Global Warming was Rain Fall
DaveKarn@aol.com (Mon, 09 Jan 2006 06:18:32 PST)

In a message dated 1/7/2006 8:09:51 PM Pacific Standard Time,
plantlady@beautifulblooms.ab.ca 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