Re: Scientists discover why is the North Pole frozen

From: george of the jungle (keys_at_somewhere.not.here)
Date: 02/24/05 

Date: Thu, 24 Feb 2005 10:17:33 -1000

On 24 Feb 2005 09:34:16 -0800, "Daryl Krupa" <icycalmca@yahoo.com>
wrote:

>
>George wrote:
><snip>
>> Here is an article that disucsses the closure, and some of its
>implications (go
>> to the link to view the graphics):
>>
>> http://oceanusmag.whoi.edu/v42n2/haug.html
>
> Hmmm ... more puzzling errancy ...
>
>> How the Isthmus of Panama Put Ice in the Arctic
>>
>> By Gerald H. Haug, Geoforschungszentrum Potsdam (GFZ), Germany;
>> Ralf Tiedemann, Forschungszentrum fur Marine Geowissenschaften,
>Germany;
>> and Lloyd D. Keigwin, Woods Hole Oceanographic Institution
>
><snip>
>> In today's ocean, warm, salty surface water from the Caribbean, the
>Gulf of
>> Mexico, and the equatorial Atlantic flows northward in the Gulf
>Stream. As the
>> warm water reaches high North Atlantic latitudes, it gives up heat
>and moisture
>> to the atmosphere, leaving cold, salty, dense water that sinks to the
>ocean
>> floor. This water flows at depths, southward and beneath the Gulf
>Stream, to the
>> Southern Ocean, then through the Indian and Pacific Oceans.
>Eventually, the
>> water mixes with warmer water and returns to the Atlantic to complete
>the
>> circulation.
>>
>> The principal engine of this global circulation, often called the
>Ocean
>> Conveyor, is the difference in salt content between the Atlantic and
>Pacific
>> Oceans.
><snip>
>
> Heh? I always thought that the principal driver in
>that system was the formation of North Atlantic
>Deep Water, that is obliquely referred to above, but
>its formation is there ascribed to evaporative cooling,
>rather than the usual explanation of sinking of hyper-
>saline cold water after the surface layer freezes.
> But Haug, etc. want to blame it all on wind, and
>differential salinity in the Pacific and Atlantic.
>

There is a French web site - Mercator Ocean that has high resolution
maps of the North Atlantic. The formation of deep water looks more
complicated than most models would have it. The hypersaline freezing
model has the problem of fresh water layering in the Arctic. The
Arctic water is typically much fresher than the North Atlantic water
because the input of rivers in the Arctic so ice formation mostly does
not make Arctic surface water sink to the bottom. Cooling of salty
Atlantic water by cold Arctic air creates dense water that sinks.

There are other problems with the various models of the THC but
there's not enough time to go further.

>> Revving up the Gulf Stream
>> How does this make ice in the North?
><snip>
>> An invigorated Ocean Conveyor could
>> have driven a stronger flow of deep waters from the Atlantic to the
>North
>> Pacific Ocean, which is the end of the line for deep-ocean
>circulation.
>
> I have serious problems with their global current diagram,
>which would make the Califormia Current the product of upwelling, and
>ignores the formation of Deep Water
>in the Antarctic.
>
Hmmm...I thought the upwelling was a product of the current.

><snip>
>> In the Subarctic Pacific, these deep waters could
>> have upwelled, rising to the sunlit surface to provide the
>ingredients to spark
>> enormous blooms of phytoplankton.
><snip>
>
> Ah, so the diagram is not for present conditions,
>but rather for an imaginary set of conditions in the
>Late Pliocene.
> Interesting ... but not very well-labelled.
>
>
>> Short-circuiting the Conveyor
><snip>
>
>> The onset of Northern Hemisphere glaciation also affected the
>Subarctic Pacific.
>> It led to the formation about 2.7 million years ago of a freshwater
>lid at the
>> surface of the ocean, called a halocline.
>

It's really hard to get a halocline where the water is upwelling,
which I thought they wrote the NPac was doing.

> What? Now the freshening of the North Pacific
>is an effect, not a cause, of Northern Hemisphere
>Glaciation?
> This conflicts directly with Haug's article in _Nature_.
> I don't get it.
>
>

I'm not sure any of them get it. None of these folks seem to get the
basic thermodynamics of the THC. I need to take a better look at the
articles because what I have seen here doesn't make much sense.

><snip>
>> The lessons from these vast geologic and geographic changes is both
>elegantly
>> simple and excruciatingly complex. The opening and closing of seaways
>has a
>> profound influence on the distribution of fresh water, nutrients, and
>energy in
>> the global ocean. The coupling of these changing oceans with a
>changing
>> atmosphere inevitably means a changing climate.
><snip>
>
> But does not, apparently, mean a frozen North Pole.
>
>Still confused,
>Daryl Krupa

I'm still confused too. I think that the confusion reflects the
inadequacies of the models & explanations provided by the authors.

_george

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