Coastal erosion and submergence
The effects of climate change are contributing to an increase in coastal erosion and submergence. However, there are still challenges in modelling these phenomena in a future climate.
Two of these challenges are:
The climate-related factors that contribute to erosion and submergence, such as ice, water level and waves, are complicated to project and involve significant uncertainties.
For example, the quality of winter storm surge and wave projections depends on the quality of atmospheric projections such as temperature, wind, and ice cover characteristics.
The ocean dynamics of the Estuary and Gulf of St. Lawrence are particularly complex to model. As a result, few modelling systems are currently capable of adequately and consistently projecting environmental conditions for the St. Lawrence Estuary and the Gulf of St. Lawrence regions.
Ocean dynamics
Ocean dynamics, also known as atmosphere-ice-ocean dynamics, involve various factors, such as thermal stratification, salinity, currents, tides, ice and the exchange of ocean heat and vapour with the atmosphere.
However, the degree of confidence with regard to the effects of climate change on ice cover and sea level is high. As a result, it is clear that the reduction or even the possible disappearance of ice cover, along with rising sea levels, will accentuate coastal erosion and submergence in many regions along the Estuary and Gulf of St. Lawrence.
On a global scale, projections estimate an average sea level rise of 0.77 m by 2100, according to the most pessimistic scenario (SSP5-8.5).
Quebec is no exception to this upward trend. In some regions, this trend is further accentuated by the glacial context. In the Magdalen Islands, for example, projections estimate a 0.87 m rise in relative sea level by 2100, according to the most pessimistic scenario (SSP5-8.5).
Despite the fact that ice cover projections for the Estuary and Gulf of St. Lawrence remain fragmentary, all point to a decrease in ice cover. By 2050, freeze-up (the formation of the ice cover) in the Estuary and Gulf of St. Lawrence will be about 30 days later.
