the actual weather pattern of the last 

 warm time, 35 million years ago (see 

 Chart 2) and the successive patterns as 

 cooling progressed. If we know these, 

 we can presume that the warming trend 

 will again bring each stage to us succes- 

 sively in reverse. 



The results of our studies are fascinat- 

 ing, but not yet conclusive. We can ex- 

 pect the present warming to continue 

 for a minimum of 200 years, and prob- 

 ably much more. This should cause — 

 but we are not yet sure — a change in the 

 basic wind circulation of the northern 

 hemisphere. If it does, Chicago may be- 

 come as dry as west-central Texas — but 

 of this we are even less sure. Certainly 

 the present Illinois drought is a local, 

 temporary misfortune unrelated to any 

 long-term trend. 



However, the long-term trend is caus- 

 ing our generally warmer, drier winters, 

 and is thereby seriously altering our 

 ground-water supply. Farther west, sev- 

 eral dams and irrigation projects, built 

 on the assumption that past conditions 

 would continue, are already suffering 

 perennial water shortages which can be 

 expected to increase. There is no need 

 for panic or for crash programs, but defi- 

 nite, practical reasons for pursuing these 

 studies of long-range climatic trends are 

 already with us. 



One other important result of the 

 present warming trend will affect the 

 life of everyone on earth. As the polar 

 ice melts, sea level will rise, slowly at 

 first but with increasing speed. This 

 has already started. Sea level is now 

 rising two feet per century; in 1920 the 

 rise was one inch in two centuries. The 

 most conservative estimates anticipate a 

 total rise of over one hundred feet. This 

 would drown out Boston, New York, 

 Philadelphia, Baltimore, and other 

 crowded areas the world over. Alto- 

 gether, about five hundred million peo- 

 ple would be forced to move; where on 

 this crowded earth they would go will be 

 a major problem. How soon will this 

 happen? Certainly not during our gen- 

 eration or our children's, but beyond 

 that we cannot be sure. Probably it will 

 not happen during the next century. 



Climate, like everything else in our 

 environment, is dynamic and changing. 

 Our Museum is taking part, along with 



*"""" ICE AGES OF THE GEOLOGIC PAST CHART 



Of J«ar. 



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"Mom THE LAST HUNDRED MILLION YEARS 



of ,««n 



«90 100 90 80 70 60 80 40 30 20 10 pr»»tnt 



other research institutions, in studies mates of the future, and to prepare for 

 that may enable us to predict the cli- them, (end) 



MARCH Page 7 



