Appendix D 



Very Large Tabular Icebergs: Ice Season 2002 and the Past 



LT Scott A. Stoermer, U.S. Coast Guard 

 Mr. Pip Rudkin, Provincial Airlines Limited 



Introduction 



Exceptionally large icebergs, commonly referred to as ice islands, came again into the public eye recently 

 with the breaking loose of a portion the Antarctic ice sheet roughly ten times the size of the island of 

 Manhattan (Dykstra, 2002). The glaciers of the North Atlantic, specifically along the western coast of 

 Greenland, are not as conducive to very large iceberg generation as southern hemisphere ice fields, but 

 do occasionally produce "Antarctic" size icebergs. Ice Season 2002 (February 17, 2002 through July 15, 

 2002) saw some of the largest North Atlantic icebergs on recent record. These icebergs were actively 

 tracked for a period of approximately two months during the summer, were photographed, and were even 

 examined with side-scan sonar instruments. This brief report documents this season's sightings and 

 provides some historical data and context for these phenomena. 



Background 



The International Ice Patrol has monitored icebergs that drift south along the coast of Labrador and onto 

 the Grand Banks of Newfoundland region since the sinking of the Titanic in April of 1912. The Labrador 

 Current carries the icebergs that calve, or break away, from glaciers in Greenland and northern Canada 

 southward from Baffin Bay and Davis Strait. Several glaciers are capable of producing icebergs that end 

 their journey on the Grand Banks. Specifically, the Ward Hunt ice shelf, the Humboldt Glacier, and the 

 Petermann Glacier are likely sources of ice islands as the basin conditions seem to favor the production of 

 large tabular icebergs (Robe, 1977). As defined by Bowditch, an ice island is a piece of glacial ice that 

 rises roughly 10 meters above the ocean's surface and has an overall thickness of about 50 meters. 

 Often, ice islands will have a wave-like surface, appearing ribbed from the air. The surface area of an ice 

 island can range from a few thousand square meters to hundreds of square nautical miles. Thusly, ice 

 islands are not necessarily huge, in terms of surface area, but are unusually thin and flat-topped. 



No matter the source, tracking and monitoring the danger posed by icebergs to transatlantic shipping 

 interests is the responsibility of the International Ice Patrol. The offshore oil and gas industry has a keen 

 interest in typical iceberg drift tracks as well as average iceberg mass and size distribution as more 

 facilities, both fixed and mobile, are being moved onto the Grand Banks. Ice islands, due to their limited 

 draft, pose a unique threat for the oil and gas industry as they can drift into much shallower water than 

 other icebergs. This possibility increases the risk to current facilities as well as for the placement of new 

 facilities, even as many move to locations on the Grand Banks. The sheer mass of an ice island makes its 

 threat to a facility very great and limits many currently employed iceberg management techniques (i.e. 

 towing). The needs and concerns of the oil industry and the responsibilities of the International Ice Patrol 

 make the study of ice islands, similar to that tracked during the 2002 season very interesting. 



One of the agencies that is highly involved in iceberg tracking for a number of different organizations is the 

 Environmental Services division of Provincial Airlines Limited (PAL). PAL is a privately owned Canadian 

 company that performs contract sea ice and iceberg reconnaissance for the Canadian Ice Service, 

 Department of Fisheries and Oceans Canada (DFO) as well as private industry clientele. PAL, during the 

 height of the ice season, engages in iceberg reconnaissance and management for the Grand Banks 

 offshore oil and gas industry. Specifically, PAL tracks icebergs in the vicinity of oil and gas facilities and 

 moves (tows) icebergs if necessary to eliminate the threat to platforms and rigs. 



51 



