Future of the Gulf stream

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JMP
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Post by JMP »

If the study linked to below is correct, warm winds blowing across the Atlantic from the west to the east contribute more to keeping us warm than ocean currents:

http://www.oceanconserve.info/articles/ ... nkid=23052

However, I've read that those warm winds apply mostly up to about the 60. northern latitude degree and the Gulf stream is responsible for heating upwards from there. If that's true and we're losing the stream, we Scandinavians would still be freezing... and probably starving. :(
Blue Peter
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Post by Blue Peter »

There are some interesting links in the following thread on another forum:

http://www.housepricecrash.co.uk/forum/ ... opic=20048

which suggest that the data suggesting a slowdown may need some consideration. Unfortunately, I am not qualified enough to make any judgments,


Peter.
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Ballard
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Post by Ballard »

The trends show a rapid rise in temperature, a bit of local cooling may be just the thing...

http://www.statistics.gov.uk/cci/nugget.asp?id=368
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Billhook
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Post by Billhook »

A few points which may be of interest -

1/. The Arctic downwellings (which have as posted above been shutting down) are, by what I was taught a long time ago, at least as much to do with seasonal ice formation as with the cooling effect of waters going so far north.

This is because it is the water that freezes, leaving its salt dissolved in nearby water, making it that much heavier than the next inflow from the Gulf Stream, thus causing it to sink, thus providing one of the two main drivers of the NA Circulation (the other being the Westerly Gyre winds pushing surface waters back across the Atlantic.

Thus the loss of annual ice formation is by some held to be at least as relevant to the Stream's decline as the input of fresh water from net peripheral melting of the Greenland ice cap.

2/. Given that we've "smoking gun" evidence of the unnatural decline of the Gulf Stream, as well as a strong warming trend across Europe, it seems logical to say that some offsetting of the latter is already being provided by the former.

3/. If we lose the Gulf Stream entirely (with its northernmost influence reaching Spain) then the comparable coastal climates on our latitude are Southern Alaska and Labrador, where winter temps are commonly 40 degrees below, and little agriculture is feasible.

4/. I've read in NS (but haven't seen) that there are rock formations in the English Channel that show scars from the icebergs that came across and clogged it the last time the Gulf Stream shut down.

5/. If we lose it, then France gets the bulk of 60m British "economic migrants" (in current parlance).
If we don't lose it, then France gets the bulk of 40m "economic migrants" from a desicated Spain.

6/. If emigrating, don't go to France.

regards,

Bill
JMP
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Post by JMP »

Here's a discussion about what climatologists are thinking about the current situation, in the light of latest evidence: http://www.realclimate.org/index.php?p=187

A bit older discussion between climate experts on the slowdown (comment #25 looks particularly interesting):
http://www.realclimate.org/index.php?p=225

So, it seems that it is simply too early to make any definitive prognosis about the future of the stream. After gathering information about the European climate from the internet, I'm hopeful enough to assume that we probably won't see any fatal cooling (over 2 or 3 C) at least before the 2020's. In fact, most computer models that study the supposed slowdown/shutdown predict the cooling to happen much later in the century, if at all.

And as many climate scientists point out, we shouldn't forget the continuing warming by westerly winds, plus the fact that earlier shutdowns required much more freshwater input than has been predicted for this century.

Hope I'm on the right track here... otherwise, North Europe is definitively doomed. England might survive, though.
Pixie
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Post by Pixie »

JMP wrote:
And as many climate scientists point out, we shouldn't forget the continuing warming by westerly winds
But aren't the westerly winds warm because they've been passing over the Gulf Stream?
JMP
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Post by JMP »

It is claimed that warming by the atmospheric circulation over the Atlantic is not substantially dependent on ocean circulation. I'm a complete non-expert on this, so I have to refer you to my link on the top of this page, or to the following:

http://www.columbia.edu/cu/news/03/02/r ... earch.html

This scientific study on global climate change ponders the winds as well (although its interesting conclusions are not (yet) widely embraced):

http://ocean.mit.edu/~cwunsch/papersonline/doevents.pdf

However, I've noticed that when discussing the role of the winds, scientists are usually talking about mild winters in Europe, rather than warm summers, indicating that their effect might not be that relevant in summertime. What is most essential for the continuation of life in Europe are warm springs (early loss of snow covering and early rise of average temperature above 5 C, which together enable to cultivate the land) and temperate summers (enough growing time, no sudden heat drops that kill the crops). If these minimums were not met, mass starvation would be inevitable.
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Billhook
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Post by Billhook »

JMP -

further to the "loss of spring growth" scenario you outling, for the record I'd sketch the actual worst case as being:

A sudden halt to the Gulf Stream over a year or two (as has, according to the scientific record ) occured in the distant past -

plus a severe winter storm coming in bringing temperatures of -40C -

disabling our transport and security services from attempting mass evacuation southward, while also disrupting power supplies -

leading to the loss of swathes of the population to cold.


The above is a worst case, and is put here only to emphasize our present vulnerability.

regards,

Bill
JMP
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Post by JMP »

Yeah, that would be the most extreme case, with maybe 100+ million casualties. Thankfully, it's not quite likely. As mentioned, the complete shutdown of the current as happened at the end of the ice age was preceded by the melting of much larger freshwater masses than what we are facing now. More probably there might be a temporary cooling of, say, 1 to 4 centigrades, slowing the general warming. Enough to cause problems for our daily living, though.
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