THE ENGINE OF THE AIR 171 



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hence stabilized and extended climatic influence through the 

 ages makes an interesting basis for an interpretation of the 

 conditions now existing in and around the North Atlantic 

 Ocean and the possible effects it may have on the future of 

 our present Atlantic civilization. It is known that changes 

 in the volume and warmth of the Florida Stream as it leaves 

 the Caribbean are reflected in slight but nevertheless effective 

 differences in temperature of the Irminger Current that runs 

 from the north of Iceland down the east coast of Greenland 

 under the colder and lighter waters of the Arctic Sea. Recent 

 studies of this and other sources of information about the 

 north all point to our entrance — during the past fifty years 

 or so — into a warm trend along the polar front. A Russian 

 scientist named Scholkosky says that the surface layer of cold 

 waters in the Arctic is now only about 100 meters deep, or 

 less by half than it used to be. The mean annual surface tem- 

 perature of the sea has also risen since 1926 at Jacobshavn, 

 Greenland, by more than two degrees This, accompanied by 

 a retreat of the glaciers and the icecap throughout the north 

 for the past several decades, is probably due as much to a 

 a greater volume of the currents from the tropics reaching 

 Arctic waters as it is to their slight rise in temperature. In the 

 two years between 1927 and 1929 it was calculated that twenty 

 percent more Atlantic water than normal reached the Nor- 

 wegian Sea. This influx naturally influenced the climate on 

 shore and the fishing conditions beneath the sea. Except for 

 a brief relapse in 1934-35 and 1937-38, the persistence of this 

 warmer period in the north due to the activity of the Ocean 

 River has been reflected in the whole economy of the north- 

 ern fisheries. 



A. S. Jensen of Copenhagen has made a study of the recent 

 change in the Arctic climate. Since 1919, he says, the cod 

 have returned to the West Greenland coast and moved north 

 to 70° of latitude; previous appearances of cod were noted 

 in 1820 and 1840, but not since 1850. Together with the cod 



