[Lowfer] Global cooling or warming???

[Eric Smith]

My question to global warming enthusiasts is always: what is the
Earth's ideal temperature?

On 1/12/10, Chris Trask <christrask at earthlink.net> wrote:
>>
>> How does the Great Conveyor Belt fit into this?
>>
>
>     A significant input to the conveyor is the "chimneys" in the North
> Atlantic, where less salty, colder water moving southward merges with
> saltier, warmer water flowing northward in the surface layers.  When these
> two water masses converge, they reach a point where the density of the water
> (due to temperature and salinity) will cause it to flow vertically downward
> in the form of "convective chimneys", where it then flows southward along
> the ocean floor.  This phenomenon is known as the "Atlantic meridional
> overturning circulation" (AMOC) and is a form of thermohaline circulation
> (THC).  It's a forcing vector that keeps the conveyor flowing.
>
>     There are two significant changes that have been taking place, the most
> obvious one being the melting of the northern latitude ice.  This makes the
> water moving southward less salty, which makes it flow more readily over the
> warmer water moving northward.  At the same time, the water moving northward
> is warmer, so as it passes through the subtropics and tropics there is more
> evasporation, making the water saltier.  These two vectors were supposedly
> going to cause the AMOC region to move southward, eventually causing the
> climate in Britain and other areas to resemble Siberia, in a scenario known
> as "Sudden Climate Change".  A similar event took place in the northern
> hemisphere about 8,000 years ago when a large freshwater lake over northern
> Canada suddenly emptied into the Arctic Ocean as the ice sheet was
> retreating.
>
>     However, there is another form of sudden climate change that is
> appearing to be more likely.  In time, the amount of northern latitude ice
> will diminish, and the southward flow of colder, lighter water into the AMOC
> region will become warmer and saltier.  Additionally, with the polar ice cap
> greatly reduced the Arctic Ocean water will become warmer by way of solar
> absorption.  At the same time, the denser and warmer northward flow will
> become increasingly warmer and saltier, and the result will be a rapid
> northward shift of the AMOC region.  You can imagine what will happen then.
>
>     Either way, what has been happening is that the number of these
> convective chimneys has greatly diminished.  In the early 60s, there were as
> many as 13 regions along the belt where this was taking place.  At last
> count, there were two.  The British researcher Peter Wadhams has been
> keeping track of these for decades:
>
>     http://en.wikipedia.org/wiki/Shutdown_of_thermohaline_circulation
>
>     A book well worth reading is "The Two-Mile Time Machine" by Richard
> Alley.  He's a strong proponent of the sudden cooling scenario, and among
> other things he discusses the three known forms of solar forcing that have
> 100,000, 40,000, and 19,000 year cycles.
>
>     An aspect of this trend that was interesting to watch this past summer
> was a significant cooling of the surface of the Northern Pacific, generally
> known as a "sea surface temperature anomally".  This has some odd effects to
> the Eastern Pacific hurricane season, in particular the spectacular end of
> hurricane Jimena.  A category 4 storm, Jimena was initially forecast to pass
> into central Arizona and dump 4-8" of rain into the lower desert, which
> would have been a disaster due to flooding.  Instead, it ran head-on into a
> strong cold front which stopped it dead in its tracks and then ripped it
> apart, in what one NHC forecaster called a "textbook case of shearing".  A
> later category 5 storm met a similar but less spactacular end.  The colder
> Northern Pacific provided the strong shearing winds that put the kabosh on
> the Atlantic hurricane season.
>
>     And if you think all this is interesting, just wait until this next
> cutoff low sweeps deeply into northern Mexico and then along the Gulf Coast.
> It's getting pretty wierd out there.
>
> Chris Trask
> N7ZWY
> WDX3HLB
> Senior Member IEEE
> http://www.home.earthlink.net/~christrask/
>
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