The trend of the 19 year running average Belle Isle/Ivigtut pressure 

 difference is in general agreement with the trend of average iceberg 

 counts, thus indicating that the iceberg record is valid. There is an 

 initial period of moderate pressure differences followed by a rise in 

 the 1920's which reached a peak of 9 millibars in the late 1920's, about 

 6 or 7 years before the iceberg intensity peak. The decline in the 

 average pressure difference since 1929 has been almost uninterrupted. 



The 19 year running average air temperature at Torbay has, as 

 expected, varied more or less inversely with the iceberg count. After 

 a low of about -5°C in the early 1920's, about 18 years before the 

 iceberg maximum, the average has climbed steadily, reaching about -2.7°C 

 by the late 1950' s. The air temperatures at Torbay also correlate 

 inversely with the Belle Isle/Ivigtut pressure difference, as expected. 



Conclusions 



The evidence indicates that there has been a significant decrease 

 in the severity of the iceberg threat to the northwest Atlantic since 

 the 1880' s. This decrease is apparently substantiated by a trend 

 toward winds less favorable for the drift of icebergs along the 

 Labrador and Newfoundland coasts, and by an increase in air temper- 

 ature along the Newfoundland coast. 



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