This is just to note some personnel changes at RealClimate. Amy Clement is unfortunately too overcommitted to be able to participate as much as she would like, and so is dropping out of the team. She states: “I fully support what the contributors of RealClimate are doing. It is a real service to both the community of climate scientists and to the general public”. To balance that, we welcome aboard paleoceanographer Thibault de Garidel (Rutgers) , who some francophiles may have noticed has been helping organise the French translations of some of the posts. And of course, if there are any other scientists out there who’d like to contribute, we would love to hear from you.
Strange Bedfellows En Etrange Compagnie
Here’s a curious observation. Some commentators who for years have been vocally decrying the IPCC consensus are lining up to support the ‘Ruddiman’ hypothesis. A respected paleoceanographer, Bill Ruddiman has recently argued that humans have been altering the level of important greenhouse gases since the dawn of agriculture (5 to 8000 years ago), and in so doing have prevented a new ice age from establishing itself. This intriguing idea is laid out in a couple of recent papers (Ruddiman, 2003; Ruddiman et al, 2005) and has received a fair degree of media attention (e.g. here, and here).
par Gavin Schmidt (traduit par Thibault de Garidel)
Voici une curieuse observation. Les mêmes commentateurs qui pendant des années ont décrié le consensus autour du GIEC s’alignent désormais pour soutenir l’hypothèse dite de ‘Ruddiman’. Bill Ruddiman, un paléocéanographe respecté, a en effet récemment suggéré que l’action humaine avait changé la concentration de certains gaz à effet de serre, depuis le développement de l’agriculture (il y a 5 à 8000 ans), empêchant ainsi la mise en place d’une nouvelle période glaciaire. Cette idée intrigante est présentée dans deux articles récents ( Ruddiman, 2003 ; Ruddiman et autres, 2005 ), et a suscité depuis une certaine attention des médias (voir par exemple ici , et ici ).
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11ºC warming, climate crisis in 10 years? 11ºC de réchauffement, une crise climatique dans 10 ans ?
by Gavin Schmidt and Stefan Rahmstorf
Two stories this week, a paper in Nature (Stainforth et al, 2005) describing preliminary results of the climateprediction.net experiments, and the Meeting the Climate Challenge report from a high level political group have lead to dramatic headlines. On the Nature paper, BBC online reported that “temperatures around the world could rise by as much as 11ºC “; on the latter report it headlined: “Climate crisis near ‘in 10 years’”. Does this mean there is new evidence that climate change is more serious than previously thought? We think not.
par Gavin Schmidt et Stefan Rahmstorf (traduit par Thibault de Garidel et Gilles Delaygue)
Deux travaux sortis cette semaine, un papier publié dans Nature (Stainforth et al., 2005) décrivant des résultats préliminaires de l’expérience climateprediction.net, et le rapport Meeting the Climate Challenge d’un groupe politique, ont mené à des titres catastrophistes dans les médias. Sur l’article de Nature, BBC on line indique que les “températures globales pourraient s’élever de près de 11ºC”; sur le second rapport il est écrit: “Une crise climatique proche pour dans 10 ans”. [N-d-T. : Voir également Le Monde : Un réchauffement climatique de plus de 6ºC n’est plus à exclure ; Libération : Prédire chez soi]. Cela signifie-t-il que de nouvelles preuves montrent un changement climatique plus sérieux que précédemment estimé ? Nous ne le pensons pas.
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Global Dimming? Assombrissement global?
It just so happens that most of the posts on this site have tried to counteract arguments from those who would sow fake “uncertainty” in the climate debate. But lest our readers feel that we are unjustifiably certain about our knowledge, let us look at a recent example of the opposite tendency: too much certainty.
A recent BBC Horizon documentary (transcript) raised the issue of ‘global dimming’ and argued that this ‘killer’ phenomena’s newly-recognised existence would lead to huge re-assessments of future global warming. As part of the hyperbole, the process of global dimming was linked very clearly to the famines in Ethiopia in the 1980s and the implication was left that worse was to come. Media reports with headlines like “Fossil Fuel Curbs May Speed Global Warming” swiftly followed. So what’s the real story?
Il est un fait que la plupart des interventions sur ce site ont essayé de contrer les arguments de ceux qui voudraient semer une “incertitude” trompeuse dans le débat sur le climat. Mais, de peur que nos lecteurs pensent que nous sommes abusivement certains de nos connaissances, examinons un exemple récent de la tendance inverse : trop de certitude.
Un récent documentaire de la série “Horizon” de la BBC (transcription) a soulevé la question d’un “assombrissement global” et a indiqué que l’existence récemment reconnue d’un tel phénomène « tueur » pourrait amener à reconsidérer très fortement l’hypothèse d’un futur réchauffement global. Cet audacieux raisonnement faisait un lien très clair entre l’assombrissement global et les famines en Ethiopie durant les années 1980, le plus grave restant encore à venir. Des dépêches de presse avec des titres du genre « Le coup de frein sur les énergies fossiles pourrait accélérer le réchauffement global » suivaient dans la foulée. Mais, qu’en est-il exactement ?
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[Read more…] about Global Dimming?
Is Climate Modelling Science? La modélisation climatique est-elle de la science?
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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[Read more…] about Is Climate Modelling Science?
Imprecision of the Phrase “Global Warming”
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”.
[Read more…] about Imprecision of the Phrase “Global Warming”
A Welcoming Nature
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.
Michael Crichton’s State of Confusion L’état de confusion de Michael Crichton
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.
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[Read more…] about Michael Crichton’s State of Confusion
Why does the stratosphere cool when the troposphere warms? Pourquoi la stratosphère refroidit alors que la troposphère se réchauffe ?
This post is obsolete and wrong in many respects. Please see this more recent post for links to the answer.
14/Jan/05: This post was updated in the light of my further education in radiation physics.
25/Feb/05: Groan…and again.
Recent discussions of climate change (MSU Temperature Record, ACIA) have highlighted the fact that the stratosphere is cooling while the lower atmosphere (troposphere) and surface appear to be warming. The stratosphere lies roughly 12 to 50 km above the surface and is marked by a temperature profile that increases with height. This is due to the absorbtion by ozone of the sun’s UV radiation and is in sharp contrast to the lower atmosphere. There it generally gets colder as you go higher due to the expansion of gases as the pressure decreases. Technically, the stratosphere has a negative ‘lapse rate’ (temperature increases with height), while the lower atmosphere’s lapse rate is positive.
Des études récentes du changement climatique (MSU température Record, ACIA) ont mis en évidence un refroidissement de la stratosphère, en parallèle a un apparent réchauffement de la surface et la basse atmosphère (troposphère). La stratosphère se situe entre 12 et 50 km d’altitude environ. Elle se caractérise par un profil de température qui augmente avec l’altitude, en raison de l’absorption des radiations solaires ultraviolettes par l’ozone stratosphérique. Les choses sont très différentes dans la troposphère (de 0 a 12 km d’altitude environ), ou, en général, la température baisse lorsque l’altitude augmente, en raison de l’expansion des gaz alors que la pression atmosphérique diminue. En d’autres termes, la stratosphère a un gradient de température négatif, alors que la troposphère a un gradient positif.
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[Read more…] about Why does the stratosphere cool when the troposphere warms?
Gavin A. Schmidt
Gavin Schmidt is a climate modeller at the NASA Goddard Institute for Space Studies and Earth Institute at Columbia University in New York and is interested in modeling past, present and future climate. He works on developing and improving coupled climate models and, in particular, is interested in how their results can be compared to paleoclimatic proxy data. He has worked on assessing the climate response to multiple forcings, including solar irradiance, atmospheric chemistry, aerosols, and greenhouse gases.
He received a BA (Hons) in Mathematics from Oxford University, a PhD in Applied Mathematics from University College London and was a NOAA Postdoctoral Fellow in Climate and Global Change Research. He was cited by Scientific American as one of the 50 Research Leaders of 2004, and has worked on Education and Outreach with the American Museum of Natural History, the College de France and the New York Academy of Sciences. He has over 100 peer-reviewed publications and is the co-author with Josh Wolfe of “Climate Change: Picturing the Science” (W. W. Norton, 2009), a collaboration between climate scientists and photographers. He was awarded the inaugural AGU Climate Communications Prize and was the EarthSky Science communicator of the year in 2011. He tweets at @ClimateOfGavin.
More information about his research and publication record can be found here.
All posts by gavin.