268 Prof. S. Arrhenius on the Influence of Carbonic Acid 



Orel, and Nijni Novgorod), Germany and Austria (to the 

 Harz, Erz-Gebirge, Dresden, and Cracow). At the same 

 time an ice- cap from the Alps covered Switzerland, parts of 

 France, Bavaria south of the Danube, the Tyrol, Styria, and 

 other Austrian countries, and descended into the northern part 

 of Italy. Simultaneously, too, North America was covered with 

 ice on the west coast to the 47th parallel, on the east coast to 

 the 40tb, and in the central part to the 37th (confluence of 

 the Mississippi and Ohio rivers). In the most different parts 

 of the world, too, we have found traces of a great ice age, as 

 in the Caucasus, Asia Minor, Syria, the Himalayas, India, 

 Thian Shan, Altai, Atlas, on Mount Kenia and Kilimandjaro 

 (both very near to the equator), in South Africa, Australia, 

 New Zealand, Kerguelen, Falkland Islands, Patagonia and 

 other parts of South America. The geologists in general 

 are inclined to think that these glaciations were simultaneous 

 on the whole earth *; and this most natural view would 

 probably have been generally accepted, if the theory of Croll, 

 which demands a genial age on the Southern hemisphere at the 

 same time as an ice age on the Northern and vice versa, had 

 not influenced opinion. By measurements of the displacement 

 of the snow-line we arrive at the result, — and this is very 

 concordant for different places — that the temperature at that 

 time must have been 4°-5° C. lower than at present. The last 

 glaciation must have taken place in rather recent times, 

 geologically speaking, so that the human race certainly had 

 appeared at that period. Certain American geologists hold 

 the opinion that since the close of the ice age only some 7000 

 to 10,000 years have elapsed, but this most probably is greatly 

 underestimated. 



One may now ask, How much must the carbonic acid vary 

 according to our figures, in order that the temperature should 

 attain the same values as in the Tertiary and Ice ages respect- 

 ively ? A simple calculation shows that the temperature in 

 the arctic regions would rise about 8° to 9° C, if the 

 carbonic acid increased to 2*5 or 3 times its present value. 

 In order to get the temperature of the ice age between the 

 40th and 50th parallels, the carbonic acid in the air should 

 sink to 0*62 — 0*55 of its present value (lowering of temperature 

 4°-5° C). The demands of the geologists, that at the genial 

 epochs the climate should be more uniform than now, accords 

 very well with our theory. The geographical annual and 

 diurnal ranges of temperature would be partly smoothed 

 away, if the quantity of carbonic acid was augmented. The 



* Neumayr, Erdgeschichte, p. 648 ; Nathorst, I. c. p. 992. 



