RealClimate

What’s going on in the North Atlantic? « RealClimate
►http://www.realclimate.org/index.php/archives/2015/03/whats-going-on-in-the-north-atlantic

http://www.realclimate.org/images//Atlantic-Conveyor-rc.jpg

The North Atlantic between Newfoundland and Ireland is practically the only region of the world that has defied global warming and even cooled. Last winter there even was the coldest on record – while globally it was the hottest on record. Our recent study (Rahmstorf et al. 2015) attributes this to a weakening of the Gulf Stream System, which is apparently unique in the last thousand years.

The whole world is warming. The whole world? No! A region in the subpolar Atlantic has cooled over the past century – unique in the world for an area with reasonable data coverage. So what’s so special about this region between Newfoundland and Ireland?
...

http://www.realclimate.org/images//Winter15NOAA.jpg

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What are the impacts of a slowdown?

http://www.realclimate.org/images//Greenland09-59.jpg

Meltwater on the Greenland ice sheet.

The consequences of a large reduction in ocean overturning would look nothing like the Hollywood film The Day After Tomorrow. But they would not be harmless either – e.g. for sea level (Levermann et al. 2005) particularly along the US east coast (Yin et al. 2009), marine ecosystems, fisheries and possibly even storminess in Europe (Woollings et al. 2012). We have studied these consequences some years ago in an interdisciplinary project with colleagues from Bremerhaven, Hamburg and Norway – the results are summarized in Kuhlbrodt et al. 2009.

If our analysis is correct, then this indicates that climate models underestimate the weakening of the Atlantic circulation in response to global warming – probably because the flow in these models is too stable (see Hofmann and Rahmstorf 2009). Although these models predict a significant weakening for the future, they do not suggest this as early as the observations show it (see Fig. 2 of our paper). That the real flow may be more unstable than previously thought would be bad news for the future.

If the circulation weakens too much it can even completely break down – the AMOC has a well-known “tipping point” (Lenton et al., 2008).

▻https://www.youtube.com/watch?v=3niR_-Kv4SM

#climat #gulf-stream

D’après la NASA la circulation thermohaline pourrait bien être en train de s’arrêter…

http://www.washingtonpost.com/news/energy-environment/wp-content/uploads/sites/43/2015/10/201501-201509.gif

There has been growing concern, of late, that one predicted consequence of a changing climate — the slowing of the great “overturning” circulation in the Atlantic Ocean — is already starting to happen.

#changement_climatique #it_has_begun

Recent global warming trends: significant or paused or what?
▻http://www.realclimate.org/index.php/archives/2014/12/recent-global-warming-trends-significant-or-paused-or-what

http://www.realclimate.org/images//TempCP3.png

Global temperature (annual values, GISTEMP data 1880-2014) together with piecewise linear trend lines from an objective change point analysis. (Note that the value for 2014 will change slightly as it is based on Jan-Oct data only.) Graph by Niamh Cahill.

In summary: that the warming since 1998 “is not significant” is completely irrelevant. This warming is real (in all global surface temperature data sets), and it is factually wrong to claim there has been no warming since 1998. There has been further warming despite the extreme cherry pick of 1998.

What is relevant, in contrast, is that the warming since 1998 is not significantly less than the long-term warming. So while there has been a slowdown, this slowdown is not significant in the sense that it is not outside of what you expect from time to time due to year-to-year natural variability, which is always present in this time series.

Given the warm temperature of 2014, we already see the meme emerge in the media that “the warming pause is over”. That is doubly wrong – there never was a significant pause to start with, and of course a single year couldn’t tell us whether there has been a change in trend.

#climat #statistiques

New Study Finds Higher #Methane Emissions from Fracking « naked capitalism
▻http://www.nakedcapitalism.com/2013/12/new-study-finds-higher-methane-emissions-from-fracking.html

A major new study finds that methane emissions from the production of shale gas may in fact be higher than previously thought. The study, published in the Proceedings of the National Academy of Sciences [▻http://www.pnas.org/content/early/2013/11/20/1314392110.abstract] on November 25, casts into doubt the notion that natural gas produces half as much greenhouse gas pollution as coal. Natural gas has been embraced by many, including President Obama, as a centerpiece of America’s climate change plan.

Methane can be released from natural gas wells during the drilling process. Scientists have thus far had difficulty measuring these “fugitive methane emissions” precisely, with competing studies stirring controversy. The latest report, published by a group of 15 scientists, found that the U.S. Environmental Protection Agency is significantly underestimating the amount of methane released during natural gas production. Specifically, the report concludes that fugitive methane emissions could be 50% higher than EPA estimates.

(...)

If the latest figures are accurate, it could mean that the greenhouse gas advantage that natural gas has over coal could be a mirage. The Energy Information Administration estimates that U.S. carbon dioxide emissions declined 12% since 2007, citing natural gas supplanting coal as a major reason. That number does not account for methane emissions however.

#pollution #réchauffement_climatique #fracturation_hydraulique #gaz

Comment bien s’informer sur le changement climatique ? Et que penser des immenses efforts que font les climato-sceptiques pour nous convaincre que le changement climatique n’est qu’une grosse illusion ?

Voici une série de liens très riches, très informatifs sur la question, c’est un synthèse d’une des innombrables discussions passionnantes qui nourrissent la liste de « géographes critiques » (ou "criters pour les intimes...)

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Owain Jones, de l’université de l’école d’art et de sciences sociales de Northumbria a eu quelques discussions avec des climato-septiques qui l’ont beaucoup troublé... Il n’est pas du tout familier avec le sujet, mais très intéressé et cherche à consulter les documents, les informations appropriés qui lui permettraient de lui donner une idée plus précise, d’affiner sa connaissance en la matière :

Chris Gibson, professeur de géographie humaine à l’université de Wollongong en Australie recommande :

The Critical Decade: Climate science, risks and responses▻http://climatecommission.gov.au/report/the-critical-decade

John Finn, de l’université de Newport (Etats-Unis) poursuit :

Check this good book, Global Weirdness
▻https://www.randomhouse.com/book/209517/global-weirdness-by-climate-central

one of the NY Times environmental reporters was recently on Fresh Air for a very accessible 20-minute interview where he discusses climate change, but also the false equivalency bias the is so prevalent in the news media’s reporting on climate change:

▻http://www.npr.org/2013/03/21/174019103/temperature-rising-will-climate-change-bring-more-extreme-weather?ft=1&f=1007

Ilan Kelman, chercheur au Centre international de recherche climatique et environnementale (Cicero) à Oslo en Norvège propose ce site :

Explaining climate change science & rebutting global warming misinformation
▻http://www.skepticalscience.com

Joe Smith, de l’Open university explique dans un long développement :

The headline conclusion from my own work on this topic is that many of the 20-40% of the population of e.g. the US and UK who are not concerned about or not convinced by climate science findings are not driven by their assessment of the science. Rather they are positioned by prior ideological commitments (libertarianism of left or more usually right).

Many have been made suspicious by what they see as short term ’tactics’ of a climate change lobby. Personally I think that some serious mistakes have been made in the ways in which climate research and policy have been presented and in some areas practiced, and feel that more plural and dynamic accounts of that work are needed.

Below are links to a couple of blog posts that explore this question. I continue to feel that The most terrifying video you’ll ever see 2’

▻http://www.youtube.com/watch?v=AE6Kdo1AQmY

is a great resource for people who feel they are being log rolled on the science (also a nice example of what educators can do with the youtube medium). Funny and clever, and a robust argument a few years on from its production. Many millions of viewers on the basis of a well thought out argument but essentially free and (very) amateur production.

▻http://www.realclimate.org
is a good resource created by climate scientists. The hard nut contrarians mock it as campaigning. but the writers are I think all working climate scientists. Mostly US researchers I think.

▻http://www.carbonbrief.org
is more journalistic but rooted in the latest research. They make a point of fact checking key media reports. A European mostly UK bias.

►http://www.climatenewsnetwork.net
Global stories but out of the UK. Another source recently created by a group of very experienced environment/science journalists is

For more culturally informed understandings and explorations of climate change, you can hear a body of podcasts and download a book (track 11) on the subject here:
▻https://itunes.apple.com/us/itunes-u/mediating-change-culture-climate/id407470205

My posts around climate/contrarianism/knowledge politics include:

▻http://citizenjoesmith.wordpress.com/2012/02/17/dont-shoot-the-pianist-offer-a-new-tune-or-climate-scienc
argues for new approaches to public engagement and debate

▻http://citizenjoesmith.wordpress.com/2011/05/26/climate-contrarianism-is-ideological-not-hypothetical
explores the libertarian ideological foundations of many climate contrarians

▻http://citizenjoesmith.wordpress.com/2012/02/15/why-climate-change-is-different-six-elements-that-are-sha
Six elements of the new politics...

Nicholas James (Open university) répond directement à Joe Smith (Open university) :

... However It’s an amalgam of politicians [in a global context], who seem intent on denying, ignoring or in the case of UK’s Education Minister Michael Gove forcing a removal of climate change and sustainable development from the National Curriculum.

It is also a coming together but not quite ’epistemic community’ of many hundreds of scientists from sub-disciplines in the form of the IPCC trying

a) to predict and
b) to sythesise many complex findings from a wide array of sub-disciplines.

It’s not easy. The IPCC has no authority and yet its integrity is regularly questioned. Within its discourse is the view that climate change [and its causes] are natural and anthropogenic in origin. This is compelling and makes sense [scientifically?] but it too easy for decision-makers to confuse and abuse the notion of ’uncertainty’. It is intrinsic to science, it is deeply part of climate systems but it should not really be confused with doubt!

Et Joe Smith à Nicholas James :

About IPCC, politics and uncertainty: I want to argue that the IPCC should always and now be understood as a long running review process that offers a risk assessment, and the policy/politics is about risk management. For sure its a messy boundary. Mike Hulme’s Why Do We Disagree About Climate Change is a good resource on that issue, but the assessment/management distinction helps I think. Many of the contrarian commentators are focused on the science, but are really motivated by the implications of the politics. I’d agree wholeheartedly that the implied suggestion from Nick that the assessment has been rather well run (though not always well communicated), while the risk management side feels like very early days.

About getting rid of climate issues in UK govt curriculum, it is proving difficult to find out whether this is politically motivated (most assume it is and I conclude that Gove is explicitly ’’playing to imagined prejudices of a Tory right that recalls a globe half draped in the Union Jack.’). The only balancing point I have come across is Guardian journalist Leo Hickman’s argument about age appropriate learning. Former UK Govt. Climate Change Ambassador John Ashton’s reply to this is that in his experience young people seem to cope with the difficult knowledge around climate change rather better than adults. My own take on this is that, among other things, climate change is a good topic to explore why interdisciplinary perspectives are an important part of life, and geography is a good place to explore all this.

I’m aware that this list doesn’t tend to run long threads, so I’ll stay out of this one now, but anyone interested in this is welcome to get in touch.

Au tour d’Herman Douglas, géographe au Smithsonian National Museum of the American Indian à Washington :

One of the best and most entertaining presentations on the science of climate change I have heard is by Richard Alley, Evan Pugh Professor of Geosciences and Associate of the Earth and Environmental Systems Institute at The Pennsylvania State University.

I first heard him present it here at the Smithsonian last fall, at the 40th anniversary of the launching of “Limits to Growth,” where members of the Club of Rome (Dennis Meadows, Lester Brown, Jørgen Randers and others) reviewed their predictions of 40 years ago.

Alley presents a great deal of science and argues that there are eight pieces of evidence that climate change is human-induced, and that to invoke merely one of them leaves you open to criticism; but collectively they refute all arguments to the contrary.

The program and main website for the Club of Rome meeting is here:
▻http://www.si.edu/consortia/limitstogrowth2012

Richard Alley’s webcast presentation is here:
▻http://www.youtube.com/watch?v=gNxCqU9jbOM

And his powerpoint is here:
▻http://www.si.edu/Content/consortia/Richard_Alley.pdf

He says he sometimes subtitles his course:

“How to get rich AND save the planet or else.”

#climat #changement-climatique #géographie-critique #géographie #climato-sceptiques