| Résumé | Sea ice extent can serve as proxy environmental data for long-term variability of the climate system, as input to test climate change models or to compare to historical fish landing data. The Newfoundland-Grand Banks sea ice record has been previously assembled over a two-hundred-year period by the second author. We have now compiled an historical record of the sea ice in the Gulf of St. Lawrence on the Scotian Shelf of Atlantic Canada. Data have been compiled on an annual basis from the early 1800s to 1962; ice data for these areas from 1963 to the present are available and archived by the Canadian Ice Service. The current study was undertaken to extend the sea ice database back in time as far as possible, and to provide a means of testing statistical relationships being identified from analysis of the more recent forty-year data set. A variety of data sources were used in the compilation of ice records including ice patrol and shipping reports, local newspapers, lighthouse records and other holdings in the U.S. and Canadian National Archives. In the order of 20,000 ice records, amounting to over 500 pages of re-typed print, were found spanning the years 1752 to 1962; even Canada's first newspaper has an ice report on Monday, March 23, 1752 in The Halifax Gazette! Information for early years is sporadic, but is continuous from about 1820. In addition, annual Canadian government Gulf of St. Lawrence ice survey reports were identified covering the period from the mid-1950s so the emphasis in the search was for ice records prior to that time. All the available resources are described, as is the method that was used in condensing the large number of reports into meaningful monthly ice charts for a season which could extend from December until June. For these, the areal coverage of sea ice was calculated and the ice boundary lines digitized. The resultant time series of ice extent can be used to identify trends and anomalies, and to compare to other time series of North Atlantic ice extent such as the Grand Banks and Baltic ice extents, the Iceland sea ice record, and to climatic factors such as the North Atlantic Oscillation. Natural gas development is well underway on Sable Island Bank of the Scotian Shelf, and while no ice has visited Sable Island or the gas development areas in recent memory, it is clear from the Scotian Shelf ice record that intrusions into the current ice production areas are not unusual historically. In 1882 a major sea ice incursion southward from Grand Banks allowed sea ice, icebergs, and apparently much colder bottom sea water to intrude much further south than usual. Sea ice was seen off New England, and a massive fish kill of benthie dwelling tile fish and robin fish that suffered sub-lethal temperatures was the result. Estimates at the time, by ships passing in and out of the Boston-Gloucester area of Massachusetts, placed 60,000,000 dead and dying fish on the sea surface. |
|---|
