RealClimate

Climate science from climate scientists...

You are here: Home / Archives for Climate Science

Climate Science

A Welcoming Nature

by

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.

[Read more…] about A Welcoming Nature

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)

by

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.

(suite…)

[Read more…] about 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)

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

by

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).
(suite…)
[Read more…] about Just what is this Consensus anyway? En quoi consiste le “Consensus” ?

Fox News gets it wrong

by

In a December 17th Fox News story (See full report here) Steven Milloy comments on a lecture by Lonnie Thompson at the Annual meeting of the American Geophysical Union in San Francisco. He uses a common ploy of truncating what Thompson said, to ensure that a quotation fits with his message. According to Milloy, Thompson said, “Any prudent person would agree that we don’t yet understand the complexities with the climate system.” But what he actually said was “Any prudent person would agree that we don’t yet understand the complexities with the climate system and, since we don’t, we should be extremely cautious in how much we ‘tweak’ the system.” (see full press release here). Such manipulations are designed so that Milloy can’t be accused of misquoting, but clearly, he completely contorts Thompson’s point. Milloy also misunderstands the science.

[Read more…] about Fox News gets it wrong

Statistical analysis of consensus Analyse statistique du consensus

by

Is there really “consensus” in the scientific community on the reality of anthropogenic climate change? As N. Oreskes points out in a recent article in Science, that is itself a question that can be addressed scientificially. Oreskes took a sampling of 928 articles on climate change, selected objectively (using the key phrase “global climate change”) from the published peer-reviewed scientific literature. Oreskes concluded that of those articles (about 75% of them) that deal with the question at all, 100% (all of them) support the consensus view that a significant fraction of recent climate change is due to human activities. Of course, there are undoubtedly some articles that have been published in the peer-reviewed literature that disagree with this position and that Oreskes’s survey missed, but the fact that her sample didn’t
Par Eric Steig (traduit par Pierre Allemand)

Y a-t-il réellement “consensus” dans la communauté scientifique sur la réalité du changement climatique anthropogénique ? Comme N. Oreskes le fait remarquer dans un récent article de Science, c’est une question qui peut être elle-même traitée scientifiquement. Oreskes a pris un échantillon de 928 articles sur le changement climatique , objectivement choisis (utilisation de la phrase clé “changement climatique”) dans la littérature scientifique relue par des pairs. Oreskes en a conclu que parmi les articles (environ 75 % du total) qui traitent de la question 100 % (tous) partagent la vue consensuelle selon laquelle une part significative du changement climatique récent est due à l’activité humaine.

(suite…)

[Read more…] about Statistical analysis of consensus Analyse statistique du consensus

Michael Crichton’s State of Confusion II: Return of the Science

by

Our first post on Crichton’s new novel “State of Fear” hits most of the key points, though there are a few more errors in the book that we hope to expand upon in future posts.

But for those of you uninterested in buying and reading the book, you can actually find a similar-minded opinion piece by Crichton criticizing climate science (and everything from SETI and the “Drake Equation” to Carl Sagan in the process) here in the public domain.

[Read more…] about Michael Crichton’s State of Confusion II: Return of the Science

Michael Crichton’s State of Confusion L’état de confusion de Michael Crichton

by

In a departure from normal practice on this site, this post is a commentary on a piece of out-and-out fiction (unlike most of the other posts which deal with a more subtle kind). Michael Crichton’s new novel “State of Fear” is about a self-important NGO hyping the science of the global warming to further the ends of evil eco-terrorists. The inevitable conclusion of the book is that global warming is a non-problem. A lesson for our times maybe? Unfortunately, I think not.

par Gavin Schmidt (traduit par Alain Henry)

Ce message s’écarte des pratiques habituelles de ce site pour commenter une pièce de pure fiction (au contraire des autres messages qui abordent le sujet sous un angle plus subtil). Le nouveau roman de Michael Crichton, « Etat d’urgence » raconte comment une ONG encourage la recherche scientifique sur le réchauffement global pour servir les objectifs de méchants éco-terroristes. Le roman nous amène inévitablement à la conclusion que le réchauffement global est un faux problème. Une leçon pour notre époque? Malheureusement, je ne le pense pas.
(suite….)

[Read more…] about Michael Crichton’s State of Confusion L’état de confusion de Michael Crichton

Climate Change Disinformation

by

by Michael Mann and Gavin Schmidt
As highlighted in the introduction to the site, we seek to clarify the findings of scientists who study the earth’s climate, and have an informed view on the science of climate change. Additionally we will speak out where we feel that the public discourse surrounding the science is being detrimentally impacted by the shrill voices and disinformation campaigns of the “partisan think-tanks or other interested parties”.

[Read more…] about Climate Change Disinformation

Welcome to RealClimate Bienvenue à RealClimate

by

Climate science is one of those fields where anyone, regardless of their lack of expertise or understanding, feels qualified to comment on new papers and ongoing controversies. This can be frustrating for scientists like ourselves who see agenda-driven ‘commentary’ on the Internet and in the opinion columns of newspapers crowding out careful analysis.
Les sciences du climat forment une discipline dans laquelle qui que ce soit, indépendamment de son expertise ou de sa compréhension, se sent qualifiée pour présenter ses observations sur de nouveaux articles et polémiques en cours. Ceci peut se révéler frustrant pour les scientifiques, comme nous-mêmes, qui lisont des ‘commentaires’ sur le web dictés par des préjugés politiques qui ne tiennent compte de la rigueur des observations scientifiques.

(suite…)
[Read more…] about Welcome to RealClimate Bienvenue à RealClimate

Weren’t temperatures warmer than today during the “Medieval Warm Period”? Ne faisait-il pas plus chaud au Moyen-Age, pendant “l’Optimum climatique”, que maintenant?

by

This is one of a number of popular myths regarding temperature variations in past centuries. At hemispheric or global scales, surface temperatures are believed to have followed the “Hockey Stick” pattern, characterized by a long-term cooling trend from the so-called “Medieval Warm Period” (broadly speaking, the 10th-mid 14th centuries) through the “Little Ice Age” (broadly speaking, the mid 15th-19th centuries), followed by a rapid warming during the 20th century that culminates in anomalous late 20th century warmth. The late 20th century warmth, at hemispheric or global scales, appears, from a number of recent peer-reviewed studies, to exceed the peak warmth of the “Medieval Warm Period”. Claims that global average temperatures during Medieval times were warmer than present-day are based on a number of false premises that a) confuse past evidence of drought/precipitation with temperature evidence, b) fail to disinguish regional from global-scale temperature variations, and c) use the entire “20th century” to describe “modern” conditions , fail to differentiate between relatively cool early 20th century conditions and the anomalously warm late 20th century conditions.

par Michael Mann (traduit par Thibault de Garidel)
C’est un des nombreux mythes populaires concernant les variations de température sur les siècles passés. A l’échelle globale ou hémispherique, il est admis que les températures de surface ont suivi une évolution en forme de “crosse de hockey” – (“hockey stick”), caractérisée par une longue tendance au refroidissement depuis “l’Optimum Climatique Médiéval” (grosso modo, du Xie au milieu du XIVie siècle) jusqu’au “Petit Age Glaciaire” (grosso modo du milieu du XVie au XIXie siècle), suivie d’un réchauffement rapide au XXie siècle qui culmine par les températures anormalement élevées de la fin du XXie siècle. Ces températures élevées de la fin du XXie siècle, aux échelles hémisphérique ou globale, apparaissent, d’après de nombreux travaux récents évalués par des pairs, supérieures à celles maximales de l’Optimum Médiéval.
Les assertions de températures moyennes globales plus élevées au Moyen Age que maintenant sont fondées sur un certain nombre de prémisses fausses qui (a) confondent les indicateurs de sécheresse/précipitation avec ceux de température, (b) ne font pas la différence entre des variations globales et régionales de température, et (c) utilisent tout le 20ie siecle pour définir les conditions ‘modernes’, ce qui empêche de différencier les conditions relativement fraiches du début du 20ie et celles anormalement chaudes de la fin du 20ie.