To scientists, these seemingly disparate incidents represent the advance signs of fundamental changes in the world's weather. Meteorologists disagree about the cause and extent of the trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic. “A major climatic change would force economic and social adjustments on a worldwide scale,” warns a recent report by the National Academy of Sciences, “because the global patterns of food production and population that have evolved are implicitly dependent on the climate of the present century.”
A survey completed last year by Dr. Murray Mitchell of the National Oceanic and Atmospheric Administration reveals a drop of half a degree in average ground temperatures in the Northern Hemisphere between 1945 and 1968. According to George Kukla of Columbia University, satellite photos indicated a sudden, large increase in Northern Hemisphere snow cover in the winter of 1971-72. And a study released last month by two NOAA scientists notes that the amount of sunshine reaching the ground in the continental U.S. diminished by 1.3% between 1964 and 1972.To the layman, the relatively small changes in temperature and sunshine can be highly misleading.
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. “Not only are the basic scientific questions largely unanswered, but in many cases we do not yet know enough to pose the key questions.”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.” Furthermore, the growth of world population and creation of new national boundaries make it impossible for starving peoples to migrate from their devastated fields, as they did during past famines.Climatologists are pessimistic that political leaders will take any positive action to compensate for the climatic change, or even to allay its effects.
They concede that some of the more spectacular solutions proposed, such as melting the Arctic ice cap by covering it with black soot or diverting arctic rivers, might create problems far greater than those they solve. But the scientists see few signs that government leaders anywhere are even prepared to take the simple measures of stockpiling food or of introducing the variables of climatic uncertainty into economic projections of future food supplies. The longer the planners delay, the more difficult will they find it to cope with climatic change once the results become grim reality.
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It is projected that man’s potential to pollute will increase six to eightfold in the next 50 years. If this increased rate of injection of particulate matter in the atmosphere should raise the present global background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5° K [3.5° C]. Such a large decrease in the average surface temperature of the Earth, sustained over a period of a few years, is believed to be sufficient to trigger an ice age.
— Science, “Atmospheric Carbon Dioxide and Aerosols,” July 9, 1971
Climatologists now blame those recurring droughts and floods on a global cooling trend. It could bring massive tragedies for mankind.
— Fortune, “Ominous Changes in the World’s Weather,” February 1974
Since the 1940s the mean global temperature has dropped about 2.7° F. Although that figure is at best an estimate, it is supported by other convincing data. When Climatologist George J. Kukla of Columbia University’s Lamont-Doherty Geological Observatory and his wife Helena analyzed satellite weather data for the Northern Hemisphere, they found that the area of the ice and snow cover had suddenly increased by 12% in 1971 and the increase has persisted ever since. Areas of Baffin Island in the Canadian Arctic, for example, were once totally free of any snow in summer; now they are covered year round.
— Time, “Another Ice Age?” June 24, 1974
Climatologists have advanced a number of theories to explain why the world’s climate is getting worse. The dominant school maintains that the world is becoming cooler, resulting in a loss of arable land at the higher latitudes and major shifts in rainfall patterns. A second school believes the world is warming, with equally serious consequences.
— Business Week, “The world’s climate is getting worse” August 2, 1976
Most scientists agree that today’s ice movement may reflect a worldwide cooling trend, but their explanations vary widely.
— National Geographic, “What’s Happening to Our Climate?” November 1976
Judging from the record of the past interglacial ages, the present time of high temperatures should be drawing to an end … leading into the next glacial age....
— National Science Board, 1972
What ever happened to global warming? Scientists have issued apocalyptic warnings for years, claiming that gases from cars, power plants and factories are creating a greenhouse effect that will boost the temperature dangerously.... But if last week is any indication of winters to come, it might be more to the point to start worrying about the next Ice Age instead. After all, human-induced warming is still largely theoretical, while ice ages are an established part of the planet’s history. — Time, “The Ice Age Cometh?” January 31, 1994