342 annual report smithsonian institution, 1908. 

 Exaggerated Estimates of Climatic Changes. 



The range of climatic variations in the past has been often greatly 

 exaggerated, thereby leading to the apparent necessity for revolution- 

 ary changes in former meteorological conditions. But the climatic 

 changes we have to explain appear to have been either local in area or 

 moderate in degree. 



The opinion that there have been fundamental changes in climate 

 is based mainly upon the evidence of former glaciations and on the 

 supposed existence of tropical climates in the arctic regions. That 

 tropical or subtropical conditions once prevailed in the Arctic Circle 

 is affirmed on the reported occurrence there of fossil coral reefs and 

 tropical vegetation. I have previously quoted evidence to show that 

 this view is greatly exaggerated." One notice of that paper described 

 its views as " tres bardie," but I am not aware of any refutation of its 

 conclusions. The idea of the former tropical condition of Greenland 

 is still confidently asserted. Thus Doctor Ekholm ^ refers to the 

 nearly tropical climate that prevailed in the arctic regions during the 

 Cretaceous age, when he estimates that the mean temperature was 

 36° F. higher than during the Pleistocene. But so far as I know the 

 evidence there is no proof that the arctic regions ever had a sub- 

 tropical or even a w^arm, temperate climate. 



the evidence or fossil corals. 



The Arctic Ocean has been described as having been a coral sea in 

 Silurian and Carboniferous times. This view led to Blandet's sugges- 

 tion — well known by its advocacy by Sir John Murray — that iii 

 Paleozoic times light and heat were equally distributed throughout 

 the world; and also to the theories that the heat from the sun is 

 diminishing owing to the smaller size of the sun, as suggested by 

 Helmholtz, or to its lower intensity, as advocated by Dubois. But 

 the fossil faunas of the arctic seas all show the dwarfing eifect of 

 unfavorable conditions when compared to the contemporary faunas 

 in the seas to the south. 



Corals of reef-building genera have lived in the arctic regions; but 

 I have seen no arctic specimens larger than nodules which could have 

 grown in a cool sea. The asserted existence of arctic coral reefs in 

 Silurian times was based on a collection made in Grinnell Land, 

 which is now in the British Museum. But the specimens show noth- 

 ing more than the growth of small nodular corals, such as may have 

 grown in a temperate sea. Paleozoic corals have also been found in 

 the Timan-Urals and in the Silurian rocks of the New Siberian 



o " Some problems of Arctic Geology. II. Former arctic climates." 

 6 Ekholm ; op. cit., pp. 25, 26. 



