attention on blogs and in the media. I interviewed him, but also Hans von Storch on Klimazwiebel, Axel Bojanowski had a story in Der Spiegel (English version), and there was an article in the Basler Zeitung.

Bengtsson emphasized that he has always been a “sceptic”. In the interview with me he said:

I have always been sort of a climate sceptic. I do not consider this in any way as negative but in fact as a natural attitude for a scientist. I have never been overly worried to express my opinion and have not really changed my opinion or attitude to science.

We all know that in climate discussions climate scientists are quick to say “we are all sceptics” so such a remark says little about Bengtsson’s exact viewpoints. The renowned Dutch science writer Simon Rozendaal then sent me a copy of his interview with Bengtsson published on 27 October 1990 (!) in the Dutch weekly Elsevier (for which Rozendaal still works as a science writer).

We can now confirm that Bengtsson was pretty “sceptic” in 1990. Here is the full translated Elsevier article:

A cool blanket of clouds

Climate expert Bengtsson puts the threat of the greenhouse effect in perspective

Next week, a large conference on the global climate will be held in Geneva. The most important topic of discussion: the greenhouse effect. Many hold the opinion that our planet is warming by the increase in carbon dioxide and that a climate disaster is looming. Maybe so, says Lennart Bengtsson, Europe’s most important climate scientist. Or maybe not. Bengtsson doesn’t actually know for sure. It could go either way.

Lennart Bengtsson is so far not daunted by the looming climate disaster. He frowns when looking at the tierische Ernst with which the rest of the world embraces the prediction that the planet warms due to the increase in gases like carbon dioxide (CO2). ‘It would become serious if the atmospheric CO2 concentration would decrease. Thanks to the greenhouse effect Earth is a habitable place. Were its concentration to decrease, then mean temperatures would plummet far below freezing. That really would be a catastrophe.’

The Sweed, who appears and talks like Max von Sydow, is director of the European Center for Medium Range Weather Forecast in Reading (United Kingdom), which supports eighteen European national weather centers like Dutch KNMI with computer models and simulations. Soon he will become director of the Max Planck institute in Hamburg and thereby will be in charge of Europe’s most important greenhouse effect computer model. ‘Until now the greenhouse effect research has concentrated in the United States, but Europe is advancing.’

There is something strange about the greenhouse effect. Many scientists babble and publish about it, but few really understand its ins and outs. Most of them treat assumptions as were they facts. Suppose that it would become two degrees warmer, how much higher would the Dutch dikes have to become? Or: suppose that we want to reduce CO2 emissions and still maintain economic growth for not so strong economies of Poland, Greece, and China, how much would the emissions of the wealthy Netherlands have to decrease? For the question whether the underlying assumptions are actually correct, one has to ask climate experts like Bengtsson.

He emphasizes that the greenhouse excitement is founded in computer simulations. And that computer generated models are not complete nonsense. ‘If for example such a model starts with a globally uniform temperature, then within a few months of simulation one would start to see the tropics warming and polar regions cooling. Remove the Amazon and after some time it reappears due to the torrential tropical rains. Such general characteristics of the global climate are part of the models.’

However, the models provide insufficient insight. ‘They are too coarse. While weather predictions nowadays have grid sizes of 100 by 100 kilometer, climate models work on a 500 by 500 km grid. In addition, models have problems with clouds. They are not able to predict what effect clouds have and they cannot distinguish between high and low clouds, yet we know that this differentiation has important consequences.’ Many other important aspects are lacking. Some of those cannot be incorporated simply because they are not well understood. ‘For a large part of the emitted carbon dioxide we do not know where it stays.’


Would there be no clouds, everything would be simple. ‘With a clear sky, increasing carbon dioxide or methane would lead to a reduction of heat radiation from the earth to the atmosphere. In addition, water vapor would amplify the so-called greenhouse effect. If temperatures increase, more water evaporates and water vapor is a powerful greenhouse gas.’

However, clouds do exist. It is these fluffy tufts that diminish much of the commotion surrounding the climate disaster. Clouds cool because they reflect sunlight. On the ground we notice this when we’re in a shadow. At the same time clouds warm because they prevent heat radiation from directly escaping to space: ground frost nearly always occurs under cloud free conditions. The simple question as to whether clouds cool or warm the Earth was until recently unanswered, and this says a lot about the current state of meteorology.

Among climate experts the opinion that clouds cool Earth is gaining ground, Bengtsson observes. ‘There are recent satellite observations, as reported in the scientific magazine Nature, showing that clouds reduce the greenhouse effect. In particular low level clouds are efficient cooling agents.’

Theoretically, the greenhouse effect could even cause a cooling rather than a warming of Earth. ‘The cooling effect of clouds is five times as strong as the temperature increase due to a doubling of atmospheric CO2.’ There is even an amplification of this feedback. Bengtsson: ‘If it gets warmer, clouds become whiter and thereby reflect more solar radiation.’

Such feedbacks are hardly part of the computer models that predict the warming, according to Bengtsson. ‘Almost no model is capable of dealing with the behavior of clouds. The models builders claim they do, but when we redo the calculations that turns out not to be true.’

There are other problematic issues. Were climate to really warm, snow and ice would have to melt. That would result in additional warming because white surfaces reflect more sunlight. ‘This additional warming is not present.’ Maybe the largest omission in knowledge about climate are the oceans.’ In most models it is assumed that the ocean is fifty meters deep, which is an average. But there are parts of the oceans that are several kilometers deep. Those would slow any potential warming. You could hide thousand years of warming in the ocean.’

The one small meteorological detail from the enormous amount of uncertainties, ambiguities and question marks that has become better understood is that an increase of CO2 and some other gases potentially has a warming effect. And that is what politics is focusing on right now. Bengtsson: ‘What happens in the Atlantic Ocean could have bigger consequences, but nevertheless all attention is focusing on the greenhouse effect.’


Bengtsson believes that climate experts should not pretend to be more knowledgeable than they really are. ‘In case of the greenhouse effect there is an interaction between media, politics and science. Every group pushes the other groups. Science is under pressure because everyone wants our advice. However, we cannot give the impression that a catastrophe is imminent. The greenhouse effect is a problem that is here to stay for hundreds of years. Climate experts should have the courage to state that we are not yet sure. What is wrong with making that statement clear and loudly?’

The excitement of the last weeks has moved everything into high gear. A United Nations committee (the IPCC) has released a report at the end of August which suggests that there is a broad scientific consensus about the existence of the greenhouse effect. This already has had political ramifications in many countries. For example, halfway October hundreds of Dutch politicians, experts, civil servants and industrialists have been discussing in Rotterdam themes from the 1960s like whether and how the Netherlands could lead the way (again). And early November there will be a global conference in Geneva about the global climate.

Bengtsson thinks that the IPCC has been particularly actuated for political reasons. ‘The IPCC prediction that with a doubling of CO2 in the atmosphere the temperature on Earth would rise by two degrees should be taken with a grain of salt.’

Due to the lack of understanding a thermometer remains crucial. And it is not pointing in the direction of a doomsday. ‘The temperature over the Northern Hemisphere has decreased since about 1950. In some countries the eighties were very warm, but there are countries where this is not the case. On Greenland there is little to be seen of the greenhouse effect. It has been very cold during the last couple of years.’

‘If you talk to the greenhouse mafia about these observations, they provide some answers, but those are not real. There is no proper support for the claim that the greenhouse effect should already be visible. It is sometimes stated that the Southern Hemisphere is warming. But there are so few observational sites over there that it is very difficult to draw any definitive conclusions about the temperature in the Southern Hemisphere.’

Bengtsson is not the only climate expert who thinks that much of the excitement about the greenhouse effect is undue. Many of his colleagues have been rather uneasy about what happened after they opened Pandora’s box. They have become afraid, now that politicians, camera crews, pressure groups and environmental departments worldwide have thrown themselves at the climate disaster, to openly state that what they have declared may have been a bit premature.

Bengtsson: ‘Many of us feel rather uncomfortable with much of what has been claimed about the greenhouse effect. No one had been talking about it because temperatures had been slightly on the decline during the last 30 years. Only after Jim Hansen of NASA had put the issue back on the agenda after the warm summer of 1988 has it become part of the political agenda. In itself there is no problem with that. Looking hundreds of years ahead the greenhouse effect could become a serious problem. Some policies are obviously a clever thing to do: save energy, become less dependent on oil, those are good ideas. But one cannot oversell the greenhouse effect. There are many environmental problems that are much more urgent like that of the sulphur dioxide in Eastern Europe.’


New Climate Dialogue about climate sensitivity

Today – after a long pause – a new Climate Dialogue has started about climate sensitivity and transient climate response. This of course is a highly relevant topic. Equilibrium climate sensitivity (ECS) and especially the transient climate response (TCR) largely determine how much warming we can expect this century.

Climate Dialogue is a platform for discussions between invited climate scientists on controversial climate topics. They represent a range of views. Discussions are strictly moderated and should be on topic. Last year we did four Climate Dialogues, about arctic sea ice, long-term persistence, regional climate models and the hot spot in the tropics.

We are very happy that a few key players in the debates surrounding climate sensitivity have agreed to participate in this Climate Dialogue. John Fasullo of NCAR is well-known for his publications with Kevin Trenberth about the role of the natural variability and the oceans in the recent hiatus. James Annan, who recently moved back to the UK after working for many years in Japan, has also published a lot about climate sensitivity and is also frequently blogging about it. Finally Nic Lewis is a relative newcomer in climate science. After a career in the financial sector he recently became a climate scientist, focusing on climate sensitivity. He published a few papers about climate sensitivity, one with a group of IPCC lead authors.

A Sensitive Matter
Some readers will remember that Nic Lewis and I published a GWPF report in March of this year with the title A Sensitive Matter: How the IPCC hid the good news on global warming. One of the main conclusions of our report was that observationally based estimates for ECS and TCR (based on the so-called instrumental period, say 1850-2014) are “superior” at the moment and are to be preferred over estimates from GCMs or paleorecords.

We claim that these “observational” estimates indicate best estimates for ECS that are close to the lower boundary of the likely range in several IPCC reports which is 1.5–4.5°C. We give an “observational” likely range of 1.25-3°C with a best estimate of 1.75°C. This is substantially lower than the average ECS value of the CMIP5 models which is more than 3°C.

IPCC gave a best estimate of 3°C in AR4 but none in AR5. This lack of a best estimate was only mentioned in a footnote in the SPM. Lewis and I wrote in our report that the discrepancy between the observationally based best estimate and the model based best estimate was likely the main reason why IPCC didn’t give a best estimate this time. So IPCC on the one hand says climate sensitivity will likely be anywhere between 1.5–4.5°C and no best value can be given. But when doing projecetions AR5 relies (also in the Working Group II and III reports) on climate models that have an average climate sensitivity of 3.2°C.

So it is really important to find out where the discrepancy between the observationally based and model based estimates comes from. This will certainly be a crucial question in this Climate Dialogue.

Lewis in his guest blog repeated his likely range for ECS being lower than that of AR5:

The soundest observational evidence seems to point to a best estimate for ECS of about 1.7°C, with a ‘likely’ (17-83%) range of circa 1.2–3.0°C.

Annan agrees that the observational record points towards lower values for ECS and TCR. But nevertheless he comes up with slightly larger value for the best estimate than Lewis:

The recent transient warming (combined with ocean heat uptake and our knowledge of climate forcings) points towards a “moderate” value for the equilibrium sensitivity, and this is consistent with what we know from other analyses. Overall, I would find it hard to put a best estimate outside the range of 2-3°C.

Fasullo did not yet give his preferred likely range but he emphasized in his guest blog that lowering the lower boundary of the likely range in AR5 to 1.5°C (was 2°C in AR4) maybe was justified at the time but not any longer:

In short, I argue that although IPCC’s conservative and inclusive nature may have justified such a reduction at the time of their report, the evidence accumulated in recent years argues increasingly against such a change. Lees verder…


Elsevier (1990): Bengtsson relativeert dreiging van broeikaseffect

[Update: Met dank aan Simon Rozendaal is hier nu ook het volledige interview met Bengtsson destijd in Elsevier]

De beslissing van Lennart Bengtsson om toe te treden tot de Academic council van de GWPF heeft behoorlijk wat aandacht getrokken. Na mijn eigen interview met hem volgden interviews met Hans von Storch, Axel Bojanowski in Der Spiegel en een verhaal in de Basler Zeitung. Wat opvalt is dat Bengtsson telkens benadrukt dat hij altijd “sceptisch” is geweest.

In zijn interview met mij schreef Bengtsson:

I have always been sort of a climate sceptic. I do not consider this in any way as negative but in fact as a natural attitude for a scientist. I have never been overly worried to express my opinion and have not really changed my opinion or attitude to science.

Nu zegt dat op zichzelf weinig. In debatten tussen sceptici en mainstreamers zeggen mainstreamers ook geregeld dat “alle wetenschappers sceptisch zijn” en het zegt dus op zichzelf weinig over hoe mainstream dan wel sceptisch Bengtsson feitelijk is.

Simon Rozendaal van Elsevier stuurde me een e-mail met citaten van Bengtsson waaruit blijkt dat Bengtsson inderdaad al heel vroeg in het klimaatdebat openlijk zeer kritisch was over de dreiging van het broeikaseffect. Uit de e-mail van Rozendaal:

Ik publiceerde op 27 oktober 1990 (!), toen hij al directeur was van het centrum in Hamburg, een interview met hem in Elsevier. De kop: Een koele deken van wolken. Onderkop: Klimaatdeskundige Bengtsson relativeert dreiging van broeikaseffect.

In het interview benadrukt Bengtsson o.a. de onvolledigheid en grofmazigheid van de computermodellen waarop de broeikascommotie is gebaseerd en dat we veel te weinig van wolken begrijpen.

Wat citaten:

‘Er is bij het broeikaseffect een wisselwerking tussen de media, de politiek en de wetenschap. Elke partij vuurt de andere aan. De wetenschap staat onder druk, omdat iedereen een advies van ons wil. Wij mogen echter niet de indruk wekken dat de catastrofe aanstaande is. Het broeikaseffect is een probleem dat nog honderden jaren onder ons zal zijn. De klimaatdeskundigen moeten de moed hebben om te zeggen dat we het nog niet zeker weten. Wat is er verkeerd aan dat luid en duidelijk te zeggen?’

‘Er is geen enkele steun voor de claim dat het broeikaseffect al merkbaar zou zijn. Men zegt dan dat het zuidelijk halfrond al opwarmt. Daar zijn echter maar zo weinig observatieposten dat er over de temperatuur daar hoegenaamd niets zinnigs te zeggen is.’

‘Velen van ons voelen zich uiterst ongemakkelijk met wat er allemaal over het broeikaseffect wordt beweerd. Het is al dertig jaar bekend. Niemand had het er over omdat de temperatuur de afgelopen dertig jaar lichtelijk is gedaald. Pas nadat in de warme zomer van 1988 Jim Hansen van de Nasa het onderwerp weer oppikte, is het op de politieke agenda gekomen. Daar is niets op tegen. Als je een paar honderd jaar vooruit kijkt zou het broeikaseffect best een ernstig probleem kunnen worden. Sommige maatregelen zijn ronduit verstandig: energie besparen en minder afhankelijk worden van olie, dat zijn goede zaken. Maar men mag het broeikaseffect niet oversellen. Er zijn talloze vervuilingsproblemen die urgenter zijn, zoals het probleem van de zwaveldioxide in Oost-Europa.’

Wow! Wat mij het meest frappeert aan de uitspraken is dat ze anno 2014 nog steeds opgaan. Wolken zijn nog steeds onbegrepen, de grofmazigheid van modellen is nog altijd een issue. “Als je een paar honderd jaar vooruit kijkt zou het broeikaseffect best een ernstig probleem kunnen worden.” Ook die opmerking kun je nog steeds prima maken. De citaten laten helaas ook zien hoe bedroevend weinig vooruitgang er is geboekt in het wetenschappelijke klimaatdebat.

Rozendaal voegde er nog dit aan toe:

De wereld is niet zwart of wit (scepticus of alarmist), er zijn op zijn minst vijftig tinten grijs.



Lennart Bengtsson: “The whole concept behind IPCC is basically wrong”

The GWPF yesterday announced that Swedish scientist Lennart Bengtsson joins their Academic Advisory Council. Among the members of this council are many well-known “climate sceptics” like Richard Lindzen, Ross McKitrick, Henrik Svensmark, Bob Carter, Nir Shaviv etc.

Bengtsson (born 1935) was the director of of ECMWF (European Centre for Medium-Range Weather Forecasting) for 18 years and after that he was the director of the Max Planck Institute for Meteorology in Hamburg. So his background is very “mainstream”. His entry to the GWPF Council will certainly have raised a few eyebrows in the climate community that sees the GWPF as a sceptical think tank.

Bengtsson has written some very nuanced/critical opinion articles in recent years (see here and here). I decided today to ask Bengtsson about his motivation to join the GWPF Council and sent him a list of questions to which he kindly responded.

Why did you join the GWPF Academic Council?
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.
My interest in climate science is strictly scientific and I very much regret the politicisation that has taken place in climate research. I believe most serious scientists are sceptics and are frustrated that we are not able to properly validate climate change simulations. I have always tried to follow the philosophy of Karl Popper. I also believe that most scientists are potentially worried because of the long residence time of many greenhouse gases in the atmosphere. However, our worries must be put into a context as there are endless matters to worry about, practically all of them impossible to predict. Just move yourself backward in time exactly 100 years and try to foresee the evolution in the world for the following 100 years.

Is this your way of telling the world that you have become a “climate sceptic”? (many people might interpret it that way) If not, how would you position yourself in the global warming debate?
I have always been sort of a climate sceptic. I do not consider this in any way as negative but in fact as a natural attitude for a scientist. I have never been overly worried to express my opinion and have not really changed my opinion or attitude to science. I have always been driven by curiosity but will of course always try to see that science is useful for society. This is the reason that I have devoted so much of my carrier to improve weather prediction.

Is there according to you a “climate consensus” in the community of climate scientists and if so what is it?
I believe the whole climate consensus debate is silly. There is not a single well educated scientist that question that greenhouse gases do affect climate. However, this is not the issue but rather how much and how fast. Here there is no consensus as you can see from the IPCC report where climate sensitivity varies with a factor of three! Based on observational data climate sensitivity is clearly rather small and much smaller that the majority of models. Here I intend to stick to Karl Popper in highlighting the need for proper validation.

Mojib Latif once said at a conference of the WMO (in 2009) “we have to ask the nasty questions ourselves”. Do you think the climate community is doing that (enough)? or are others like the GWPF needed to ask these “nasty” questions? If so, what does this say about the state of Academia?
I think the climate community shall be more critical and spend more time to understand what they are doing instead of presenting endless and often superficial results and to do this with a critical mind. I do not believe that the IPCC machinery is what is best for science in the long term. We are still in a situation where our knowledge is insufficient and climate models are not good enough. What we need is more basic research freely organized and driven by leading scientists without time pressure to deliver and only deliver when they believe the result is good and solid enough. It is not for scientists to determine what society should do. In order for society to make sensible decisions in complex issues it is essential to have input from different areas and from different individuals. The whole concept behind IPCC is basically wrong.

I noticed that some climate scientists grow more sceptical about global warming after their retirement. Can you confirm this? Does it apply to yourself? Is there a lot of social pressure to follow the climate consensus among working climate scientists which can explain this?
Wisdom perhaps comes with age. I also believe you are becoming more independent and less sensitive to political or group pressure. Such pressure is too high today and many good scientists I believe are suffering. I am presently a lot on my own. As I have replied to such questions before, if I cannot stand my own opinions, life will become completely unbearable.

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?
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.

From the GWPF:
Professor Lennart Bengtsson has a long and distinguished international career in meteorology and climate research. He participated actively in the development of ECMWF (European Centre for Medium-Range Weather Forecasting) where he was Head of Research 1975-1981 and Director 1982-1990. In 1991-2000 he was Director of the Max Planck Institute for Meteorology in Hamburg. Since 2000 he has been professor at the University of Reading and from 2008 the Director of the International Space Science Institute in Bern, Switzerland.

Professor Bengtsson has received many awards including the German Environmental Reward, The Descartes Price by the EU and the IMI price from the World Meteorological Organisation (WMO). He is member of many academies and societies and is honorary member of the American Meteorological Society, the Royal Meteorological Society and European Geophysical Union. His research work covers some 225 publications in the field of meteorology and climatology. In recent years he has been involved with climate and energy policy issues at the Swedish Academy of Sciences.



Twijfels bij De Twijfelbrigade

[Update 30 april]
Mijn keuze voor het citaat van Bengtsson krijgt een opmerkelijk staartje. Zojuist maakt GWPF bekend dat Bengtsson is toegetreden tot de council van de GWPF, waar onder andere ook Lindzen, McKitrick en Tol in zitten. Zie

Verandert dit de situatie? Behoort Bengtsson nu definitief tot de “twijfelbrigade”?

Ik ben benieuwd of de GWPF dan wel Bengtsson met een uitgebreidere toelichting zullen komen. Ik denk dat velen in de klimaatgemeenschap deze beslissing met gefronste wenkbrauwen zullen aanhoren. Wordt ongetwijfeld vervolgd.
[einde update]

Jan Paul van Soest presenteerde gistermiddag in De Balie in Amsterdam zijn boek De Twijfelbrigade. Er was een bijeenkomst van ruim twee uur, ingeleid door Maurits Groen (die het boek heeft uitgegeven) en geleid door Pier Vellinga. Er was een debat waar geen leden van de twijfelbrigade voor waren uitgenodigd. In het panel zaten Monique Riphagen van het Rathenau Instituut, Liset Meddens van Fossil Free NL, socioloog Gert Spaargaren van Wageningen Universiteit, organisatie-adviseur Erik van Praag, onderzoeker en blogger Bart Verheggen en journalist Martijn van Calmthout van de Volkskrant. Hans Labohm en ik waren voor zover ik kon nagaan de enige twee aanwezigen namens de ‘twijfelbrigade’.

Het boek kreeg al voor de lancering de nodige aandacht in de media, een uitgebreid interview in Trouw (waarin Labohm en ik beiden genoemd worden) en gisteren een in de Volkskrant (niet online beschikbaar). Maarten Keulemans schreef op persoonlijke titel een Volkskrant-blogartikel dat heel kritisch van toon is en dat als teneur heeft dat Van Soest als duurzame ondernemer belang heeft bij een alarmistische boodschap. Van Soest was overduidelijk woest over dat artikel en noemde het gisteren een “sardonisch stukje”.

Het boek zelf heb ik vooralsnog alleen maar kunnen scannen. Duidelijk is dat Van Soest een serieuze poging heeft ondernomen om klimaatsceptici in kaart te brengen. Hij scheert ze niet over een kam en onderscheidt wel zes, zeven verschillende typen klimaatsceptici. Daarover later meer als ik het boek gelezen heb.

Ik baseer mijn eerste reacties nu vooral op de interviews in Trouw en de Volkskrant, op de bijeenkomst gisteren en op het voorwoord. Het belangrijkste wat opvalt is dat “de klimaatconsensus” zoals die is vastgesteld door “de Klimaatwetenschap” als een in steen gebeitelde waarheid gezien moet worden. Iedereen die daar nog aan twijfelt behoort tot de twijfelbrigade en die is zoals het woord al zegt alleen maar uit op twijfel zaaien en niet op waarheidsvinding of wetenschappelijk inzicht. Uit het voorwoord:

De klimaatsceptici zijn erin geslaagd de wereld op zijn kop te zetten, door klimaatwetenschap en -wetenschappers in het verdomhoekje te plaatsen, in plaats van wetenschappelijke kennis te accepteren als de beste beschrijving en begrip van de realiteit.

Hier gaat het me even om het tweede vetgedrukte deel. De Klimaatwetenschap (met een hoofdletter K) heeft ons de beste beschrijving en begrip van de realiteit gegeven. Dit is de klimaatconsensus. In het boek zal er hopelijk een enigszins genuanceerde versie van die klimaatconsensus worden gegeven. Gisteren beperkten de heren in het panel zich echter tot een karikatuur van die consensus. Namelijk dat het 5 VWO natuurkunde is en dat iedereen het dus zou moeten kunnen snappen. Vier, vijf maal viel ook de term “het absorptiespectrum van CO2″. Waarmee geïmpliceerd werd dat het toch logisch is dat CO2 voor opwarming zorgt. Door dit op te merken suggereerden de panelleden dat de twijfelbrigade dat soort basiskennis in twijfel trekt. Het overgrote merendeel van de klimaatsceptici doet dat echter niet. Lees verder…


Hoe lang gaat de CO2-opname nog door?

Guido van der Werf van de VU heeft mede naar aanleiding van het Lewis/Crok-rapport een uitgebreid blogbericht geschreven dat vooral kijkt naar naar de scenario’s. Ik verwacht de komende jaren veel aandacht voor de scenario’s. Momenteel zitten de emissies boven het zogenaamde RCP8.5 scenario, het hoogste van de vier IPCC-scenario’s. Een relatief lage klimaatgevoeligheid kan nog altijd aanzienlijk wat opwarming geven als de concentratie aan broeikasgassen in de atmosfeer snel toeneemt.

Onderstaand blogbericht is ook geplaatst op de blog van Bart Verheggen.

Gastblog van Guido van der Werf

Met simpel doortrekken van de ontwikkelingen van de laatste 15 jaar komen we dicht in de buurt van het hoogste IPCC scenario wat CO2-uitstoot betreft, het zogenaamde RCP8.5-scenario.

Onzekerheden in hoeverre het land en oceanen CO2 blijven opnemen zijn belangrijk en vormen een van de grote onzekerheden wat toekomstige klimaatverandering betreft.

Ongeveer een kwart van de forcering van het RCP8.5-scenario zit in niet-CO2 factoren waarin met name methaan een belangrijke rol speelt.

Zelfs als je deze niet-CO2 factoren buiten beschouwing laat kom je met lage waardes van klimaatgevoeligheid rond of boven de 2 graden opwarming in 2100 uit. Het meenemen van deze factoren of hogere klimaatgevoeligheden leveren uiteraard meer opwarming op, en vice versa.

Om toekomstige klimaatverandering te berekenen zijn grofweg vier factoren van belang: klimaatgevoeligheid, de netto klimaatforcering, de benodigde tijd om een nieuw evenwicht te bereiken, en natuurlijke factoren. De klimaatgevoeligheid heeft de laatste weken veel aandacht gekregen, met name vanwege een rapport van Nic Lewis en Marcel Crok waar een lagere klimaatgevoeligheid uit kwam dan de 1.5-4.5 graden opwarming per CO2 verdubbeling van het laatste IPCC rapport.

Dit blogbericht gaat over de klimaatforcering en dan met name over de toekomstige uitstoot en atmosferische concentratie van CO2. Met behulp van acht grafieken laat ik zien wat voor factoren belangrijk zijn en wat de toekomstige CO2-concentratie zou kunnen zijn bij ‘business as usual’, oftewel bij geen mitigatie. Naast CO2 zijn er uiteraard ook andere factoren van belang inclusief emissies van methaan (CH4) en lachgas (N2O) maar die laat ik hier grotendeels buiten beschouwing. Lees verder…


Tol: alarmistisch IPCC is een partij in het debat geworden

Onderstaand opiniestuk van Richard Tol stond afgelopen weekend in NRC.

De vier ruiters van de apocalyps zijn weer gezien. Hongersnood, pestilentie, oorlog, dood. Alles is te vinden in de krantenkoppen over het Vijfde Assessment Rapport (AR5) van Werkgroep II van het Intergouvernmentele Forum voor Klimaatverandering (IPCC).

Het rapport zelf is natuurlijk minder dramatisch. Maar er wordt hier en daar wel wat overdreven, met name in de Samenvatting voor Beleidmakers. Het rapport zegt dat er minder voedsel verbouwt kan worden – maar vergeet technologische vooruitgang in de landbouw: verbeterde gewassen, slimmere bemesting en irrigatie, enzovoort. De landbouwopbrengst zal niet afnemen vanwege klimaatverandering; de toename in de opbrengst zal langzamer gaan.

Gezondheid is een ander voorbeeld. Ongebruikelijk veel mensen sterven als de winter ongewoon koud is of de zomer extra heet. Het effect is groter in de winter, maar het IPCC benadrukt de zomer. Lees verder…




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