-—-- Ktfchikon, Alasko 

 — •— SKogwoy, Aloaha 



Figure 25. Variation in annual MSL at Ketchikan and Skagway, Alaska. 



Figures 21 to 25 and some additional tide data are summarized in Table 5. Trends and 

 variability of the annual MSL are shown for 50 NOS tide stations for the period of record 

 through 1972 and for the common period 1940 to 1972. AH but two stations south of 

 Alaska show a rising trend when the full period of record is considered. The Alaska stations 

 in this table, other than Ketchikan, show a trend toward falling sea level over tlie same 

 period. 



Tide gage records from many other stations show much the same pattern of changes as 

 shown by the NOS records. Hicks (1978) summarizes data for the conterminous States for 

 an additional five generally homogenous regions. The overall national trend is 1.5 dynamic 

 millimeters per year with generally higher values along the mid-Atlantic coast and lower 

 values along the Pacific coast. 



During the past 6,000 years, worldwide sea level has changed much more slowly. There is 

 considerable controversy as to whether sea level peaked one or more times during this 

 interval, or whether it gradually approached its present high elevation. Resolution of this 

 highly contested question may be of Uttle practical concern to coastal engineers. It is more 

 important to note that proponents on both sides of the controversy would agree that sea 

 level has not been more than 3 or 4 meters above present elevations during the last 6,000 

 years. Higher stands, up to 100 meters above present sea level, occurred much earher in 

 geologic time. 



During the present period of a worldwide trend of rising sea level at midlatitudes, tide 

 gage records show that the coasts of Scandinavia, the British Isles, Canada, and Alaska have 

 experienced falling sea levels. 



57 



