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Blizzard Jonas and the slowdown of the Gulf Stream System

Filed under: — stefan @ 24 January 2016

Blizzard Jonas on the US east coast has just shattered snowfall records. Both weather forecasters and climate experts have linked the high snowfall amounts to the exceptionally warm sea surface temperatures off the east coast. In this post I will examine a related question: why are sea surface temperatures so high there, as shown in the snapshot from Climate Reanalyzer below?



I will argue that this warmth (as well as the cold blob in the subpolar Atlantic) is partly due to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), sometimes referred to as the Gulf Stream System, in response to global warming. There are two points to this argument:

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Noise on the Telegraph

Filed under: — rasmus @ 11 February 2015

I was surprised by the shrill headlines from a British newspaper with the old fashioned name the Telegraph: “The fiddling with temperature data is the biggest science scandal ever”. So what is this all about?

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The answer is blowing in the wind: The warming went into the deep end

There has been an unusual surge of interest in the climate sensitivity based on the last decade’s worth of temperature measurements, and a lengthy story in the Economist tries to argue that the climate sensitivity may be lower than previously estimated. I think its conclusion is somewhat misguided because it missed some important pieces of information (also see skepticalscience’s take on this story here).

The ocean heat content and the global mean sea level height have marched on.

While the Economist referred to some unpublished work, it missed a new paper by Balmaseda et al. (2013) which provides a more in-depth insight. Balmaseda et al suggest that the recent years may not have much effect on the climate sensitivity after all, and according to their analysis, it is the winds blowing over the oceans that may be responsible for the ‘slow-down’ presented in the Economist.

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  1. M.A. Balmaseda, K.E. Trenberth, and E. Källén, "Distinctive climate signals in reanalysis of global ocean heat content", Geophys. Res. Lett., vol. 40, pp. 1754-1759, 2013.

Ice hockey

Eric Steig

It is well known that ice shelves on the Antarctic Peninsula have collapsed on several occasions in the last couple of decades, that ice shelves in West Antarctica are thinning rapidly, and that the large outlet glaciers that drain the West Antarctic ice sheet (WAIS) are accelerating. The rapid drainage of the WAIS into the ocean is a major contributor to sea level rise (around 10% of the total, at the moment).

All of these observations match the response, predicted in the late 1970s by glaciologist John Mercer, of the Antarctic to anthropogenic global warming. As such, they are frequently taken as harbingers of greater future sea level rise to come. Are they?

Two papers published this week in Nature Geoscience provide new information that helps to address this question. One of the studies (led by me) says “probably”, while another (Abram et al.) gives a more definitive “yes”. More »

Times Atlas map of Greenland to be corrected

We were pleased to hear from the University of Arizona’s Jeff Kargel that the Times Atlas folks are now updating their atlas of Greenland. As we reported earlier, the first edition was completely in error, and led to some rather bizarre claims about the amount of ice loss in Greenland. Kargel reports that HarperCollins (publisher of the Times Atlas) has now fully retracted their error and has produced a new map of Greenland that will be made available as a large-format, 2-side map insert for the Atlas and will also be available free online. Meanwhile, Kargel and colleagues have produced their own updated small-scale map and have written a paper that includes both their new map and a description of the incident that led up to it. Kargel was instrumental in pushing the cryosphere community to send a strong message to the publishers that they needed to correct their mistake. (A pre-print of the paper, currently under review and under public discussion on Cryolist, is available here.)

Figure 1 in Kargel et al. (2011) generated by a collaboration of the Geological Survey of Denmark and Greenland (GEUS) and the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) with the Polar Geospatial Center Department of Geology and Geophysics, University of Minnesota. Contact: Michele Citterio (GEUS) for questions about the glacier outlines or Paul Morin (UMinn.) for questions about the MODIS base image mosaic.

HarperCollins is to be commended for listening to the scientific community and producing a corrected map. Unfortunately, and despite recent events demonstrating that popular allegations against climate scientists are all wrong, HarperCollins still says on their web site that it’s all the scientists’ fault for not being clear (“The one thing that is very apparent is that there is no clarity in the scientific and cartographic community on this issue”,they write). Hmm. Our own view is that anyone flying over Greenland en route to Europe from North America would instantly have recognized a problem with the Times Atlas (assuming they knew their location of course). As Kargel and colleagues write in their paper:

“Distinguishing manifest, ignorable nonsense from falsehoods that might take root in the public mind is difficult, but the magnitude of and apparent authority behind this particular mistake seemed to warrant a rapid and firm response. The eventually constructive reaction of HarperCollins, which not only withdrew its mistaken claim but also produced a new map to be included in the Times Atlas as an insert, shows the value of such a response. No less than grotesque trivialization, grotesque exaggeration of the pace or consequences of climate change needs to be countered energetically.”

Nevertheless, they caution that “scientists cannot possibly challenge all of the innumerable misunderstandings and misrepresentations of their work in public discourse.”

Well said. Of course, many scientists can do more, and we encourage all of our colleagues to speak publically about their research and, as the international glaciological research community did in this case, to try to correct misconceptions. At the same time, hopefully, HarperCollins will catch on and recognize that being scientifically literate is not just scientists’ responsibility, but is everyone’s responsibility.

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