Hi Brian,
To my knowledge, the ozone depletion cause is nowhere near as clear-cut as
you ake it sound.
But back to 'global warming potential-GWP.'
Earth has gone through quite a number of climatic cycles, alternating between
cool periods and warmer [Climatic Optima] periods. Since the end of the last
glacial period, the Wisconsin or Würm Stage, about 6 to 7,000 years ago,
there have been a number of warm and even hot periods. The hot Holocene
Optimum occurred between 6 to 5,000 and 3,000 B.C., and the Little Climatiic
Optimum (LCO) or Medieval Warming Period from 750 to 1215; cold periods
occurred from 900 to 300 B.C., moderating to cool from 300 B.C. to 750 A.D.
During the LCO, ice and severe weather vanished from the Northern seas,
allowing the Vikings to expand to Iceland, Greenland [it was green, fertile,
and supported a population of 3,000 with nearly 400 farms at its height], and
Markland ["Wooded Land"--today's Labrador], and Vinland [today's
Newfoundland--where then grapes, currents, and gooseberries grew]. The LCO
also brought about the European Agricultural Revolution, with vineyards 300
miles farther north than today, and England producing high-quality wines.
The end of the LCO spelled doom to the Viking settlements, other than
Iceland, and crop yields fell by a third throughout Europe, leading to some
of the worst famines in 1315 to 1317 and 1347, driggering the medieval
depression which lasted a century and a half and bringing the return of the
plague.
So, in history, it was the cooling, not the warming, that brought about human
disasters on a wide scale.
Those interested, may consult: Crowley, J. J., and G.R. North,
"Paleoclimatology," (Oxford, 1991), or Gimpel, J., "The Medieval Machine. The
Industrial Revolution of the Middle Ages," (N.Y., 1976), or Jones, G., "A
History of the Vikings,"(Oxford, 1984).
Werner Engelmaier
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