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Documentation > Greenhouse effect > Scientists > What is the IPCC?

What is the IPCC ?

september 2003

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The IPCC (abreviation that stands for Intergovernmental Panel on Climate Change) is an organization that was set up in 1988, following a demand by the G7 (a group that gathers the 7 richest countries in the world: USA, Japan, Germany, France, Great Britain, Canada, Italy), by

The World Meteorological Organization


the United Nations Environnement Programme

Any country which is a member of either of these two organizations (that have countries as members, not individuals) can be a member of the IPCC. As almost any country in the world is a member of the United Nations (two exceptions are the Vatican - as surely many other people, I would be much interested to know how the Pope considers climate change ! - and Taiwan, but I don't know if there are any others), practically all countries in the world are members of the IPCC.

The role of the IPCC is to "assess the scientific, technical and socio-economic information that relates to human induced climate change".

It is therefore not a research lab, but a organism that assesses and summarizes research work done throughout the world. This is an important point, because any reasearch worker that belongs to a relevant discipline - including, of course, someone that would support the absence of influence of man on the climate - can ask for an assessment of his work in the reviewing processes managed by the IPCC.

The supreme body of the IPCC is the general assembly, where every member country has one vote (Samoa Islands therefore weight the same than the US). It's the general assembly that sets up the working programme that the IPCC will follow later on, that is the subjects for which it will have to conduct a reviewing process of the available scientific knowledge, and it is the assembly that approves the most important reports, called "assessment reports", before publication.

The executive body of the IPCC is the board (just like for a regular association), which is elected by the general assembly. The IPCC has its own budget. The IPCC is divided in three working group that each have the role of conducting assessments on:

The works published, or in progress, that concern the physical (and chemical !) processes of the climate, and their past or future variations (group 1).

The works published, or in progress, that concern the possible impacts of a human induced climate change on the biosphere and our socio-economic systems, and the possible ways to adapt (group 2).

The works published, or in progress, that concern the future greenhouse gases emissions and the mitigation possibilities of climate change (group 3).

In addition to the major reports scrutinized by the general assembly (the "assessment reports"), the IPCC also publishes various reports on specific subjects, such as the contribution of air travel, the land use change consequences, the detailed presentation of emission scenarios, or the present level of understanding on rapid changes.... These papers are not submitted to the general assembly (and therefore not approved by it) but are elaborated with the same kind of procedures that those used for the "official" publications.

How are assessment reports made ?

On the grounds of the programme that has been decided by the general assembly for the 3 working groups, this programme consisting in fact, for each working group, in the future table of contents of the report to be (all the chapters are already decided !), the IPCC board will solicit as coordinating lead authors recognized experts of the involved disciplines. These coordinating lead authors will then solicit lead authors and contributing authors, that will each write part of the chapter of the report and/or coordinate the work of other authors.

With several tenths of authors contributing to each chapter, an assessment report will require the contribution of hundreds of authors, not mentionning the even more numerous individuals that will just give an opinion on the projects (formally or not).

The general architecture of a report is the following: each chapter deals with a specific subject (for exemple the physical properties of the greenhouse gases, the adequacy of the representation of the climate processes in the numerical models, the past climatic variations, the evolution of the greenhouse concentrations in the atmosphere, etc), and the authors of the related chapter are in charge of wrinting a synthesis of the available scientific knowledge on the corresponding topic.

What they are asked is not to give an opinion "like that": they carry out a long - and sometimes not that funny - compilation of all the available scientific litterature, or of the works in progress in the research labs that investigate the subject. For example, the chapter "model evaluation" (in the report of the working group 1) is written by model specialists that analyze hundreds of articles opn model evaluation (meaning: do models correctly reproduce this or that phenomenum) published in the scientific litterature (the bibliography is always indicated at the end of each chapter).

These sectoral syntheses allow to produce a first draft of report, that will be read and criticized by other experts of the concerned disciplines, what will lead to a second draft, that will be sent to the same experts than for the first draft, and, in addition, to representatives of the governments of member countries. It's only after the draft went to and fro twice, with very formal procedures, that a definite document is submitted to the general assembly of the IPCC, in order to be approved before publication.

Overall, several thousands people - generally renowned researchers, but the process is open to anybody who wishes to be heard, as mentionned below - are involved into the writing and the reviewing of the report that will be published.

Before being published and declared "official reports" of the IPCC, these assessment reports are explicitely approved by the full assembly of the member countries, where representatives are generally competent - but not always - in science. Up to this day, all the assessment reports of the IPCC have been unanimously approved by the member countries, including by the USA, or by Saudi Arabia.

The first assessment report has been published in 1990 ; about everything mentionned on these pages was already there. A second detailed report was issued in 1996 and a third in 2001 ; a fourth is presently in wrinting. The documents produced by the IPCC are used as a reference in the international negociations on greenhouse gases, but, in order to avoid any confusion, the IPCC has no official representative at these negociations.

The IPCC has a web site ( where one can consult or download, in several languages:

summaries for policymakers, that synthetize the major assertions and conclusions of what is written in the full report (these summaries for policymakers are even approved word by word by the general assembly),

the full text of the third assessment report ,

the full texts of other reports, and presentations of reports that are not available in full text,

technical papers that focuse on a particular subject (for example what we know on abrupt changes within some elements of the climate system),

various papers on the work in progress (program of meetings, subjects to be discussed, where and by whom, etc).

The full reports, that are all public, are generally published - only in english - by Cambridge University Press. They can be ordered on the web site (do a search with the exact phrase "climate change 2001").


Should we believe the IPCC ?

Now that's the interesting question ! Let's break the news fast: the answer is yes.

The official publications of the IPCC have for sole purpose to offer a synthesis of the scientific state of the art, what includes both points that are considered well established and points that are still considered (very) speculative by the authors, without forgetting the limits within which the exposed results are valid. These publications result from a long debate between experts, who are the only ones to know whether a given uncertainty prevents from giving a general conclusion or not. The general assembly, where all the countries that have at least one competent scientist, has always approved unanimously the proposed assessment reports.

It is therefore legitimate to consider that all that is consensual in the IPCC reports can be held as an established fact. This particularly includes:

The CO2 concentration in the atmosphère is now 30% higher than during any time of the previous 400.000 years,

increasing the CO2 concentration in the atmopshere will generate a climate change, that will include an increase of the average near ground air temperature. It's the magnitude of the temperature increase that remains - and will remain for long - an open debate, but not the fact that globally the temperature will rise.

Given this, what should we think of the various individuals that periodically throw themselves in front of cameras or get headlines in the papers and contest "the scientific file" ? Here are a couple of reflexions :

First of all any assessment process conducted by the IPCC is opened to any scientist that wishes to formulate a remark or submit a work, and this process is preciseley designed so that the debate can happen between people who know what they are talking about, and not brought in front of a general public that is not able to judge. The IPCC is not hosting a conspiracy !

Debating is a normal part of the activity of any researcher, but somebody who is a competent - and honest - researcher in a given discipline will always do the the same if he (or she) questions an explanation considered as established: this somebody will begin by submitting to his peers, through the publication of an article in a scientific paper (where articles are reviewed by other experts before being published) such as Nature, Science, Quaternary Review, Physics Today, etc (neither Scientific American nor the Washington Post or The Financial Times or The Economist are such scientific papers) a detailed explanation indicating why the commonly admitted theory is wrong, by what means and deductions he or she managed to get to this conclusion, and what experimental confirmations of the new explanation can be obtained. A normal researcher will never begin by throwing himself in front of cameras or by wrinting in the general press to expose his views: as there is no validation process by competent people, such publications will never be put to his credit by his peers.

Apart from one exception (discussed below), all the "contestations" that I have read up to now in the general press come from people that do not have any particular scientific competence on climate change. Practically, all the "skeptics" I heard of belonged to one or another of these categories:

non-scientific authors whose long lasting personnal theories or personnal interests are hardly compatible with the probable implications of fighting against climate change. That includes "diehard liberals", globally against any constraint whatsoever, a category to which probably belongs M. Philip Stott (writer of an article in the Wall Street Journal which is a pure marvel of nonsense), oponents to nuclear energy (which is a possible action level of any policy aimed at a fast decrease of greenhouse gases emissions), individuals that belong to an industrial sector heavily dependant on fossil fuels (coal mines, oil companies, but also steel companies, chemists...)...

researchers or engineers that belong to a field which has no particular ties with the climate change problem (any "scientists" is not competent in any scientific field, just as any physician is not competent in heart surgery, or any mechanics is not able to fix an Atlas rocket !) but that nevertheless express themselves on the subject for various reasons (personal ego, political role, people put under pressure by the press or by publishers that seek - very hard sometimes - contradictors....).

This category includes Blorn Lomborg (who is a statistician, therefore holds a university position, but in a speciality that has no connections with climate change ; look here for a commentary on the "climate change" chapter of his book "the skeptical environmentalist"), or someone like Claude Allègre (a competent french geophysicist that became Secretary of state, in charge of schools ans universities), or the late Haroun Tazieff (a weell know vulcanologist in France that also had a political role) - but that was a long time ago.

scientists that do not criticize the least the IPCC reports, but that seem to do so after a skillfull editing done by a journalist, who did not necessarily do it intentionnally by the way. When, after one hour of interview, if not more, just 2 sentences are broadcasted on the radio, on TV, or printed in the paper (this situation being more the rule than the exception, I can personnally testify !), on one hand it is not the person interviewed that chose them but the journalist (in short it's the journalist that decides what the scientist will say), and on the other hand the interviewed scientist will not necessarily be able to validate his words (generally he (she) doesn't have this possibility). There is no doubt this way of proceeding facilitates misinterpretations.

various bad faith behaviours, that might come from competent scientists. A famous representative of this category is an MIT professor, Richard Lindzen, who contributed a lot to trouble minds (it was intentional, of course) by expressing publicly his doubts on some elements of the file in such a way that it was easy to consider that he was dismissing the whole file (which is not the case, even though he lets journalists say so). My guess is that he was offended not to be among the lead authors of the first IPCC assessment report in 1990, in spite of the fact that he was - and is - an eminent specialist of atmospheric processes.

He eventually ended being a lead author in the 2001 assessment report, and several months later - pure coincidence ? - he co-signed a paper published by the american National Academy of Science, written on Bush Jr's demand (the object was to assess...the IPCC assessment process), in which the following sentences can be found (page 4): "The committee finds that the full IPCC working group 1 report is an admirable summary of research activities (...). It is critical that the IPCC process remains truly representative of the scientific community.(...)" (the second sentence clearly suggests that the IPCC process IS representative today). So what should we think of M. Lindzen's declarations to the press after that ?

journalists that misunderstood the conclusions of the IPCC reports. The assessment reports are not accessible to the general public : they are in english (may I remind my reader that MOST people - and therefore most journalists - in the world are not fluent in english ?), 800 pages thick, and it is really scientific litterature, every page containing expressions like "the effects of fresh water pulse on AABW formation", or "AVHRR-derived albedo estimates can now be mapped".... In France, I am totally sure that there is not one journalist of the general media that has read the whole group 1 report, or even two chapters in extenso while understanding everything. When a journalist writes about what there is in the report, he does so without having read it: this can lead to some little side effects !

journalists that reproduce a contestation without knowing whether it is sound because "there must always be someone for and someone against" (a lot of journalists deeply hate universal truths, even when they exist ; this does not happen often with human behaviour, what consitutes their everyday life, but happen often in sciences: 2+2 always make 4 ; must some audience be given to someone who would argue that 2+2=3 just to "diversify the opinions" ?). This lust for contradictors of the media has certainly played a central role in the rise of all the "skeptics" I heard of.

people that only read the newspaper and that are inspired, for there own literary production, by a journalist who wrote nonsense : such an individual will explain that this or that conclusion of the science is false, when it is not mentionned in the IPCC report, but just in the article of a journalist that badly understood !

This observation generates the following advice, for those interested by climate change: never ever consider an article of the general press as a reliable source of information, but always go back to the original documents. All those that are in the position to compare what they personnally know on a complex or technical subject and how the corresponding facts are generally presented in the press will surely understand me !

And at last one must recall that all the "counter-arguments" invoked by the "skeptics" that are of scientific nature (role of the sun, for example) have been long known by the competent scientists, since they are precisely examined and discussed in the assessment reports.

Finally, an individual who is not a competent scientist directly involved in climate change - which is my case, all I have done is reading a non ridiculous amount of scientific litterature and discussing with a small part of the competent scientists - is not able to have a technical judgment on a field he does not know (I would not dare judging the way ice cores have been extracted, or whether the calibration of the mass spectrometer was correctly done: on what basis could I do so ?). All we can do is ask ourselves these two simple questions :

do several thousands of high ranking scientists, perfectly respected otherwise (they include members of the academy of sciences is many countries...), have particular reasons to deliberately say nonsense in the present case ? It is doubly improbable:

The results on which thay lean are perfectly admitted in other contexts,

There would be no mobile to the crime. The sometimes heard argument about drawing attention to have research credits might seem admissible, but actually it's rather the opposite that happens: in Europe, the more the file appears solid, and the less public money is poured, because governments consider that the file is sufficient to act and that there is no need to fund additional research. And it's in the US that the most money is poured at the present time: with the present government, money there is probably easier to get for people that would try to demonstrate that there is no risk !

In addition, such a reasoning (a world conspiracy to get money for research) might apply to a couple of people, but suggesting that thousands of researchers, that are generally honest people, coming from dozens of different disciplines, can try to enforce this same idea at the same time, seems totally improbable. Anyway, speculating on this possibility to consider that we don't have any reason to be worried is a bet that I will not take.

What do we risk if we don't believe them ? Just to loose part of a comfortable planet, and the life of part of our descendants, which isn't nothing...


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