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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?

 

GFS-025deg_NH-SAT1_SST_anom_24_Jan_2016

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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2015 Temperatures

Filed under: — gavin @ 21 January 2016

To no-one’s great surprise, 2015 was clearly a record year in all the surface temperature analyses (GISTEMP, NOAA, HadCRUT4, Cowtan&Way, JMA + Berkeley Earth). There is a lot of discussion of this in the press, and on the relevant websites, so not much to add here. A few figures didn’t make it into the official announcement (audio) though…

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Marvel et al (2015) Part 2: Media responses

Filed under: — gavin @ 4 January 2016

This is a second post related to the new Marvel et al (2015) paper. The first post dealing with the substantive content is here.

What with #AGU15 going on, and a little bit of overlap in content with Shindell (2014), NASA wasn’t particularly keen to put out a press release for the paper, but we did get a ‘web special‘ put out on Friday Dec 18th, the last day of AGU and a few days after the paper appeared online. I’ve been involved with many similar releases for papers and it is always a struggle to concisely say why a paper is interesting while not overselling it or being too technical (which is why only a small fraction of papers get press releases at all).

As we’ve previously remarked about other people’s press releases (eg. Stainforth et al or Willerslev et al), properly calibrating the aspect of a release that will get picked up by the media can be tricky, and so it proved in this case.

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References

  1. K. Marvel, G.A. Schmidt, R.L. Miller, and L.S. Nazarenko, "Implications for climate sensitivity from the response to individual forcings", Nature Climate Change, 2015. http://dx.doi.org/10.1038/nclimate2888

Marvel et al (2015) Part 1: Reconciling estimates of climate sensitivity

This post is related to the substantive results of the new Marvel et al (2015) study. There is a separate post on the media/blog response.

The recent paper by Kate Marvel and others (including me) in Nature Climate Change looks at the different forcings and their climate responses over the historical period in more detail than any previous modeling study. The point of the paper was to apply those results to improve calculations of climate sensitivity from the historical record and see if they can be reconciled with other estimates. But there are some broader issues as well – how scientific anomalies are dealt with and how simulation can be used to improve inferences about the real world. It also shines a spotlight on a particular feature of the IPCC process…

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References

  1. K. Marvel, G.A. Schmidt, R.L. Miller, and L.S. Nazarenko, "Implications for climate sensitivity from the response to individual forcings", Nature Climate Change, 2015. http://dx.doi.org/10.1038/nclimate2888

Unforced variations: Jan 2016

Filed under: — group @ 1 January 2016

Happy New Year, and happy new open thread.

As per usual, nuclear energy is off-topic – it’s not that it’s uninteresting, but it ends up dominating conversation to the total exclusion of everything else and just becomes repetitive and dull. Recent excursions on this topic shows what happens when we relax the moderation, so back to being strict about this. If you want to discuss this, please go somewhere else.


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