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Some recent updates

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A couple of recent papers in Science this week relate to discussions we have had on RealClimate recently. The first by Curry and Mauritzen relates to the Gulf Stream Slowdown? post and describes the amount of fresh water that has been added to the North Atlantic over the last few decades (calculated from a database of salinity measurements) and what impact that has had on density and overturning circulations. There is a press release available at WHOI which is quite informative (hat tip to Joseph O’Sullivan for the link).

The second is related to the Storms and Climate Change post and is a perspective by Kevin Trenberth on the potential for a hurricanes and global warming link. The NCAR press release is available here.

These will undoubtedly not be the last word on the subject, and so we will probably be revisiting these topics at some point soon…

How much of the recent CO2 increase is due to human activities? L’accroissement du CO2 atmosphérique: sommes nous entièrement responsable?

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Contributed by Corinne Le Quéré, University of East Anglia.

This question keeps coming back, although we know the answer very well: all of the recent CO2 increase in the atmosphere is due to human activities, in spite of the fact that both the oceans and the land biosphere respond to global warming. There is a lot of evidence to support this statement which has been explained in a previous posting here and in a letter in Physics Today . However, the most convincing arguments for scientists (based on isotopes and oxygen decreases in the atmosphere) may be hard to understand for the general public because they require a high level of scientific knowledge. I present simpler evidence of the same statement based on ocean observations, and I explain how we know that not only part of the atmospheric CO2 increase is due to human activities, but all of it.
Corinne Le Quéré, Université d’East Anglia.

C’est une question qui revient sans cesse, bien que nous connaissions déjà la réponse : nous sommes responsable de la totalité de l’accroissement récent du CO2 atmosphérique, et ceci, malgré le fait que les océans et la biosphère terrestre répondent tous deux aux changements de réchauffement global. Les évidences les plus convaincantes pour les scientifiques (basées sur le décroissement de l’oxygène et des isotopes du carbone) ont déja été expliquées dans une page précédente disponible ici et dans une lettre à la revue spécialisée Physics Today. Cependant, ces évidences peuvent être difficiles à saisir pour les non-spécialistes car elles requièrent des connaissances scientifiques importantes. Je présente ici des évidences plus simples qui mènent aux mêmes conclusions et qui expliquent comment on sait que nous sommes responsables non seulement d’une partie de l’accroissement récent du CO2 atmosphérique, mais de la totalité.
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Gulf Stream slowdown? Est-ce que le Gulf Stream ralentit ?

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There has been an overwhelming popular demand for us to weigh in on recent reports in the Times Britain faces big chill as ocean current slows and CNN Changes in Gulf Stream could chill Europe (note the interesting shift in geographical perspective!).
par Gavin Schmidt (traduit par Pierre Allemand)

Nous avons été submergés de demandes d’évaluation des rapports récents du Times
“Britain faces big chill as ocean current slows” (la Grande Bretagne soumise à un refroidissement important en raison du ralentissement de courants océaniques) et de CNN “Changes in Gulf Stream could chill Europe” Les changement du Gulf Stream pourrait refroidir l’Europe), (notez l’intéressant glissement de perspective géographique !).

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Planetary energy imbalance?

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The recent paper in Science Express by Hansen et al (on which I am a co-author) has garnered quite a lot of press attention and has been described as the ‘smoking gun’ for anthropogenic climate change. We have discussed many of the relevant issues here before, but it may be useful to go over the arguments again here.

The key points of the paper are that: i) model simulations with 20th century forcings are able to match the surface air temperature record, ii) they also match the measured changes of ocean heat content over the last decade, iii) the implied planetary imbalance (the amount of excess energy the Earth is currently absorbing) which is roughly equal to the ocean heat uptake, is significant and growing, and iv) this implies both that there is significant heating “in the pipeline”, and that there is an important lag in the climate’s full response to changes in the forcing.

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Why looking for global warming in the oceans is a good idea Voici pourquoi rechercher le réchauffement global dans les océans est pertinent

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A lot of press and commentary came out this week concerning a presentation and press release from Tim Barnett and Scripps colleagues presenting at the AAAS meeting (The Independent, John Fleck ,(and again) David Appell…etc). Why did this get so much attention given that there is no actual paper yet?
par Gavin Schmidt (traduit par Pierre Allemand)

Un grand nombre d’articles de presse et de commentaires sont sortis cette semaine concernant une présentation et un communiqué de presse de Tim Barnett, Scripps et collègues au congrès de l’AAAS (American Society for the Advancement of Science), (The Independent, John Fleck ,(et de nouveau ici) David Appell…etc. (NdT : sites en anglais). Pourquoi cela a-t-il donné lieu à autant d’attention, alors qu’aucune publication n’est encore disponible ?

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[Read more…] about Why looking for global warming in the oceans is a good idea Voici pourquoi rechercher le réchauffement global dans les océans est pertinent