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The global cooling myth Le mythe du refroidissement global

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Every now and again, the myth that “we shouldn’t believe global warming predictions now, because in the 1970’s they were predicting an ice age and/or cooling” surfaces. Recently, George Will mentioned it in his column (see Will-full ignorance) and the egregious Crichton manages to say “in the 1970’s all the climate scientists believed an ice age was coming” (see Michael Crichton’s State of Confusion ). You can find it in various other places too [here, mildly here, etc]. But its not an argument used by respectable and knowledgeable skeptics, because it crumbles under analysis. That doesn’t stop it repeatedly cropping up in newsgroups though.

Par William Connolley (Traduit par Pierre Allemand)

De temps en temps, le mythe selon lequel “nous n’allons pas croire aujourd’hui les prédictions concernant le réchauffement global car dans les années 70, on prédisait un nouvel âge glaciaire et/ou un refroidissement”, refait surface. Récemment, George Will le mentionnait dans son éditorial (voir Will-full ignorance) et le fameux Crichton s’arrange pour dire “dans les années 70, tous les chercheurs dans le domaine climatique pensaient qu’un nouvel âge glaciaire allait arriver” (voir Michael Crichton’s State of Confusion ). Vous pouvez le trouver également dans divers autres endroits [ici, ici (en termes plus nuancés), etc]. Cependant, cet argument n’en est pas un pour les sceptiques respectables et bien informés, car il ne résiste pas à l’analyse. Cela n’empêche pas, néanmoins, qu’il soit régulièrement repris dans les groupes de discussion.

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Is Climate Modelling Science? La modélisation climatique est-elle de la science?

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At first glance this seems like a strange question. Isn’t science precisely the quantification of observations into a theory or model and then using that to make predictions? Yes. And are those predictions in different cases then tested against observations again and again to either validate those models or generate ideas for potential improvements? Yes, again. So the fact that climate modelling was recently singled out as being somehow non-scientific seems absurd.
par Gavin Schmidt (traduit par Gilles Delaygue)

A première vue, cela semble une question étrange. Est-ce-que la science n’est pas précisément la quantification d’observations dans une théorie ou un modèle, et ensuite son utilisation pour faire des prédictions ? Oui. Et est-ce-que ces prédictions de différents cas sont ensuite confrontées, maintes fois, aux observations, afin soit de valider ces modèles ou bien de faire émerger des idées d’amélioration ? Oui, encore une fois. Ainsi la mise à l’index récente de la modélisation climatique comme quelque chose de non scientifique semble absurde.

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Senator Inhofe on Climate Change

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by Michael Mann, Stefan Rahmstorf, Gavin Schmidt, Eric Steig, and William Connolley

Senator James Inhofe (R) of Oklahoma recently provided us with an update of his views on the issue of climate change in a speech given on the opening senate session, January 4, 2005. His speech opened with the statement:

As I said on the Senate floor on July 28, 2003, “much of the debate over global warming is predicated on fear, rather than science.” I called the threat of catastrophic global warming the “greatest hoax ever perpetrated on the American people,” a statement that, to put it mildly, was not viewed kindly by environmental extremists and their elitist organizations.

Cutting through much of his polemic, Inhofe’s speech contains three lines of scientific argument which, according to him, provide “compelling new scientific evidence” that anthropogenic global warming is not threatening. We here submit his statements to scrutiny.
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On Yet Another False Claim by McIntyre and McKitrick

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McIntyre and McKitrick (MM), in one of their many false claims regarding the Mann et al (MBH98) temperature reconstruction, assert that the “Hockey Stick” shape of the reconstruction is an artifact of the “non-centered” Principal Components Analysis (PCA) convention used by MBH98 in representing the North American International Tree Ring Data Bank (ITRDB) data series. We already demonstrated the falsehood of this assertion here by showing (a) that the hockey stick pattern emerges using either the MM (centered) or MBH98 (non-centered) PCA conventions, but was censored by MM through an inappropriate application of selection rules for determining the number of Principal Component (PC) to retain, (b) that use of the correct number of PC series (5) to be kept with the MM (centered) convention retains the characteristic “Hockey Stick” pattern as an important predictor, and yields essentially the same temperature reconstruction as MBH98, and finally [Read more…] about On Yet Another False Claim by McIntyre and McKitrick

Imprecision of the Phrase “Global Warming”

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Guest Contribution by Michael Tobis, University of Chicago

Consider the possibility that the expression “global warming” has become a problematic one, and that it might be best to avoid it.

A big part of the public confusion about climate change comes from sloppy language. The naysayers prey on this confusion, very much as their peers prey on the phrase “evolutionary theory” to suggest that “evolution, well, it’s just a theory”.

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Will-full ignorance

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It is not worthwhile for RealClimate to post a response to each misinformed newspaper commentary on climate change that we come across. However, George Will’s recent article in the Washington post (in which he praises Michael Crichton’s State of Fear) perhaps deserves special attention because Will is so widely read and respected. We find it disappointing that Will appears not to have bothered looking up the most basic facts before writing his article. See also our earlier post on the George Will article.

We have already posted detailed responses to State of Fear. Here, we respond briefly to the points Will tries to make. The italics are direct quotes from his article.

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George Will-misled and misleading

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In a Washington Post Opinion article on December 22, 2004, commentator George Will applauds Michael Crichton’s new book, State of Fear. We have already pointed out some of the more egregious scientific errors in Crichton’s novel (see Michael Crichton’s State of Confusion ). Mr. Will compounds those errors and fails his own standards by making statements that are truly “innocent of information but overflowing with certitudes”.

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A Welcoming Nature

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Getting a serious paper into Nature or Science is deservedly hard. Getting a mention for your climate blog is apparently a little easier!

We are of course collectively very pleased that Nature has welcomed the RealClimate.org effort so forthrightly. We only hope that we will be able to match up to their expectations. As with anything new, done by inexperienced first-timers who really should be concentrating on their actual jobs, there are bound to be teething problems. One, alluded to in the editorial and accompanying news story, is who gets to decide what’s posted, and getting the balance right between inclusiveness and clarity.

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How do we know that recent CO2 increases are due to human activities? Comment savons-nous que l’augmentation récente du CO2 est due aux activités humaines ? (mise-à-jour)

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Note:This is an update to an earlier post, which many found to be too technical. The original, and a series of comments on it, can be found here. See also a more recent post here for an even less technical discussion.

Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). The fact that this is due virtually entirely to human activities is so well established that one rarely sees it questioned. Yet it is quite reasonable to ask how we know this.

Det finns en svensk översättning tillgänglig här
Una traducción en español está disponible aquí.

par Eric Steig (traduit par Gilles Delaygue)

Note :Ceci est une mise-à-jour d’un article précédent, que beaucoup ont trouvé trop technique. L’original, ainsi qu’une série de commentaires, se trouvent ici.

Pendant les 150 dernières années, la concentration en dioxyde de carbone (CO2) a augmenté de 280 à 380 parties par million (ppm). Le fait que cette augmentation soit due pratiquement entièrement aux activités humaines est si bien établi qu’on le voit rarement remis en question. Pourtant, il est tout à fait raisonnable de se demander comment nous le savons.

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Just what is this Consensus anyway? En quoi consiste le “Consensus” ?

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We’ve used the term “consensus” here a bit recently (see our earlier post on the subject), without ever really defining what we mean by it. In normal practice, there is no great need to define it – no science depends on it. But it’s useful to record the core that most scientists agree on, for public presentation. The consensus that exists is that of the IPCC reports, in particular the working group I report (there are three WG’s. By “IPCC”, people tend to mean WG I). Fortunately that report is available online for all to read at http://www.grida.no/climate/ipcc_tar/wg1/. It’s a good idea to realise that though the IPCC report contains the consensus, it didn’t form it. The IPCC process was supposed to be – and is – a summary of the science (as available at the time). Because they did their job well, it really is a good review/summary/synthesis.

Par William Connolley (traduit par Pierre Allemand)

Nous avons utilisé le terme “consensus” ici très récemment (voir l’ article précédent sur le sujet) sans réellement définir ce que nous entendions par là. Normalement, il n’y a pas vraiment besoin de le définir – rien de scientifique n’en dépend. Mais, il est d’usage de noter le cœur du sujet sur lequel la plupart des scientifiques sont d’accord, pour des présentations publiques. Le consensus existant est celui des rapports du GIEC, en particulier le groupe de travail n°I (il y a trois groupes de travail. Par “GIEC”, on a tendance à vouloir parler du groupe de travail n°I).
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