Newsgroups: comp.arch
Subject: Re: Hooking processors together
From: Norman Yarvin <norman.yarvin@snet.net>
Message-ID: <hImdnXLvBpV0LNzVnZ2dnUVZ_rvinZ2d@giganews.com>
Date: Sat, 31 May 2008 15:15:37 -0500

In article <0sKdna1LyPq00N3VnZ2dnUVZ8q2dnZ2d@giganews.com>,
Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:

>What I believe is that it is perfectly possible for the next
>Scandinavian Ice Age to occur as a result of Global warming, due to
>polar ice melting, thereby diluting the salt surface water making it not
>heavy enough to sink and drive the subsurface current back south:
>
>The result of something like this would be to (temporarily?) stop the
>Gulf stream and giving Norway the climate it's latitude should indicate,
>i.e. Siberia/northern Alaska.

That's a popular notion, but not likely.  Your prevailing winds will come
from over the ocean at any rate, so you'll have a 'maritime climate',
with much less seasonal variation than is found in the middle of
continents, no matter what happens to the Gulf Stream.  For details, see
the writeup at:

http://64.233.169.104/search?q=cache:axAQupyb5fkJ:www.americanscientist.org/template/AssetDetail/assetid/51963%3Ffulltext%3Dtrue%26print%3Dyes

which is Google's cache of an article which is down at the moment:

http://www.americanscientist.org/template/AssetDetail/assetid/51963?fulltext=true&print=yes

The full text of the scientific journal article on which it is based can
be found at the home page of one of the authors:

http://www.atmos.washington.edu/~david/Gulf.pdf

They do, of course, make use of computer modeling in getting those
results, but the computer models are being used in a regime where they
should be fairly reliable -- that is, the modeling of large-scale
airflows, which are well-resolved.  (This is in contrast to the usage of
such models in predicting global warming, in which much depends on the
details of clouds and such, which the models don't have enough resolution
to capture.)


--
Norman Yarvin						http://yarchive.net

Newsgroups: comp.arch
Subject: Re: Hooking processors together
From: Norman Yarvin <norman.yarvin@snet.net>
Message-ID: <wf2dnZ8-u7JSd9_VnZ2dnUVZ_u6dnZ2d@giganews.com>
Date: Sun, 01 Jun 2008 13:30:39 -0500

In article <L5KdnWawHOfi2d_VnZ2dnUVZ8uKdnZ2d@giganews.com>,
Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:
>Norman Yarvin wrote:
>> In article <0sKdna1LyPq00N3VnZ2dnUVZ8q2dnZ2d@giganews.com>,
>> Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:
>>> The result of something like this would be to (temporarily?) stop the
>>> Gulf stream and giving Norway the climate it's latitude should indicate,
>>> i.e. Siberia/northern Alaska.
>>
>> That's a popular notion, but not likely.  Your prevailing winds will come
>> from over the ocean at any rate, so you'll have a 'maritime climate',
>> with much less seasonal variation than is found in the middle of
>> continents, no matter what happens to the Gulf Stream.  For details, see
>> the writeup at:
>
>Oh, I do agree!
>
>The only place in Norway with anything approaching real inland climate
>would be Finnmarksvidda, i.e. the mountain plateau in the central part
>of northern Norway, and even there this only occurs under long stable
>cold spells, with little or no wind from the coast.
>
>Most of Norway would be like the coastal areas of Alaska, Oslo is about
>the same latitude as Anchorage.

Alaska doesn't have the large stretch of water that you have protecting
you; winds can blow across from Siberia without being much heated by the
intervening water (which freezes over in winter anyway, mostly removing
its ability to heat the air).  And that is the way the prevailing winds
blow; there is not the feature you have, of them coming somewhat up from
the south as well as from the west.

Farther down the coast, in coastal areas which are behind a much larger
stretch of water, the weather is a lot like Europe's; Seattle's rains are
as oppressive as Britain's.


--
Norman Yarvin						http://yarchive.net

Newsgroups: comp.arch
Subject: Re: Hooking processors together
From: Norman Yarvin <norman.yarvin@snet.net>
Message-ID: <RrmdnXSjpK6ReN_VnZ2dnUVZ_tDinZ2d@giganews.com>
Date: Sun, 01 Jun 2008 13:06:04 -0500

In article <g1tp46$bvc$1@gemini.csx.cam.ac.uk>,
Nick Maclaren <nmm1@cus.cam.ac.uk> wrote:

>In article <hImdnXLvBpV0LNzVnZ2dnUVZ_rvinZ2d@giganews.com>,
>Norman Yarvin <norman.yarvin@snet.net> writes:
>|> In article <0sKdna1LyPq00N3VnZ2dnUVZ8q2dnZ2d@giganews.com>,
>|> Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:
>|>
>|> >The result of something like this would be to (temporarily?) stop the
>|> >Gulf stream and giving Norway the climate it's latitude should indicate,
>|> >i.e. Siberia/northern Alaska.
>|>
>|> That's a popular notion, but not likely.  Your prevailing winds will come
>|> from over the ocean at any rate, so you'll have a 'maritime climate',
>|> with much less seasonal variation than is found in the middle of
>|> continents, no matter what happens to the Gulf Stream.  For details, see
>|> the writeup at:
>
>Actually, no.  Yes, it would probably remain maritime (unless the air
>currents changed, which doesn't seem likely), but we are talking about
>a temperature drop of up to 10 Celsius.  The previous flip was a rise
>of 9 degrees Celsius in under 50 years.

Have a look at the articles I referenced, which seriously challenge that
idea.  It's not just a matter of the air coming over the ocean.  Ocean
currents themselves are mostly driven by the prevailing winds.  The
prevailing winds across the Atlantic are somewhat northerly in direction
(in addition to the general west-to-east flow of air that prevails at
those latitudes).  This brings warm air (and under it, water) to Europe.
The northerly aspect of the flow is generated largely by the Rocky
Mountains, which aren't going away any time soon; they force a general
southerly flow of air above the US, which then rebounds over the
Atlantic.

As for the "earlier flip", I presume that's a reference to the Younger
Dryas; the informal article I referenced doesn't disagree that there were
dramatic changes in climate then, but says that some other cause should
be found, since a shutdown of the Gulf Stream doesn't nearly suffice.

This research isn't any sort of drastic revisionism; in the informal
article, the author concludes with a rather weary:

	"When Battisti and I had finished our study of the influence of
	the Gulf Stream, we were left with a certain sense of deflation:
	Pretty much everything we had found could have been concluded on
	the basis of results that were already available."


--
Norman Yarvin						http://yarchive.net

Newsgroups: comp.arch
Subject: Re: Hooking processors together
From: Norman Yarvin <norman.yarvin@snet.net>
Message-ID: <f_GdnRdpjs3W39nVnZ2dnUVZ_vOdnZ2d@giganews.com>
Date: Mon, 02 Jun 2008 13:56:11 -0500

In article <Ur6dnT8uFs9xEN7VnZ2dnUVZ8vydnZ2d@giganews.com>,
Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:
>Point taken though: It should be somewhat harder for an ice age to
>totally cover Norway, except that is has happened several/many times
>during the last million years, and the last was only 10k years ago.

Yeah, if the ocean gets thoroughly covered with ice, you can say goodbye
to your maritime climate; ice is a good insulator.  That's not likely to
happen as part of global warming, but as a general threat it is worth
paying attention to.

Looking a bit further, I see that the main authors of the study I
referenced earlier have written a book chapter which delves into the
issue of "abrupt climate change" in the North Atlantic:

        2007 Seager, R. and D.S. Battisti: Challenges to our
	understanding of the general circulation: abrupt climate change.
	In "Global Circulation of the Atmosphere" (eds. Schneider and
	Sobel). Pg, 331-71, Princeton University Press.

        http://www.atmos.washington.edu/~david/seager_battisti_final.pdf

I haven't finished reading it, but they seem to be building up to
invoking large amounts of sea ice:

	"The most common explanation for how winters around the North
	Atlantic could become so severe is that sea ice expanded
	southward to the latitude of southern Britain.  If winters around
	the North Atlantic got as cold as the reconstructions suggest
	they did during stadials and the Younger Dryas then sea ice would
	almost certainly encroach this far.  How this could ever happen
	is a subject we will shortly turn to."

In any case, it's good reading: not as jargon-filled as the formal paper
I referenced earlier, nor as lightweight as the popular article.


--
Norman Yarvin						http://yarchive.net

Newsgroups: comp.arch
Subject: Re: Hooking processors together
From: Norman Yarvin <norman.yarvin@snet.net>
Message-ID: <DNWdnS5imMTCOtjVnZ2dnUVZ_sninZ2d@giganews.com>
Date: Tue, 03 Jun 2008 15:19:43 -0500

In article <f9mdnVH32bnyeNnV4p2dnAA@giganews.com>,
Terje Mathisen  <terje.mathisen@hda.hydro.com> wrote:
>Norman Yarvin wrote:
>>         http://www.atmos.washington.edu/~david/seager_battisti_final.pdf
>
>Wow!
>
>This report contains the most amazing evidence I have ever seen for the
>connection between Greenland/Scandinavia ice ages and the Gulf stream:
>
>(I've extracted a copy of the figure and put it on my server)
>
>	http://tmsw.no/images/climate.jpg
>
>"Figure 2.2 Reconstructed sea surface temperatures based on alkenone
>unsaturation ratios in sediments on the Bermuda Rise for the period from
>30,000 to 60,000 years ago (line with dots, left axis), plotted together
>with Greenland 18-O (plain line, right axis) on the GISP2 ice core time
>scale. Taken from Sachs and Lehman (1999)."
>
>Even when you allow for the fact that the time scale for the sediments
>aren't locked down, so they have adjusted it for maximum fit to the
>Greenland values, the correlation is still so strong that the connection
>is proven "beyond all reasonable doubt", at least to me.

There's definitely a very strong correlation there; but it doesn't do
much to establish causes: it just indicates that when Greenland warmed
and cooled, so did the sea at Bermuda (and points upstream of Bermuda,
where the sediments came from).  A lot of things can cause simultaneous
warming and cooling.  If you're looking for the effects of shutdown of
the Gulf Stream, you might even look for *gaps* in such correlations,
where southerly points warmed while northerly points cooled, due to a
reduction of heat transfer from south to north.


--
Norman Yarvin						http://yarchive.net