Friday, February 26, 2010

Statement by ICSU on the controversy around the 4th IPCC Assessment

This statement is endorsed by the Officers of the International Council for Science (ICSU, February, 2010). ICSU is a non-governmental organization representing a global membership that includes both national scientific bodies (119 members) and international scientific unions (30 members). The statement does not necessarily represent the views of all individual Members. See

As a scientific organization with global representation and active engagement in global environmental change research including climate change, the International Council for Science (ICSU) has been closely following the ongoing controversy concerning the Intergovernmental Panel on Climate Change (IPCC). Important issues have been raised in relation to both the interpretation of scientific knowledge, especially in making predictions of future developments, and the procedures used by the IPCC in its assessment.

With more than 450 lead authors, 800 contributing authors, and 2500 reviewers from more than 130 countries, the IPCC 4th Assessment Report represents the most comprehensive international scientific assessment ever conducted. This assessment reflects the current collective knowledge on the climate system, its evolution to date, and its anticipated future development. It is now apparent, and given the scale of the enterprise not surprising, that some errors did occur in part of the report. However, in proportion to the sheer volume of the research reviewed and analyzed, these lapses of accuracy are minor and they in no way undermine the main conclusions. It should be noted that the errors were initially revealed and made public by scientists and the misinterpretations can now be corrected accordingly. Rather than compromising the integrity and credibility of the science of climate change, this series of events is in itself a demonstration of the vigour and rigour of the scientific process.

In any area of science it is important that errors, or previous assumptions that change in the light of new evidence, are openly admitted and corrected. This is especially the case for the IPCC reports, which have broad and deep implications for societal choices and policy. Lessons should be learnt from the current controversy. The IPCC processes are tried and tested but they are not infallible (and have never been presented as such by the scientific community). In the light of recent events, it is timely to review these processes to see whether modifications can be made that i) reduce the chance of errors being introduced in the first place, and ii) optimise the mechanisms for identifying and correcting errors that do inadvertently remain in the final IPCC reports. The procedures for the IPCC assessments engage not only the scientific community, but also governmental agencies. They are complicated and not always easily understood by those not directly involved. It is important to continue to strive to make these processes as transparent and accountable as possible.

The identified errors in the IPCC report are regrettable but, in the context of the complex IPCC process, understandable. That these errors have resulted in attempts to discredit the main conclusions of the report, accusations of scientific conspiracies, and personal attacks on scientists is unacceptable. Scientific assessments, such as those of the IPCC, are a crucial basis for making the decisions that will shape our society now and in the future. Scientists, governments, and other societal stakeholders need to work together to ensure the quality and relevance of such assessments. We need to learn from the current controversy and make improvements where necessary. We should be grateful to the many thousands of scientists who give freely of their time to contribute to the IPCC and other scientific assessments. And we should continue to be critical but constructively so and in ways that openly recognize the strengths and limitations of the scientific process itself.


itisi69 said...

"With more than 450 lead authors, 800 contributing authors, and 2500 reviewers from more than 130 countries"
Quantity is not always a guarantee for quality...

eduardo said...
This comment has been removed by the author.
eduardo said...

It seems that some governments want to explore possibilities for more in-depth reform of the IPCC

Zajko said...

Interesting how this is painted as the self-correcting process of science and scientists, yet the document admits that the errors were made public (through the mass media) before they were "corrected accordingly".

@ReinerGrundmann said...

How independent will the review of the IPCC be?
Guardian report here

Telegraph report here

Hans Erren said...

The fundamental flawe in the IPCC assesments is that:
1) Unlikely SRES scenarios are forced upon the modellers
2) Lead authors are the referees of the comments. Self citation is dominant in "reviews" and opposing views are neglected.

Hans von Storch said...

Hans/6 - can you quantify in some way your second assertion "Self citation is dominant in "reviews" and opposing views are neglected.", or present a case study with some details? -- Hans

Hans von Storch said...

Zajko/4 - it is also noteworthy that they describe the process of generating errors as "random" - even if it seem not to be so. The known/admitted errors cluster in one Working Group (namely 2), and they were all of dramatizing character. If they would be random, they would pop up also in working Group 1, and some of them would describe the implications as less severe.

P Gosselin said...

"The known/admitted errors cluster in one Working Group (namely 2), and they were all of dramatizing character."

That says a lot about what is done with the science. Okay, sometimes I tend to trash climate science, and admittedly wrongly so at times. There's a lot of good climate science and the problem is that much of it gets filtered and some gets really blown up to grotesque proportions. Obviously, as Prof von Storch seems to imply, there appears to be a trend to suppress or to distort the results of good science. Judith Curry recently alluded to this.

richardtol said...

Silly me.

I wrote that one of the problems of the IPCC is that appointments are made by the Departments of the Environment. Instead, appointments to the IPCC should be made by the national academies, and the IPCC should be placed under the supervision of the ICSU.

That was a bad mistake I made.

Leigh Jackson said...

A few comments.

The IPCC is endorsed by the world's leading National Academies and the ICSU.

The IPCC has admitted that a blunder was made in WG2 regarding Himalyan glacier melt which in no way affects the accuracy of what is found in WG1.

The Dutch government have acknowledged that they gave an incorrect figure relating to risk of flooding in the Netherlands in a report which was quoted in WG2.

Some questions have been raised about the accuracy of statements in WG2 relating to the Amazonian rainforest, African crops and storm risk. The IPCC stands by its statements on these questions.

Do I understand correctly?

itisi69 said...

"The Dutch government have acknowledged that they gave an incorrect figure relating to risk of flooding in the Netherlands in a report which was quoted in WG2."

Could you give me a link were this has been stated? I'm not aware of the fact that the Dutch government has acknowledged that they gave an incorrect figure.

The "Planbureau voor Leefmogeving" gave the correct figures that 26% of the Netherlands is below sea level and 55% is protected by dams, dunes and other protecting means. This is not below sea level, though.
It's not their fault that IPPC is giving the wrong information.

Below the Dutch website where the fault is mentioned, there's NO mentioning of an acknowledgement that they give the incorrect figure.

Hans von Storch said...

itisi69/12 - would you not think that this Netherland-area issue is really one of these silly errors which happen? Or would you assume that somebody constructed this with an intention?
This is very different with the damage/hazard issue (cf., where reviewers pointed to the problem, and the IPCCC decided not to take the critique seriously.
So, I would suggest to deal with the issues, which matter, not with the little stupid errors.

The disaster/hazard-issue is the elephant in the room.

Marco said...

@Itisi69 (and a bit Hans von Storch):

The PBL does not state it gave the IPCC the right information. It actually suggests strongly that the wrong formulation is their fault:
"een fout in een door het Planbureau voor de Leefomgeving geleverde formulering over het overstromingsrisico van Nederland"
"A mistake in the by the Planbureau voor de Leefomgeving submitted formulation about the flooding risks of the Netherlands".

Leigh Jackson said...

Within an hour of my previous post, over lunch, I happened to read this week's edition of New Scientist. They say that the IPCC admitted to them this week that the statement relating to African crop yields "projected reductions in yield in some countries could be as much as 50 per cent by 2020" is an error.

Referring to the effect of climate change on water supply in Africa NS also suggests "... the apparent desire to find a quotable number for droughts in Africa arguably led the IPCC to an unbalanced conclusion" when drawing upon a study by Nigel Arnell of the University of Reading.

The same article states that the Dutch government acknowledged their error earlier this month.

Leigh Jackson said...

Link to the New Scientist article.

richardtol said...

The Dutch error is indeed a tiny mistake.

It would be irrelevant were it not for the facts (1) that the error emerged shortly after the responsible minister of the Netherlands had declared she would tolerate no more errors in the IPCC; and (2) that the error was due to the PBL, the Dutch organisation which delivers most IPCC authors and is now charged with "independently" reviewing the IPCC.

The error is small in substance, but large in politics.

Leigh Jackson said...

The New Scientist article looks very damaging for WG2. We must hear first-hand what the IPCC have to say.

There does appear to be a disturbing synergy between the Himalaya error and the Africa error.

New Scientist describe the commissioned report on by Ali Agoumi as being thin evidence carelessly treated.

One egregious error I was prepared to accept as an aberration. Two such synergistic errors - devasting physical and human impact of climate change in Asia and Africa - is either uncanny or something more serious.

Marco said...

@Leigh Jackson:

Did you real the whole piece? It also contains a criticism in which a conclusion was WATERED DOWN compared to the evidence in the literature.
As John Hart apparently noted:
"Far from the IPCC being guilty of exaggeration [....] its caution may have led it to underplay the extinction holocaust awaiting the planet's biodiversity in the coming century".

Leigh Jackson said...

Marco 19
I read the whole article. On the question of species extinction, I read the New Scientist article as indicating that criticism of the IPCC cuts both ways.

Not so when it comes to the accuracy of the statement by the IPCC on the question of the effect of climate change on crop yields in Africa. If the IPCC are admitting their statement about this was wrong, in the way which New Scientist describes, then this is another serious blunder.

itisi69 said...

Fair enough, apparently I misread the PBL message.

"that the error was due to the PBL, the Dutch organisation which delivers most IPCC authors and is now charged with "independently" reviewing the IPCC."

This makes it even worse, why would a Dutch governemental organisation exaggerate these figures? Out of ignorance or...?

Leigh Jackson said...

itisi69 21
The IPCC and/or the PBL conspired to try to deceive the Dutch people and the rest of the world about how much of Holland lies below sea level? Are you serious?

Can you explain what such a conspiracy might have been designed to achieve?

Top of the list for a google under "netherlands flood risk ipcc" found the PBL English version:

"In the 2007 IPCC report by the Working group 2 (Climate change 2007: Impacts, adaptation and vulnerability) a mistake has entered the text that was supplied by the Netherlands Environmental Assessment Agency, regarding the risks of flooding for the Netherlands. In the chapter on Europe, on page 547, it says that 55 per cent of the Netherlands is below sea level (‘The Netherlands is an example of a country highly susceptible to both sea level rise and river flooding because 55% of its territory is below sea level’). This should have read that 55 per cent of the Netherlands is at risk of flooding; 26 per cent of the country is below sea level, and 29 per cent is susceptible to river flooding."

A flood map is also supplied.

A pattern begins to emerge of sloppy communications between government and non-govermental organisations and WG2 authors, and a lack of independent verifying of basic facts.

Leigh Jackson said...

I have been checking what AR4 says about African crop yields.

Synthesis report summary for policymakers, SPM3:

"By 2020, in some countries, yields from rain-fed agriculture could be reduced by up to 50%"

WG2 SPM. C.7 Africa:

"In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020"

Executive summary of Chapter 9 (Africa) of WG2, 9.ES:

"Projected reductions in yield in some countries could be as much as 50% by 2020"

9.4 states that several referenced authors including Agoumi warn against over-interpretation of results.

9.4.4: "In other countries, additional risks that could be exacerbated by climate change include greater erosion, deficiencies in yields from rain-fed agriculture of up to 50% during the 2000-2020 period, and reductions in crop growth period (Agoumi, 2003)"

So the executive summary of chapter 9 is at fault for failing to specify that *rain-fed* crop yields are at risk of 50% reduction.

New Scientist said "Crucially, the IPCC ignored that Agoumi's prediction applies only to rain-fed agriculture. In arid North Africa much farming is irrigated rather than rain-fed. So the IPCC's prediction that some African nations could lose half of their crops is in fact based on a fraction of agriculture in three North African nations."

I am afraid that NS have given a misleading impression of IPCC AR4. The executive summary of chapter 9 is misleading, but the synthesis report for policymakers is not nor is the summary for policymakers of WG2. The correct information is also found within chapter 9 following the executive summary.

The IPCC deserves betterr criticism than New Scientist has managed on this occasion.

eduardo said...



one main problem I see in the 'Africagate' is that even if the IPCC had quoted the work by Agumi correctly, it does not make very much sense physically. Consider that there has been a lot of discussion about whether or not the trend in global temperatures in the last 10 years is positive or negative, and whether this is weather or climate. If it is difficult to establish a trend in the global annual mean temperature, the variable presumably more strongly reflecting the external forcing, it is highly unlikely that North African seasonal precipitation reflects the external forcing in a short span of 15 years.
I think this should have been spotted in a serious review. For me it does not make sense really. A time horizon of 15 years is in climatic terms a very hard prediction, and this one was on top of that very clear: no less than 50% reduction.

Apart from the technicalities in the formulation, I think that we all would agree that this is not serious science

Leigh Jackson said...

eduardo 24
Agoumi specified the period 2000-2020. I understand that 20 years is an absolute minimum period for making any kind of meaningful statement about climate change as opposed to weather fluctuation. Agoumi did warn, as noted by the IPCC, that his results should not be overinterpreted.

If his study was not contradicted by any other then I think it was reasonable to quote it with appropriate caveats. I have not studied the report enough to make a judgement about that.

Leigh Jackson said...

Marco, I have no idea at all of the technicalities involved, but Agoumi is talking about a reduction of 50% only for rain-fed crops. The question is how a reduction in precipitation or perhaps simply rise in temperature translates into African crop yields. Agoumi, I assume, is an expert in such matters.

Leigh Jackson said...

I apologise Eduardo, for calling you Marco!

eduardo said...

@ 25, 26
Dear Leigh,
whether twenty years is enough or not depends on the noisiness of the variable. It is even difficult to establish a trend in the global annual average precipitation in the 20th century. We would be dealing here with regional precipitation, in a region characterized by high variability and a period of 20 years where the GHG forcing is still moderate. Where the study by Agumi true we should be seeing now a systematic decrease in rain-fed yield of 25% relative to the early 2000s. I do not think this has happened.
If you are interested have a look at the figures in
They show the spread in simulated winter precipitation for the Iberian peninsula.

Leigh Jackson said...

Thanks Eduardo, I had a quick look. I am at all qualified to draw any inferences on the basis of that graph. I do not know whether the graph can be related in any way to crop yields in the Iberian peninsula.

Have you read Agoumi 2003?

Leigh Jackson said...

Sorry, I am tired, I should have said "NOT at all qualified" - as I am sure you realise. Now I really must go to bed!

Leonard Weinstein said...

Professor von Storch,
CO2 appears to have increased since 1850 (the portion before 1958 is less well proven), and a reasonably well supported measurement of amount of increase was shown to have occurred since 1958. Some, or possibly most of the increase is due to human activity. The temperature has also increased somewhat since 1850, with much of the increase actually before 1940 (and the portion before 1940 is considered not mainly due to human activity). It is reasonable that any long term change in temperature will cause some impact on life. However, it appears that the increase is not inconsistent with previous changes over the last several thousand years. Ice forms and melts, seas rise and fall, etc., with the changes in temperature. Could you please explain where in this story the evidence for the temperature rise from 1970 to 2002 can be supported by CAGW or even AGW (vs. say just GW)? I keep seeing the statement that the large body of work in the IPCC supports that conclusion, but all I see that is supported is that there was a temperature change and it changed the surroundings. If the change were natural, the effect would be the same. The increase in CO2 and methane have not been shown to be the cause of anything. The issue seems to be hanging on the size of feedback, and reasonableness of models, neither which seems strong.

Hans von Storch said...

Leonard Weinstein / 31 - this issue has been discussed earlier on this blog, under the headline of detection and attribution. I have tried to explain the rational of the analysis; also comments are found there.

Leonard Weinstein said...

Professor von Storch,
I read the detection and attribution writeup. While I accept that the temperature has increased over the last 150 years, the errors due to measurement limitations and bad practices make the exact level less certain. I would not be surprised if the increase over that time was about 1/3 less than presently claimed, based on the specific examples in Siberia and several other locations, and proper use of corrections of urban effects. While this is not a big change, the total increase is not that large also. I do not see how you can claim that the rise RATE is unusual as well as the level even if the correction is not made. No long term global data is available, but local long term data (ice cores) support rapid rises and falls within the last several thousand years. Also, it is clear that long cycle ocean currents, Solar effects (magnetic field variations), clouds, and aerosols (as examples) are NOT well modeled. I am not a CFD person, I am a fluid mechanics experimentalist, but I have worked with people on modeling, and know that with a few knob adjustments on less understood parameters you can fit any set of given data. It is when the new data beyond the adjustment range appears that the value of the adjusted model is determined. So far, the models fail all strict tests in prediction.

Marco said...


Oi, no apologies to me, for thinking Eduardo's comments were mine?!?!

Marco said...

@Leonard Weinstein:
The closer we get to the present, the more certain we are of the temperature measurements. We have satellites for the last 30 years, which essentially give the same amount of surface warming as the land-based record.

The Siberia analysis by the Russian think-tank shows little. If anything, it showed much less warming pre-1940, which would reduce the warming rate in the first half of the 20th century, but not that in the later half...(which is the most important time period for anthropogenic CO2 emissions).

Leigh Jackson said...

Give me break, please - I was very tired!


eduardo said...

@ 30

in that graph representing the projections fro precipittaion change in the Iberain Peninsula you can see that some models simulate more winter precipitation than now, others less. Only when you take the mean of all models you can recognize a downward trend in the future. However, the average of all models cannot replicate the past. Until 2020 the changes are rather small, though. The situation for North Africa would be similar, although I havent checked this. Agumi didnt check either and doesnt show any of this. His estimation of 50% is just based on experience from drought years, assuming that anthropogenic climate change will exacerbate drought. Rain-fed crop production would be burdened with still more uncertainty, as one would drive a crop model with the climate projections, being themselves quite noisy.

Leigh Jackson said...

eduardo 37
You say the situation would be similar for North Africa but you haven't checked this. Given the nature of the criticisms of the IPCC would it not be prudent to do so?

Is Agoumi's method of estimation of little value, in your opinon? Or could the results be put into better context by bringing them together with the results of your methodology of predicting future precipitation? Are the methods sufficiently compatible to produce better information than either one alone?

Leigh Jackson said...

Also, Eduardo, were such precipitation models avaialble for North Africa at the time AR4 was being prpepared?

eduardo said...

@ 38
yes, it would be advisable to check what the models say about North African precipitation. However, I think that it is the authors of the WG2, who put that statement in the report, who should have checked and contrasted Agoumi's paper. What I and others are saying is that that assertion is not substantiated by the facts presented in that paper.

Anyway, I have checked it now. It took me about 10 minutes to produce this picture

I cannot see any trend in annual precipitation that could substantiate a 50% reduction in rain-fed crop yield- I am not an agriculture expert though. But the authors of WG2 could and should have consulted someone to produce these figure for them.

A related aspect is the following. Let us imagine that policy makers do read the IPCC WG2 report, and they see the 'reduction in crop yield..50%.. in 2020'. They would have found find this sentence so alarming that they should immediately start irradiation projects, asking for funding, etc.. it would have been a real threat for several millions of people in a very short term. But, as far as I know, nothing of this short happen. Blue chips European companies have started a project worth 400 billions to harvest solar energy in North Africa, but apparently there was no money or no interest to 'solve' this apparent urgent threat. Now that this threat appears not to be justified, there are no sighs of relief for the millions of lives suddenly not in danger anymore.
isnt it a bit strange?
My interpretation is that actually nobody either read this part of the report or nobody believed it. The present discussion and perhaps the WG2 report, is not about the environment but about scoring political points.

eduardo said...


these are the results of the global climate simulations (not just precipitation models). The WG1 IPCC AR4 report , chapter 10, is devoted to the analysis of these simulations.

They are actually *the* IPCC simulations. So it seems reasonable to think that the WG2 authors should have consulted them .

Leigh Jackson said...

For me, Eduardo, the present discussion is about testing the claim that WG2 is not about the environment but about scoring political points. I am unconvinced.

That the IPCC is a fallible institution is no surprise. That it is completely politically corrupt, or scientifically dishonest or invalid is not demonstrated as far as I am able to judge.

The points which you make here are interesting. I wonder what the IPCC would have to say in response. Please appreciate that I am not myself qualified to say whether your criticisms are valid or not. I look to scientific consensus to be my guide. If scientific national academies around the world endorse the IPCC then that is good enough for me. Although they are political organisations by nature - being the interface between science and scientists and greater society - yet I prefer to listen to their collective judgement about matters of science than those of individual scientists or discrete groups of scientists.

I simply do not have the expertise to challenge any individual scientist or group of scientists be they large or small. I therefore accept what the national academies are agreed about in matters of science on every single issue, without exception.

I am very interested, however, in dissentions from the scientific consensus of any form from within and without the scientific community.

eduardo said...

@ 42

your position is fair enough. I understand that for non-experts the present situation is confusing.
As you said, the IPCC, as all institutions, may make errors. The difference is that there is no mechanism at present to correct those errors in an orderly way. It seems that the review mechanisms are not working properly - I am referring here to WG2.

Therefore, the stance of dismissing all criticism to the IPCC as 'contrary to consensus' is dangerous. This leads to the wild attacks to the IPCC that we are seeing.

Leigh Jackson said...

Certainly to dismiss expert criticism because it is contrary to the consensus is wrong. I do not dismiss expert dissention, I accept the consensus - whatever it is - beacause, as a non-expert, I cannot be the judge between the experts.

Dissension from the consensus is a vital part of science, sometimes it leads to vast improvement in understanding, often it goes nowhere.

Another point about the politics. For those who are opposed to a scientific consensus for ideological reasons, the aim of causing doubt amongst the general public is a common motif.