Canada’s Marine Coasts in a Changing Climate
Canada is a coastal nation. All provinces and territories, with the exception of Alberta and Saskatchewan, share in the approximately 243 000 km of coastline. Indigenous peoples have lived along Canada’s coasts and utilized coastal resources for thousands of years, and many First Nation, Métis and Inuit communities retain very close ties to the coast. Today, about 6.5 million Canadians live near our marine coasts, and more than $400 billion in goods are shipped annually through Canadian ports (Association of Canadian Port Authorities, 2013).
Science assessments at global and national scales highlight the importance of understanding and addressing climate change impacts in coastal regions. Globally, coastal flooding could displace hundreds of millions of people in the current century, with the annual costs for adaptation measures such as new dike construction, dike maintenance and beach nourishment estimated to be US$25-270 billion per year by 2100. Within Canada, climate change presents a range of risks, with higher temperatures, changing precipitation patterns and storminess, rising sea level and diminishing sea ice being the key climate changes discussed throughout this report. The magnitude, importance and sometimes direction of these changes vary between coastlines. How Canada adapts to the coming changes will be critical to the sustainability and continued prosperity of the country and its coastal regions.
This publication* includes an overview of the geological and physical aspects of the Canadian coast (Chapter 2); the environmental and societal sustainability of Canada’s marine coasts (Chapter 3); three regional chapters that examine issues in Canada’s East, North and West Coast regions (Chapters 4, 5 and 6, respectively); and a concluding chapter that addresses frequently asked questions (Chapter 7).
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All of Canada’s coastal regions are being impacted by changing climate, and these impacts will continue to increase in the future. The resulting risks and opportunities vary within and between regions, reflecting differences in both human and natural systems and in climate sensitivity. Key climate-related impacts emphasized in this report include changes in sea level, sea-ice extent, coastal flooding and ecosystem services.
As a highly developed nation, Canada possesses the capacity needed to adapt to these impacts, but adapting in an efficient and proactive manner requires planning that accounts for the changing nature of climate risks.
Limited site-specific knowledge and capacity to respond can be barriers to adaptation at the local scale, which may be best addressed through further collaboration between levels of government, as well as with academia and other nongovernment players. Collaboration and innovation are essential for achieving a vision of a sustainable and resilient coastal Canada.
The following points represent high-level conclusions from Canada’s Marine Coasts in a Changing Climate, and are discussed further in the synthesis by Donald S. Lemmen and Fiona J. Warren in Chapter 1:
- Changing climate is increasingly affecting the rate and nature of change along Canada’s highly dynamic coasts, with widespread impacts on natural and human systems.
- Recent extreme weather events demonstrate the vulnerability of coastal infrastructure.
- Changes in the extent, thickness and duration of sea ice, both in the North and in some areas of the East Coast region, are already impacting coasts, ecosystems, coastal communities and transportation.
- Sea-level changes will vary significantly across Canada during this century and beyond. Where relative sea level is rising, the frequency and magnitude of storm-surge flooding will increase in the future.
- Knowledge of climate risks and the need for adaptation in coastal areas is increasing, with many examples of local and regional governments in Canada taking action on adaptation.
- A range of adaptation measures will be needed in most settings to address the complex array of changes. Alternatives to hard coastal-protection structures can be effective in addressing coastal erosion and flooding in many areas. Soft-armouring measures include maintaining and/or restoring beaches, marshes and coastal vegetation, all of which can lessen the damaging effects of tides, currents, waves and storms.
- It is imperative that future development be undertaken with an understanding of the dynamic nature of the coast and changing coastal risks. Monitoring and assessment of the effectiveness of actions taken to date, as well as research to fill data and knowledge gaps, would help inform sustainable planning and development.
Summary of regional chapter key findings
CHAPTER 4: PERSPECTIVES ON CANADA’S EAST COAST REGION
- Air temperatures, sea-surface temperatures and ocean acidity have all increased in the region during the past century, while sea-ice cover has decreased. Projected climate changes through the 21st century include continued warming of air and water temperatures, and increased precipitation, acidification and water stratification. Sea level will rise, with significant regional variability. Sea ice will decrease in area, thickness, concentration and duration, with volume likely to be reduced by more than 95% by the end of the 21st century.
- Sea-ice cover and sea-level rise are key determinants of coastal erosion rates. Increases in coastal erosion have been documented along many coasts in the region during years characterized by mild winters and low ice cover- age. Future coastal-erosion rates will likely increase in most areas.
- There are many adaptation measures that promote the resilience of coastal areas. These include protection, revegetation and stabilization of dunes; maintenance of sediment supply; and provision of buffer zones, rolling easements or setbacks that allow the landward migration of the coastline.
- Although hard coastal defence structures may be necessary to address sea-level rise and coastal flooding in some situations, particularly in urban areas, such structures disrupt coastal processes and can exacerbate erosion, sedimentation and coastal squeeze, leading to degradation and loss of coastal habitats and ecosystem services. Retreat, sand nourishment and managed realignment represent alternatives to hard coastal defence structures.
- Experience in the East Coast region has shown that mechanisms such as setbacks, which control or prohibit coastal development, can be challenging to implement. However, it is often even more difficult to remove and relocate buildings from an eroding coastline or flood-susceptible area. Selection of appropriate adaptation options may be particularly challenging in unincorporated areas where summer cottages, secondary homes or principal dwellings are established parallel to the shore in a ribbon fashion.
- Provinces and communities across the region have made advances in identifying vulnerabilities to climate change impacts through collaboration with academia, the private sector and nongovernmental organizations. Many have begun planning for adaptation, while others have moved from planning to implementation of adaptation strategies, although this remains a challenge for many. Few are engaged in ongoing monitoring of the effective- ness of implemented adaptation strategies.
CHAPTER 5: PERSPECTIVES ON CANADA’S NORTH COAST REGION
- The environment and socio-economic characteristics of the northern coast are unique. Inhabited primarily by Indigenous populations living in small remote communities, Canada’s northern coastline is vast, representing more than 70% of all Canadian coasts. The presence of sea ice is a defining feature of this coast, affecting transportation access, shaping geomorphological processes and providing a platform for culturally valued and economically important harvesting activities. Social, economic and demographic characteristics of northern coastal communities differ considerably from the Canadian average, with resource development and public administration being mainstays of northern economies.
- The northern coast is a hotspot for global climate change. The region has experienced some of the most rapid climate change anywhere on the globe, and projected future climate changes for the northern coastline will continue to be significant. Impacts on the physical environment include declining sea-ice concentration, earlier ice break-up and later freeze-up, a lengthening of the ice-free open-water season, permafrost warming and thaw, coastal erosion, sea-level rise and changing weather patterns, including wind and waves.
- Northern coastal communities, ecosystems and economic activities are being affected by climate change impacts. Many communities have a high sensitivity to climate change impacts, as they are situated on low-lying coasts and have infrastructure built on permafrost, economies strongly linked to natural resources and dependence on land-based harvesting activities. Negative impacts of climate change on a variety of sectors have been widely documented across the northern coast. New opportunities associated with a longer ice-free shipping season are also recognized, but increased marine traffic also brings risks.
- Climate change will exacerbate existing vulnerabilities. Vulnerability differs significantly by region and community and, within communities, as a function of geographic location, nature of climate change impacts and human factors. Capacity to manage climate change is high in some sectors, such as subsistence harvesting and health, but is being undermined by long-term societal changes. In other sectors, such as infrastructure, limitations in climate risk-management capacity (e.g., institutional, financial, regulatory) result in continuing high vulnerabilities.
- Northern coastal communities and industries are adapting. Adaptation actions are already taking place in the North, with examples of adaptation planning documented across all levels of government. The effectiveness and sufficiency of the existing responses have not been evaluated, although barriers to adaptation, including limited resources, institutional capacity and a lack of ‘usable’ research, have been identified. Publicly available information on how the private sector is approaching adaptation is limited.
- Opportunities for additional adaptation are diverse. Mainstreaming adaptation into ongoing policy initiatives and priorities to address underlying socio-cultural determinants of vulnerability can help address the risks posed by climate change to harvesting activities, culture and health. Adaptation actions targeted at specific climatic risks are also required, particularly to manage the impacts of climate change on community and industrial infrastructure.
CHAPTER 6: PERSPECTIVES ON CANADA’S WEST COAST REGION
- Sea-level rise will not affect all areas of the British Columbia coast equally, largely due to differences in vertical land movement. The largest amounts of relative sea-level rise are projected to occur on the Fraser Lowland, southern Vancouver Island and the north coast. Planning guidance for sea-level rise developed by the British Columbia government provides planning levels that slightly exceed the peak values (95th percentile) of the sea-level projections at 2050. This could be considered a margin of safety that allows for possible additional sea-level rise arising from factors with significant uncertainty, such as contributions from the Antarctic Ice Sheet.
- Storm-surge flooding presents a greater threat to coastal communities than sea-level rise alone. Coastal communities are already coping with extreme water levels associated with climate variability (e.g., El Niño/La Niña Southern Oscillation) and storm-surge flooding. The risks associated with these events are expected to increase as sea level rises. Residential, commercial, institutional and municipal property and infrastructure in the region are vulnerable, and communities have begun to take action to reduce the risk through adaptation measures such as shoreline protection.
- Marine ecosystems will be affected as species move northward in response to warmer water. Southern species will expand their range northward into British Columbia as the ocean warms, while species that today inhabit the south coast region, including salmon, will also migrate north. In the southern part of the province, warmer ocean-surface temperatures will decrease the habitable range of shellfish and changing ocean acidity will affect their reproductive success. Adaptation in the commercial-fisheries sector will involve shifting the types of species being fished and relocating operations. First Nations, who rely strongly on salmon for cultural uses, often have fewer options for adaptation to changes in distribution and abundance of fish species.
- Changing precipitation patterns will affect summer water availability and the timing of salmon runs in some watersheds. Winter precipitation is expected to increase overall, with more falling as rain and less as snow. Less precipitation is expected during the summer and this, combined with reduced snowpack, will decrease the amount of water available for some regions in late summer and autumn. River levels will decrease during this period and water temperature is likely to increase as a result. Increased river temperature would affect the timing of salmon runs because these fish do not enter rivers until water temperatures cool to approximately 15°C.
- Climate change adaptation is gaining momentum in British Columbia. Governments have been moving forward on climate change adaptation, particularly regarding sea-level rise and coastal-flooding issues. Notable projects include a cost assessment of upgrading Metro Vancouver’s dike system; a risk study for sea-level rise in the Capital Regional District; the City of Vancouver’s new Flood Construction Level that considers sea-level rise; the placement of boulders below the low-tide level off the West Vancouver shore to mitigate storm-surge impacts; and the development of a Sea-Level Rise Primer for local governments.
This assessment is a product of Canada’s Adaptation Platform, which brings together representatives from government, industry and professional organizations, to collaborate on adaptation priorities. For more information on the Adaptation Platform, and to download new products, including case studies, adaptation tools, guidance documents and reports, please visit: adaptation.nrcan.gc.ca
- Donald S. Lemmen – Climate Change Impacts and Adaptation Division Natural Resources Canada
- Fiona J. Warren – Climate Change Impacts and Adaptation Division Natural Resources Canada
- Thomas S. James – Geological Survey of Canada Natural Resources Canada
- Colleen S.L. Mercer Clarke – Telfer School of Management University of Ottawa
Lemmen, D.S., Warren, F.J., James, T.S. and Mercer Clarke, C.S.L. editors (2016): Canada’s Marine Coasts in a Changing Climate; Government of Canada, Ottawa, ON, 274p.