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Global warming on Mars? Réchauffement global sur Mars ?

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Guest contribution by Steinn Sigurdsson.

Recently, there have been some suggestions that “global warming” has been observed on Mars (e.g. here). These are based on observations of regional change around the South Polar Cap, but seem to have been extended into a “global” change, and used by some to infer an external common mechanism for global warming on Earth and Mars (e.g. here and here). But this is incorrect reasoning and based on faulty understanding of the data.
Article invité par Steinn Sigurdsson. (traduit par Claire Rollion-Bard)

Récemment, il y a eu des suggestions qu’un “réchauffement global” a été observé sur Mars (par exemple, ici). Ceci est basé sur des observations d’un changement régional autour de la calotte polaire sud, mais semble avoir été étendu à un changement “global” et utilisé par certains pour en déduire un mécanisme commun externe pour le réchauffement global sur la Terre et sur Mars. (par exemple, ici et ici). Mais c’est un raisonnement incorrect et basé sur une mauvaise compréhension des données.
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Happy Birthday to Us

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Just recently, RealClimate topped 500,000 visits (and well over a million page views) since starting in December 2004. And by happy coincidence, a present arrives in the form of RealClimate being selected for the “Science & Technology Web Awards 2005” by Scientific American, with the citation:

A refreshing antidote to the political and economic slants that commonly color and distort news coverage of topics like the greenhouse effect, air quality, natural disasters and global warming, Real Climate is a focused, objective blog written by scientists for a brainy community that likes its climate commentary served hot. Always precise and timely, the site’s resident meteorologists, geoscientists and oceanographers sound off on all news climatalogical, from tropical glacial retreat to “doubts about the advent of spring.”

Saltier or not? Plus salé ou pas ?

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In a recent (of Sept. 16, 2005) publication in Science, Hatun et al. find that record-high salinities have been observed over the past decade in the region where water from the Atlantic flows into the northern oceans. They combine an analysis of observations with simulations using an ocean model, concluding that the salinity of the inflow to the northern oceans is controlled by ocean dynamics and the circulation in the sub-polar gyre. The observations by Hatun et al. may suggest that at the moment the warm and salty waters from the south are especially warm and salty.

In another publication paper in Science from June 17th 2005, on the other hand, Curry & Mauritzen conclude that as a whole the northern North Atlantic has become significantly fresher (less salty) in recent decades. The latter study was based entirely on observations (hydrographic data between Labrador and Europe in the past 50 years). The recent evidence for salinification provided by Hatun et al. has been interpreted by some as being inconsistent with the evidence for high-latitude North Atlantic freshening found in previous reports. So what is really happening? Is the salinity increasing or decreasing? And can the two recent Science studies be consistent with each other?

traduit de l’anglais par Claire Rollion-Bard
Dans une publication récente (du 16 Sept. 2005) dans Science, Hatun et al. ont trouvé que de fortes salinités ont été observées durant la dernière décennie dans la région où l’eau de l’Atlantique s’écoule dans les océans du Nord. Ils ont combiné une analyse des observations avec des simulations utilisant un modèle océanique, concluant que la salinité du courant vers les océans du Nord est contrôlée par la dynamique océanique et la circulation de l’enroulement sub-polaire. Les observations de Hatun et al. peuvent suggérer que les eaux chaudes et salées venant du sud sont spécialement chaudes et salées.

Dans une autre publication dans Science du 17 juin 2005, Curry & Mauritzen concluent que, dans l’ensemble, le nord de l’Atlantique Nord est devenu significativement plus doux (moins salé) au cours des récentes décennies. Cette étude était basée entièrement sur des observations (données hydrographiques entre le Labrador et l’Europe dans les derniers 50 ans). L’évidence récente pour une augmentation de la salinité fournie par Hatun et al. a été interprétée par certains comme étant inconsistante avec l’évidence de l’Atlantique Nord des hautes latitudes moins salé trouvé dans les précédentes publications. Que se passe-t’il donc réellement ? Est-ce que la salinité augmente ou baisse ? Et est-ce que les deux récentes études dans Science peuvent être compatibles l’une avec l’autre ?
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Inhofe and Crichton: Together at Last!

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Gavin Schmidt and Michael Mann

Today we witnessed a rather curious event in the US Senate. Possibly for the first time ever, a chair of a Senate committee, one Senator James Inhofe (R-Oklahoma), invited a science fiction writer to advise the committee (Environment and Public Works), on science facts–in this case, the facts behind climate change. The author in question? None other than our old friend, Michael Crichton whom we’ve had reason to mention before (see here and here). The committee’s ranking member, Senator James Jeffords (I) of Vermont, was clearly not impressed. Joining Crichton on climate change issues was William Gray of hurricane forecasting fame, Richard Benedick (a negotiator on the Montreal Protocol on ozone-depleting chemicals), and David Sandalow (Brookings Institution). As might be expected, we paid a fair bit of attention to the scientific (and not-so-scientific) points made. [Read more…] about Inhofe and Crichton: Together at Last!

Hurricanes and Global Warming – Is There a Connection? Huracanes y calentamiento global ¿Hay conexión?Ouragans et réchauffement global – existe t’il un lien ?

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by Stefan Rahmstorf, Michael Mann, Rasmus Benestad, Gavin Schmidt, and William Connolley

On Monday August 29, Hurricane Katrina ravaged New Orleans, Louisiana and Missisippi, leaving a trail of destruction in her wake. It will be some time until the full toll of this hurricane can be assessed, but the devastating human and environmental impacts are already obvious.

Katrina was the most feared of all meteorological events, a major hurricane making landfall in a highly-populated low-lying region. In the wake of this devastation, many have questioned whether global warming may have contributed to this disaster. Could New Orleans be the first major U.S. city ravaged by human-caused climate change?

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by Stefan Rahmstorf, Michael Mann, Rasmus Benestad, Gavin Schmidt, and William Connolley (traduit par Claire Rollion Bard)
Le lundi 29 août, l’ouragan Katrina a ravagé la Nouvelle-Orléans, la Louisiane et le Mississipi, laissant une traînée de destruction dans son sillage. Il va se passer du temps avant que le bilan total de cet ouragan soit estimé, mais les impacts environnementaux et humains sont déjà apparents.
Katrina était le plus craint des évènements météorologiques, un ouragan majeur laissant un terrain vide dans une région très peuplée de faible élévation. Dans le sillage de sa dévastation, beaucoup se sont demandés si le réchauffement global pouvait avoir contribué à ce désastre. La Nouvelle-Orléans pourrait-elle être la première ville majeure des Etats-Unis à être ravagée par le changement climatique causé par les humains ?
(suite…)

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[Read more…] about Hurricanes and Global Warming – Is There a Connection? Huracanes y calentamiento global ¿Hay conexión?Ouragans et réchauffement global – existe t’il un lien ?

Did the Sun hit record highs over the last few decades?

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Guest commentary by Raimund Muscheler

[note: this is a restore (8/8/05) of an article from August 3, 2005 that was accidentally deleted due to a technical glitch. Unfortunately, most of the comments could not be retrieved. We sincerely apologize to our readers!]

The solar influence on climate is a controversial topic in climate research (see previous posts here and here). The irradiance changes are assumed to be relatively small and the importance of potential amplifying mechanisms is still a matter of current debate. One reason for these uncertainties is that there are only approximately 25 years of satellite-based observations of the solar irradiance. Sunspot observations for the last 400 years clearly indicate that current levels of solar activity are very different from the state of the sun during the Maunder minimum (from approx. 1645 to 1715 AD) where almost no sunspots could be observed.
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Scientists respond to Barton

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by Gavin Schmidt and Stefan Rahmstorf

Many readers will be aware that three scientists (two of which are contributors to this site, Michael Mann and Ray Bradley) have received letters from Representative Joe Barton (Texas), Chairman of the House Energy and Commerce Committee specifically requesting information about their work on the ‘hockey stick’ papers (Mann et al (1998) and Mann et al (1999)) as well as an enormous amount of irrelevant material not connected to these studies.

Many in the scientific community would welcome any genuine interest in climate change from the committee, but the tone and content of these letters have alarmed many scientists and their professional organisations. In the words of Alan Leshner, CEO of the American Association for the Advancement of Science, the Barton letters “give the impression of a search for some basis on which to discredit these particular scientists and findings, rather than a search for understanding.” Other organisations and individual scientists have also expressed strong concerns: [Read more…] about Scientists respond to Barton

The Wall Street Journal vs. The Scientific Consensus El Wall Street Journal sobre el consenso científico en el cambio climático

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We are disappointed that the Wall Street Journal (WSJ) has chosen to yet again distort the science behind human-caused climate change and global warming in their recent editorial “Kyoto By Degrees” (6/21/05) (subscription required).

Last week, the U.S. National Academy of Sciences and 10 other leading world bodies expressed the consensus view that “there is now strong evidence that significant global warming is occurring” and that “It is likely that most of the warming in recent decades can be attributed to human activities”. And just last week, USA Today editorialized that “not only is the science in, it is also overwhelming”.

It is puzzling then that the WSJ editors could claim that “the scientific case….looks weaker all the time”.

While we resist commenting on policy matters (e.g. the relative merits of the Kyoto Protocol or the various bills before the US Senate), we will staunchly defend the science against distortions and misrepresentations, be they intentional or not. In this spirit, we respond here to the scientifically inaccurate or incorrect assertions made in the editorial.

[Read more…] about The Wall Street Journal vs. The Scientific Consensus El Wall Street Journal sobre el consenso científico en el cambio climático

New contributor

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We welcome David Archer of the University of Chicago to the RealClimate team. David adds to our expertise in ocean and carbon cycle modelling and has already contributed a guest post, with more on the way. RealClimate actively solicits contributions from the wider climate science community and so if you’d like to help out, drop us a line.

Betting on climate change

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Guest contribution by James Annan of FRCGC/JAMSTEC.

“The more unpredictable the world, the more we rely on predictions” (Steve Rivkin). The uncertainty of an unknown future imposes costs and risks on us in many areas of life. A cereal-growing farmer risks a big financial loss if the price of grain is low at harvest time, and a livestock farmer may not be able to afford to feed his herd if the price of grain goes up. One way to reduce the risk is to hedge against it in a futures market. The two farmers can enter a forward contract, for one to deliver a set quantity of grain to the other for a fixed price at a future date. And indeed farmers do routinely use futures contracts to reduce their risks.

A translation in Romanian is available here.
A Ukrainian translation is available here.
[Read more…] about Betting on climate change