"Leaders in climatology and economics are in agreement that a climatic change is taking place and that it has already caused major economic problems throughout the world."

Scientists are confident that unless man is able to effectively modify the climate, northern regions, such as Canada, the European part of the Soviet union, and major areas in North China, will again be covered with 100 to 200 feet of ice and snow. That this will occur within the next 2500 years they are quite positive; that it may occur sooner is open to speculation..
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.Clouds serve to moderate whatever climate trend is under way; if the earth's surface temperature climbs for whatever reason, more water evaporates and rises to form more cloud cover. This increases the albedo and lowers the rate of heating. Ice and snow, on the other hand, provide positive feedback; if the average year round temperature decreases, the extent of ice and snow coverage increases and reflects more of the incoming sunlight back to space. The result is to lower the rate of heating still more, particularly in the regions closest to the poles..
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.Climate change at the end of interglacial periods is rather sharp and dramatic. Excellent historical evidence exists from areas on the European planes which once were Oak Forest and were later transformed into Poplar, then into Burch, and finally into tundra within a 100 year span. Thus the researchers of the CLIMAP group (CLImatic MAPing) hypothesize that the change from interglacial to glacial time could take place in less than 200 years. An example of rapid climate changes are the remains of frozen mastodons completely preserved in Siberian and North American ice packs.