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Aerosol Aérosol

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A collection of airborne solid or liquid particles, with a typical size between 0.01 and 10 µm and residing in the atmosphere for at least several hours. Aerosols may be of either natural or anthropogenic origin. Aerosols may influence climate in two ways: directly through scattering and absorbing radiation, and indirectly through acting as condensation nuclei for cloud formation or modifying the optical properties and lifetime of clouds (from the always useful IPCC glossary).

See-also: wiki:Aerosol.

Particules pouvant être solides ou liquides, en suspension dans l’air, qui ont une taille comprise 0.01 et 10 µm, et qui résident dans l’atmosphère au moins quelques heures. L’origine des aérosols peut être soit naturelle, soit anthropogénique. Les aérosols peuvent influencer le climat de deux manières : soit directement par la dispersion et l’absorption des rayonnements, soit indirectement en servant de noyaux de condensation pour la formation des nuages ou en modifiant les propriétés optiques et la durée de vie des nuages. (définition provenant du très utile glossaire du GIEC).

Welcome to RealClimate Bienvenue à RealClimate

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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.

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[Read more…] about Welcome to RealClimate Bienvenue à RealClimate

Comment policy

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  1. Comments are moderated. Comments are periodically reviewed, but especially at weekends, evenings and holidays, there may be some delay in approving otherwise non-contentious posts. Please be patient.
  2. Questions, clarifications and serious rebuttals and discussions are welcomed.
  3. Only comments that are germane to the post will be approved. Comments that are “off-topic” should be made on an open thread (usually entitled “Unforced Variations”), and we may move OT comments to those threads.
  4. Comments that contain links to inappropriate, irrelevant or commercial sites may be deleted.
  5. Discussion of non-scientific subjects is discouraged.
  6. No flames, profanity, ad hominem comments are allowed. This includes comments that (explicitly or implicitly) impugn the motives of others, or which otherwise try to personalize matters under discussion.
  7. We reserve the right to make spelling corrections, correct text format problems, etc.
  8. We use moderation to improve the “signal to noise” in the discussion. For this reason, we may choose to screen out comments that simply repeat points made in previous comments, make claims that have already been dealt with or that “muddy the water” by introducing erroneous, specious, or otherwise misleading assertions. These comments may be sent to “The Bore Hole“.
  9. We reserve the right to either reject comments that do not meet the above criteria, or in certain cases to edit them in a manner that brings them into accordance with our comments policy (e.g. by simply deleting inflammatory or ad hominem language from an otherwise worthy comment). In cases where we do this, it will be noted by an [edit].
  10. Given that RealClimate represents a volunteer effort by about 10 different contributors, each of whom are free to participate in queue moderation, the items indicated above only constitute the basic ground rules. We cannot insure uniform application of the various considerations listed above from one individual comment to the next.
  11. Quick responses to questions that don’t merit a full post will be placed in-line (with credits).
  12. All comments are assumed to be released into the public domain.
  13. Comments generally close after a month.
  14. Repeat violators of our comments policy (in particular, individuals demonstrating a pattern of “trolling”) may be barred from future access to the blog.

revised 01/06/11

The Surface Temperature Record and the Urban Heat Island

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There are quite a few reasons to believe that the surface temperature record – which shows a warming of approximately 0.6°-0.8°C over the last century (depending on precisely how the warming trend is defined) – is essentially uncontaminated by the effects of urban growth and the Urban Heat Island (UHI) effect. These include that the land, borehole and marine records substantially agree; and the fact that there is little difference between the long-term (1880 to 1998) rural (0.70°C/century) and full set of station temperature trends (actually less at 0.65°C/century). This and other information lead the IPCC to conclude that the UHI effect makes at most a contribution of 0.05°C to the warming observed over the past century.

[Read more…] about The Surface Temperature Record and the Urban Heat Island

Contributors

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The current contributors to content on this site are:

William Connolley was a contributor, but has now left academia; Ray Bradley, David Archer, and Ray Pierrehumbert are no longer active; Jim Bouldin was a contributor from 2009 and Caspar Ammann and Thibault de Garidel were early supporters of the site. Group posts can be assumed to be the from the whole set of current contributers, or will be individually signed.

Caspar Ammann

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Caspar Ammann is a climate scientist working at the National Center for Atmospheric Research (NCAR). Dr. Ammann is interested in the reconstruction of natural climate forcings, natural climate variability, coupled modeling of natural and anthropogenic climate change, and data/model intercomparison. Dr. Ammann got his B.S. from Gymnasium Koeniz (Switzerland), his M.S. from the University of Bern (Switzerland), and a Ph.D. from the Department of Geosciences at the University of Massachusetts.

William M. Connolley

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When I joined RC, I was a climate modeller with the British Antarctic Survey. Now I’m a software engineer for CSR. I’m still interested in communicating the science of climate change, but can no longer do so at a professional level.

I’m also elsewhere: the wikipedia project is developing into a useful resource, and my profile is User:William_M._Connolley. My personal vanity site is at www.wmconnolley.org.uk.

One of the people in the picture is me. Guess which.

ps: all my contributions online are released under the GFDL, unless I explicitly note otherwise.

Thibault de Garidel

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Dr. de Garidel received his Bachelor’s degree in Earth Sciences from the Université Lyon I, France, completed a Master in the Université Bordeaux I, France and a Ph.D. in Geosciences at CEREGE, Université Paul Cézanne (a.k.a. Aix-Marseille III).

More information about his research and publication record can be found here.

What does the lag of CO2 behind temperature in ice cores tell us about global warming? Quelle information sur le réchauffement climatique nous apportent les études qui concluent à un retard du CO2 sur la température, réalisées à partir des carottes de glace?

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This is an issue that is often misunderstood in the public sphere and media, so it is worth spending some time to explain it and clarify it. At least three careful ice core studies have shown that CO2 starts to rise about 800 years (600-1000 years) after Antarctic temperature during glacial terminations. These terminations are pronounced warming periods that mark the ends of the ice ages that happen every 100,000 years or so.

Does this prove that CO2 doesn’t cause global warming? The answer is no.
Par Jeff Severinghaus (traduit par Nicolas Caillon)

Les résultats de ces études ne sont pas toujours bien compris par le public, souvent mal restitués par les médias, et méritent donc davantage d’explications. Au moins 3 études détaillées réalisées à partir de carottes de glace montrent que le CO2 commence à augmenter autour de 800 ans (entre 600 à 1000 ans) après le démarrage de l’augmentation de température lors des terminaisons glaciaires. Ces terminaisons sont les périodes de réchauffement qui marquent la fin des périodes glaciaires et qui se produisent tous les 100 000 ans.
[Read more…] about What does the lag of CO2 behind temperature in ice cores tell us about global warming? Quelle information sur le réchauffement climatique nous apportent les études qui concluent à un retard du CO2 sur la température, réalisées à partir des carottes de glace?