This report summarizes the current scientific knowledge on projected sea level changes as it applies to B.C. during the 21st century to inform decision-making and planning by coastal communities and other authorities.
The 21st century is expected to witness a continued rise in global average sea level as a result of the melting of continental glaciers and ice caps, and warming (expansion) of the upper ocean. At the regional scale, sea level will change in response to these global effects, as well as local effects, including ocean and weather conditions and vertical movements of the land due to geological processes. Consequently, the expected changes in sea level for the British Columbia coast will differ from the global projections; they will not be uniform. For instance, estimates of most probable sea level rise range from 11 cm at Nanaimo to more than 50 cm in parts of the Fraser River delta. Because of the many uncertainties in measuring past sea level changes and predicting future sea levels, the possible range could be much greater. Applying a possible, but extreme, global rise rate, sea level could rise 80 cm for Nanaimo and 120 cm for the Fraser River delta by 2100. The anticipated changes in sea level could have significant consequences for areas currently protected by dikes (such as the Fraser and Squamish deltas), where coastal erosion is already an issue (eastern Graham Island, Haida Gwaii), or where development and harbour infrastructure is close to present high tide limits. Of particular concern will be extreme weather events, such as storm surges, occurring at the same time as these high sea levels. These extreme events can add as much as one metre to sea levels, regardless of local shoreline features and waves.
Bornhold, Brian. 2008. Projected Sea Level Changes for British Columbia in the 21st Century. Ministry of Environment