Sea level rise due to melting ice sheets and thermal expansion of the ocean poses serious risks for coastal communities. Elevated sea levels erode shorelines and inundate low-lying coasts; these changes, in turn, allow high tides and storm surges to reach unprotected areas further inland. The perturbed coastal environment will lead to severe impacts on health.

In British Columbia, 80% of the population lives within 5 km of the coast, with the majority concentrated in Metro Vancouver and southern Vancouver Island.[1] Along the north coast, many settlements in Haida Gwaii, as well as Kitimat and Prince Rupert, are near sea level.[1]

Displacement

Under current provincial estimations, sea levels around BC are projected to rise by 0.5 metre by 2050, and 1.0 metre by 2100, making many low-lying lands vulnerable to displacement from flooding tidal inflow and storm surge.[1]

Sea level rise will have both acute and long-term effects on those now living near to shore. Acutely, flooding can lead to residential water infiltration and consequent mold growth, cold water immersion, drowning, and other injuries.[2] Over the longer term, loss of coastal land will lead to population displacement. Given the growing population and limited land availability in BC, displaced residents may find themselves competing with others for valuable land on elevated ground.

Displacement also has long-term health impacts. A 2017 study from the United Kingdom found a significant increase in the rates of anxiety, depression, and posttraumatic stress disorder for individuals who were displaced as a consequence of flooding compared to those who experienced flooding but were not displaced.[3] Inability to return home after a flood acts as a stressor that induces or exacerbates malnutrition, hypertension, and cardiac events.[3,4]

In addition, much of the existing health infrastructure in BC will require relocation as a consequence of sea level rise, disrupting health services not only for people living near the ocean but those across the province who rely on these coastal facilities. Richmond and Delta hospitals in Metro Vancouver, which together serve a population of 300 000 people, are vulnerable to a 1-in-500-year storm surge even at today’s sea level.[5]

Food security

Sea levels are predicted to rise by up to 1.2 metres in the Fraser River Delta by 2100,[6] where BC’s most productive farmlands are situated. In all, over 4600 hectares of farmland lie within 1 metre of sea level.[1] Given that BC currently produces 48% of all foods consumed in the province,[7] flooding and saltwater intrusion pose serious food security risks. Adding to direct agricultural disturbances will be disruptions to ferry services and flooding of port terminals situated at sea level, which will affect food delivery to Vancouver Island and northern coastal communities that rely on maritime transport.

For fisheries-dependent communities, coastal erosion caused by sea level rise will lead to a loss of intertidal wetlands and upriver salmon breeding habitats, thereby reducing BC’s salmon and shellfish populations. Warming waters that lead to sea level rise also threaten BC’s wildlife salmon runs. This will particularly impact Indigenous communities and others who cultivate berries and harvest fish and shellfish.

Water security

Across BC, 28.5% of residents rely on groundwater for drinking, irrigation, or industrial needs.[8] As rises in sea level continue, the likelihood of saltwater infiltrating groundwater will increase and reduce the availability of freshwater for coastal communities. Along BC’s Gulf Islands, rising sea levels are already gradually causing saltwater intrusion of existing freshwater wells and aquifers.[9] Although the water supply for much of the Lower Mainland is located outside of coastal floodplains, sea water may damage wastewater treatment facilities, leading to spread of waterborne diseases such as E. coli or salmonella.

While its procession is gradual, sea level rise resulting from global climate change is occurring along the densely populated BC shoreline, posing both foreseeable and harder-to-foresee health risks for the province’s coastal residents. While sea level rise may look like an environmental issue, it has the potential to impact many of the determinants of health, affecting everything from access to health care services and safe and nutritious food to mental health.
—Kevin Liang, BSc
—Tom Kosatsky, MD, MPH

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This article is the opinion of the BC Centre for Disease Control and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    British Columbia Ministry of Environment. Sea level rise adaptation primer: A toolkit to build adaptive capacity on Canada’s south coasts. 2013. Accessed 15 December 2019. www2.gov.bc.ca/assets/gov/environment/climate-change/adaptation/resources/slr-primer.pdf.

2.    Du W, FitzGerald GJ, Clark M, Hou X. Health impacts of floods. Prehosp Disaster Med 2010;25:265-272.

3.    Munro A, Kovats R, Rubin G, Waite T, et al. Effect of evacuation and displacement on the association between flooding and mental health outcomes: A cross-sectional analysis of UK survey data. Lancet Planet Health 2017;1:e134-e141.

4.    Zhong S, Yang L, Toloo S, et al. The long-term physical and psychological health impacts of flooding: A systematic mapping. Sci Total Environ 2018;626:165-194.

5.    Fraser Basin Council. Lower Mainland flood management strategy. Phase 1 summary report, 2016. Accessed 15 December 2019. www.fraserbasin.bc.ca/_Library/Water_Flood_Strategy/FBC_LMFMS_Phase_1_Report_Web_May_2016.pdf.

6.    UBC Collaborative for Advanced Landscape Planning. Delta-RAC sea level rise adaptation visioning study: Policy report, 2012. Accessed 15 December 2019. www.fraserbasin.bc.ca/_Library/CCAQ_BCRAC/bcrac_delta_visioning-policy_4d.pdf.

7.    BC Ministry of Agriculture and Lands. BC’s food self-reliance: Can BC’s farmers feed our growing population? 2006. Accessed 15 December 2019. https://foodsecurecanada.org/sites/foodsecurecanada.org/files/BCFoodSelfReliance_Report.pdf.

8.    Okanagan Basin Water Board. Groundwater bylaws toolkit. 2009. Accessed 15 December 2019. www.toolkit.bc.ca/sites/default/files/Groundwater%20Bylaws%20Toolkit_0.pdf.

9.    Klassen J, Allen DM. Department of Earth Sciences, Simon Fraser University. Risk of saltwater intrusion in coastal bedrock aquifers: Gulf islands, BC. 2016. Accessed 3 February 2020. www.sfu.ca/grrg/SFU%20Final%20Report%20Risk%20of%20SWI%20Framework_2016.pdf.