Talk:Shutdown of thermohaline circulation

message: I rolled back  Abe Froman; apologies for not doing it via normal means. Anyway - I thought that Europe is not cooling is pretty well known and barely needs support from a ref. But  would do if you want one William M. Connolley 21:46, 13 October 2006 (UTC)
thread_title: 2008

message: This article says that the shutdown of thermohaline circulation would not affect the climate in Europe greatly, yet the majority of the references state otherwise. That was my general impression of the article; and the view of general unimportance of THC is not a commonly held one. -Iopq 12:01, 28 November 2006 (UTC)
replies: text: The article doesn't say that. It does say that shutdown of the THC is considered unlikely. I'm not sure what you mean by "maj of refs" William M. Connolley 13:20, 28 November 2006 (UTC)
replies: text:  The article keeps changing pretty quickly. My comment is no longer valid as of this revision. -Iopq 12:07, 13 December 2006 (UTC)

text: The theory is for the major changes to affect N Europe mostly William M. Connolley 13:01, 21 January 2007 (UTC)

text: If it were on the way to slowing down you would expect to see soomething William M. Connolley 08:25, 10 July 2007 (UTC)
thread_title:  Bias 

message: Just thought I'd answer the question in the edit history, in the forementioned article it talks that shutdown of the THC is unlikely to have been a result of Global Warming and that the Bryden measurements picked up a short term variability. If that is what 198.151.13.8 was on about. AlexD 17:56, 11 September 2007 (UTC)
thread_title: Nature, vol. 448, pp844

message: Given that this is a multidisciplinary subject, I'd like to know what is meant by "abrupt' in this context. It means very different things for geologists and meteorologists for example.
It would seem obvious that the flows cannot be stopped like turning off a light switch, but it would have to be much, much slower. There's simply too much energy stored in the moving mass of water.
Stopping it suddenly (in days or weeks?) would involve dissipating that energy somehow, and it would be most likely (if it could be done at all,) to result in major meteorological events.
But what time-table could it be stopped? This would seem to be a very important question to ask before trying to decide if it was likely or not.
Wizodd (talk) 13:20, 3 August 2008 (UTC)
replies: text: A fair point. "abrupt" does get thrown at funding agencies and the public and perhaps even journal papers, but means rather little. Maybe 10 years, would be my best guess, but without a meaningful external definition (try IPCC perhaps?) that doesn't help much. Woods Hole is suitably vague  but does contain the word "decade" William M. Connolley (talk) 22:13, 3 August 2008 (UTC)
thread_title:  Terms definition 

message: Just how good are the predictions for freshwater increases?
With the massive decline in the average age of Arctic sea ice, has the salinity of the Arctic Ocean surface waters decreased?
The rapid freeze last fall suggests that the salinity is much lower than typically observed, and, of course, young ice is thinner and weaker and melts more easily.
There is also the question of the Greenland ice melt. The question being, how fast CAN the ice end up in the ocean?
The fastest glacier in the world, the Jakobshavn glacier in Greenland, which is currently moving at a rate in excess of 100 m/year, is already moving one order of magnitude faster than we previously thought possible. How fast CAN the ice move?
The mechanisms which power this process are all positive feedback--they accelerate with time.
A fast moving glacier develops more crevices across the direction of flow, which permit more melt water from the surface of the glacier to penetrate to the bottom of the ice, more liquid water under the ice accelerates the glacier.
The fastest avalanche clocked (Mt. St. Helens, 1982) moved at over 250mph. Of course, fast avalanches are, so far as I know, always supported on a layer of air/steam, so a glacier would not normally move nearly as fast, but a well-lubricated ice/rock junction will have minimal friction, so I suspect that it is possible for a glacier to move substantially faster than Jakobshavn glacier is moving today.
Such movements on a larger scale could conceivably move a great deal of fresh water into the sea in a very short time (days to weeks.)
Has anyone modeled this? Because it will apply to the Antarctic East Ice Sheet movement too, and THAT could conceivably dump hundreds of cubic km into the sea in a short time if it were lubricated.
Wizodd (talk) 17:15, 5 August 2008 (UTC)
thread_title:  Are freshwater estimates accurate? 

message: So far as I've been able to find, many of the climate simulation models agree that a shutdown is possible, and yet the seeming consensus is that it is "extremely unlikely."
This would seem to show a lack of confidence in the models, but these same models are consulted and used to support many other factors and results of climate change.
What justifications are there for declaring this "extremely unlikely?"
Wizodd (talk) 17:21, 5 August 2008 (UTC)
replies: text: I don't understand you. None of the GCMs show a shutdown. What are you referring to? William M. Connolley (talk) 20:45, 5 August 2008 (UTC)
thread_title:  Confusion about reasons for delaring the event "extremely unlikely" 

message: These are some of the issues I had with this section.  Apologies if the structure and prose are not up to scratch, but I think that you will be able to follow some of the issues from the below.  
    * The results are a surprise to scientists in the field.
> This is nice.  Why are the results a surprise?  One would prefer an academic, professional (or, better yet - but perhaps a luxury) and objective reason for why they are so surprised.    
    * Modelling suggests that increase of fresh water flows large enough to shut down the thermohaline circulation would be an order of magnitude greater than currently estimated to be occurring, and such increases are unlikely to become critical within the next hundred years; this is hard to reconcile with the Bryden measurements.
>Aside from mathematics, doesn't experimental verification take precedence over modelling?  Besides, which models are being referred to?  Have any of those models stood up to non-trivial scientific cross analysis (ie: do they predict likely future outcomes?).  
    * The Bryden results could be caused by natural variation, or "noise", that is, coincidence.  
>Are there not statistical methods which the Bryden paper has been put through in order to reduce the effects of noise in the results?  I imagine that this is likely (or, at least, that upon placing their raw numerical results online - someone would be able to do it)
> There exist robust statistical methods for determining the probability that the results could be generated by random measurement noise or otherwise - what might those statistical methods say about the likelihood of current experimental evidence 'fluking' a trend?  The statements as it stands is woolly (ie: subjective and not scientific).  
    * If the results are correct, perhaps thermohaline circulation reductions will not have the drastic effects that have been predicted on European cooling.
> Is this POV pushing?  There are not enough references for such a broad sweeping statement to be made.  A less POV pushing way of making the statement would be to say that ....."if there were a larged body of evidence indicating x, y and z, then it would be more reasonable to make the assertions X,Y and Z".  Even then, I think most people would push you towards explaining WHY x,y and z would imply X, Y and Z.  
    * While previous shutdowns (e.g. the Younger Dryas) have caused cooling, the current overall climate is different; in particular sea-ice formation is less because of overall global warming.
    * However, a thermohaline circulation shutdown could have other major consequences apart from cooling of Europe, such as an increase in major floods and storms, a collapse of plankton stocks, warming or rainfall changes in the tropics or Alaska and Antarctica (including those from intensified El Niño effect), more frequent and intense El Niño events, or an oceanic anoxic event (oxygen (O2) below surface levels of the stagnant oceans becomes completely depleted - a probable cause of past mass extinction events).
Further measurements support the interpretation of natural variation.[16] 
> I WISH to reple the [16] with a  tag as the referred to paper is not open to full public viewing (unless you would like to argue this point).
ConcernedScientist (talk) 08:14, 19 March 2009 (UTC)
replies: text: errm, taking your last point first, are you under the impression that Nature isn't a WP:RS? Because I can assure you that it is William M. Connolley (talk) 20:49, 19 March 2009 (UTC)
thread_title: Point by Point Criticism of  Bryden measurements reported late 2005 Section 

message: Dansgaard-Oeschger events and the Younger Dryas event are not caused by the shutting down of thermohaline circulation; the shutdown is merely an effect of them, their cause being changes in atmospheric circulation regimes.  According to Seager, "Only through an inflated view of the impact of ocean circulation could it be thought that the enormous glacial era abrupt changes were caused by changes in ocean circulation. Instead, as we have argued, changes in atmospheric circulation regimes had to be the driver, see (Seager and Battisti,2006)."  See http://www.ldeo.columbia.edu/res/div/ocp/gs/ for the author's explanation. Gf1605 (talk) 01:03, 6 November 2009 (UTC)
replies: text: That is certainly Seagers opinion William M. Connolley (talk) 10:47, 6 November 2009 (UTC)
thread_title:  Thermohaline circulation's atmospheric warming effect is insignificant 

message: When did the recent interruption of the transatlantic stream end? The article only says it lasted "briefly". Did temperatures in Europe rise again after it was restored?--87.162.41.11 (talk) 12:06, 17 February 2010 (UTC)
thread_title:  Jan 2010 

message: More evidence from http://www.nature.com/nclimate/journal/v5/n5/full/nclimate2554.html Reported also at http://www.washingtonpost.com/news/energy-environment/wp/2015/09/24/why-some-scientists-are-worried-about-a-surprisingly-cold-blob-in-the-north-atlantic-ocean/  — Preceding unsigned comment added by 188.103.186.104 (talk) 07:37, 26 September 2015 (UTC)
thread_title:  July 2014 

message: Doesn't The Day After Tomorrow climate fiction-disaster film uses this scenario? If that is, the article could mention it.  — Preceding unsigned comment added by Gajatko (talk • contribs) 20:42, 26 September 2014 (UTC)
replies: text: Done. prokaryotes (talk) 16:19, 23 January 2016 (UTC)
thread_title:  Movie Reference 

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thread_title:  External links modified (January 2018) 

message: I have started a discussion about merging this article into Atlantic Meridional Overturning Circulation. See here. My point was "I have the feeling that they overlap a lot and that a merger might reduce the amount of work needed to keep them both up to date?" Reply there by User:Femkemilene was "I think the articles as currently organised should be merged. Both cite a lot of medium-old studies (2017 and before), while this is a subject of intense study. Another example where our limited resources are the main reason I'd support a merge to ensure old material is deleted and stays deleted.". I'll add the merger tags now and wait a week for reactions. EMsmile (talk) 18:53, 28 March 2022 (UTC)
replies: text: you're very good at mergers. What is your view? Can we regard this as closed and do the merger? EMsmile (talk) 09:08, 12 April 2022 (UTC)
thread_title:  Merge to [[Atlantic Meridional Overturning Circulation]]