| Abstract | The St. Lawrence River is an important trade corridor with significant vessel traffic and hundreds of infrastructure assets, such as ports, docks, dams, hydroelectric facilities and locks. The safe and effective operation of existing seaway assets, and the design of new infrastructure, depend on many environmental factors. The expected effects of climate change must be considered when planning future operations and construction. One concern for seaway operations is ice. An ice cover forms seasonally along most of the marine corridor from the Great Lakes to the Gulf of St. Lawrence. To evaluate the historical ice conditions along the upper St. Lawrence River, data are xamined for the section from the Iroquois Dam to Montreal, Quebec. Maximum annual shorefast ice thickness is determined from on-ice measurements, and compared to freezing degree day calculations based on air temperatures from weather stations and climate model hindcasts. Plausible future ice thicknesses are assessed from estimated freezing degree days using climate-modelled future air temperatures as input. Maximum annual ice thickness has declined over the past 70 years, and is expected to continue to decline in a warming climate. |
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