 merrie says: Reid Bryson of the University of Wisconsin points out that the Earth’s average temperature during the great Ice Ages was only about seven degrees lower than during its warmest eras — and that the present decline has taken the planet about a sixth of the way toward the Ice Age average. Others regard the cooling as a reversion to the “little ice age” conditions that brought bitter winters to much of Europe and northern America between 1600 and 1900 — years when the Thames used to freeze so solidly that Londoners roasted oxen on the ice and when iceboats sailed the Hudson River almost as far south as New York City. Just what causes the onset of major and minor ice ages remains a mystery. “Our knowledge of the mechanisms of climatic change is at least as fragmentary as our data,” concedes the National Academy of Sciences report. Meteorologists think that they can forecast the short-term results of the return to the norm of the last century. They begin by noting the slight drop in overall temperature that produces large numbers of pressure centers in the upper atmosphere. These break up the smooth flow of westerly winds over temperate areas. The stagnant air produced in this way causes an increase in extremes of local weather such as droughts, floods, extended dry spells, long freezes, delayed monsoons and even local temperature increases — all of which have a direct impact on food supplies. “The world’s food-producing system,” warns Dr. James D. McQuigg of NOAA’s Center for Climatic and Environmental Assessment, “is much more sensitive to the weather variable than it was even five years ago.” Climatologists are pessimist... |
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