148 DISCUSSIONS IN CLIMATOLOGY. 



on former occasions, which would greatly increase the 

 volume and temperature of the stream and deflect 

 more of its waters into the Arctic Ocean would, 

 there is little doubt, confer on the polar regions a 

 climate suitable for plant and animal life. At present 

 the Gulf Stream bifurcates in mid- Atlantic, one branch 

 passing north-eastwards into the Arctic regions, whilst 

 the larger branch turns south-eastwards by the Azores, 

 and after passing the Canaries re-enters the equatorial 

 current. As the Gulf Stream, like other great currents 

 of the ocean, follows almost exactly the path of the 

 prevailing winds * it bifurcates in mid- Atlantic simply 

 because the winds blowing over it bifurcate also. Any 

 physical change which would prevent this bifurcation 

 of the winds and cause them to blow north-eastwards 

 would probably impel the whole of the Gulf Stream 

 waters into the Arctic seas. All this doubtless might 

 quite well be effected without any geographical changes, 

 although changes in the physical geography of the 

 North Atlantic might be helpful. 



These considerations regarding the influence of the 

 Gulf Stream point to another result of an opposite 

 character. It is this: if a large increase in the volume 

 and temperature of the stream would confer on Green- 

 land and the Arctic regions a condition of climate 

 somewhat like that of North-western Europe, it is 

 obvious, as has been shown at length on former 

 occasions, that a large decrease in its temperature and 

 volume would, on the other hand, lead to a state of 

 things in North-western Europe approaching to that 

 which now prevails in Greenland. A decrease leads to 

 a glacial, an increase to an interglacial condition of 

 things. 



Sir William Thomson on Mild Arctic Climates. — 



* See ' Climate and Time ' p. 213. 



