45§ POPULAR SCIENCE MONTHLY 



CHANGES OF CLIMATE 



BY ROBERT DEC. WARD 

 HAEVABD UNIVEESITY 



Popular Belief in Climatic Change. — Belief in a change in the 

 climate of one's place of residence, within a few generations, and even 

 within the memory of living men, is widespread. It is confined to 

 no special region or people. It finds support among the most intelli- 

 gent as well as among the uneducated. Here it may be the view that 

 the climate is growing milder; there, that the winters are becoming 

 more severe ; here, that there is increasing aridity ; there, that the rain- 

 fall is greater. Whenever a season attracts attention because of weather 

 conditions which seem in any way unusual, this belief is strengthened. 

 This popular impression has often found support in the facts of dis- 

 tribution, or the dates of flowering or ripening of certain cereals or 

 fruits. It is asserted that because grapes, or corn, or olives, for ex- 

 ample, are now no longer grown in parts of Europe where their culti- 

 vation was once an important occupation, we must conclude that the 

 climate has changed from a favorable to an unfavorable one. 



Evidences of Climatic Changes within Historical Times. — Evidence 

 is constantly being brought forward of apparent climatic variations 

 of greater or less amount which are now going on. Such reports, 

 largely those of travelers or explorers in little-known regions, are 

 usually based on fluctuations in the extent of inland lakes; on the 

 discovery of abandoned dwelling sites, the ruins of aqueducts and irri- 

 gating canals, and the like. Thus we have accounts of a gradual 

 desiccation which seems to have been going on over a large region in 

 Central Asia, during historical times. In eastern Turkestan the lakes 

 have been reported as drying up, Lake Balkash falling one meter in 

 about fifteen years, and Lake Alakul gradually becoming a salt deposit. 

 In his work on Turkestan, Muschketoff gives numerous examples of 

 progressive desiccation, and Bossikoff speaks of the drying up of the 

 lakes on the northern side of the Caucasus. The same thing is reported 

 of lakes in the Pamir. Prince Kropotkin believes that the desiccation 

 of Central Asia in the past drove the inhabitants out on to the lowlands, 

 producing a migration of the lowland peoples and thus bringing on 

 the invasions of Europe during the first centuries of our era. In his 

 recent work on the basin of eastern Persia and Sistan, Huntington 

 believes that, so far as it can be made out, the history of Sistan also 



