Global Warming was Rain Fall
Mon, 09 Jan 2006 06:18:32 PST
In a message dated 1/7/2006 8:09:51 PM Pacific Standard Time, writes:
I wonder how much the change in the magnetic poles has to do with our climate 
changes as well?
It certainly can affect global weather patterns, as can a whole range of 
other phenomena!  I recently watched a History channel special: The Big Chill: the 
Little Ice Age.  For some 500 years in the Middle Ages, Europe (and much of 
the Northern Hemisphere) experienced a period of very cold weather.  While 
there is disagreement about what caused this -- a period of unusually high 
volcanic activity or major changes in the warm water conveyor in the Atlantic Ocean 
-- there is no disagreement about the effect.  The changes this caused in 
agriculture, living standards, war, migration, (even some speculation about why 
Stradivarius violins are the way they are -- formed of harder, denser wood grown 
in a cold climate), etc., was fascinating to hear and see.  What is important 
is that it seemed to have occurred suddenly and very rapidly (although a mere 
blink in geologic time, of course!).  Wine grapes, for example, (introduced by 
the Romans) were common in England prior to the Little Ice Age and produced 
the major beverage of the time -- wine.  The extreme cold killed them off 
causing a major change from wine drinking to beer and hard alcoholic beverages, 
etc., that could be created from more cold tolerant cereal crops.  Cereal crops, 
the mainstay of the population, were ultimately devastated by both the Little 
Ice Age and almost continuous warfare.  One result was that the heretofore 
scorned potato became a major food crop because it grew underground protected 
from weather extremes, as well as being somewhat difficult to destroy/burn by 
marauding armies.  The thriving Viking civilization in Greenland disappeared when 
the climate became too cold for agriculture and grazing animals.  Heavy sea 
ice stopped shipping to and from Greenland and Europe, cutting off resupply of 
those colonies causing their extinction.  One theory is that of the 400K man 
army Napoleon used to invade Russia, barely 1% survived to return to France 
having been decimated by an unusually cold period of weather -- much of it either 
starved or froze to death, or both.  Excavations for a building in Vilnius, 
Lithuania, uncovered a mass grave of some 3000 Napoleonic troops that died 
there.  How many others never got buried or lie in still uncovered mass graves?

The most fascinating theory concerned the warm water conveyor that carries 
warm tropical waters northward (warming the whole region of the North Atlantic) 
that gradually cools, increasing in density.  This colder, denser salty water 
sinks at the North end of the conveyor, gradually working its way back to the 
equator only to rise (to replace the warm water moving northward) again to 
keep the "engine" of this current functioning.  The theory is that the warmer 
period prior to the Little Ice Age caused substantial melting of the polar ice 
caps.  The resulting flood of fresh water, lighter than salt water, mixed with 
the saline water on the surface of the ocean, so diluting it that it ceased its 
former increase in density to the point where it no longer sank to create the 
southward flow of cold water to the equator to be warmed effectively ceasing 
the conveyor.

There is a great deal of argument today about just what is going on with our 
climate.  There can be no question that it is getting warmer (ever since the 
Industrial Age) and that CO2 and other "greenhouse" gases have increased in the 
atmosphere.  Whether this increase is a recurring phenomenon and has little 
to do with the burning of fossil fuels is still being debated.  For example, 
during the Carboniferous Era, CO2 was probably in greater abundance in the 
atmosphere than it is today.  But, then, the composition of gases in the atmosphere 
was considerably different that it is today.  I don't think there is any 
disagreement that the Earth's ice fields and glaciers are melting.  Whether enough 
has done so to affect the North Atlantic conveyor, for example, remains to be 
seen and whether that will cause the sudden onset of another ice age is yet 
to be seen.  Perhaps, if another volcano explodes and sends hundreds of 
thousands of tons of gas and ash into the stratosphere to cut the amount of sunlight 
reaching the Earth's surface (the explosion of Mt. St. Helens pumped only 1% 
of the materials that the explosion of Pinatubo blew into the stratosphere!) 
and that in conjunction with the NA conveyor is speculation, of course, but 
there should be no doubt about the outcome should both occur . . .

Dave Karnstedt
Silverton, Oregon

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