BC’s Ministry of the Environment released a report on sea level rise adaptation over the weekend. It is inevitable that Metro Vancouver municipalities will come to restrict new development and abandon at-risk areas to protect homes, infrastructure and agricultural land from the higher, warmer sea.
Compared to other provinces, BC:
has the lowest proportion of its land area at risk but the majority of [Canadian] dwellings at risk, due to the high housing density in the Lower Mainland, much of which is low lying. The Lower Mainland, consisting of Metro Vancouver and the lower Fraser River Valley, is very vulnerable to sea level rise because of a 127 kilometre system of dikes, which were not built with sea-level level rise factored into the design. This area also has very expensive real estate subject to flood risks.
The report looks at two responses for our coastal areas: climate-related development planning and strategic retreat.
The first means no new construction would be permitted in high risk areas. The latter strategy means a gradual abandonment of these areas. Citing the now-shuttered National Round Table on the Environment and the Economy, the study notes strategic retreat produces significant benefits over development planning. In some areas, dikes would need to be 6–8 metres high to protect dwellings, much taller than current structures.
A storm surge and a high tide have forced officials to close parts of the seawall in Vancouver’s Stanley Park and the seawalk in West Vancouver…
“Gates have been closed between these sections of the seawall to ensure public safety. The seawall is expected to reopen later today when the tides recede. Users are urged to exercise caution on all sections of the seawall in Vancouver during these conditions.”
“When you look at the value of the community and the built environment in a place like Richmond, the expenditure required to meet this challenge is really quite low. It’s really a bit of a no-brainer that you can do it,” [the director] said, adding that in today’s dollars, the cost to build up the dike would be $200 million to $300 million.
What’s two or three hundred million dollars between friends?
Global warming-induced sea level rise means major upgrades are needed to Metro Vancouver’s flood defence network over the next several decades. A new report from the BC government, Cost of Adaptation — Sea Dikes and Alternative Strategies, estimes the costs could total $9.5 billion dollars.
“Managed retreat” — where properties are returned to a “natural” or low-value state and allowed to flood — is included as an option. In almost all cases, staff rejected this possibility.
“In an OECD (Organization for Economic Co-operation and Development) report, Vancouver is rated 15th (in the world) for exposed assets, with $55 billion at risk, and 32nd in terms of population at risk, with 320,000 people exposed,” CCAR says, listing the infrastructure at risk in Vancouver as highways, sewer systems, waste treatment facilities, shipping and ferry terminals and the airport.
Farmland, residential and industrial areas would be at risk, and about 220,000 of the 320,000 people at risk in the area live at or below sea level, protected by 127 kilometres of dikes that were not built to withstand sea level rise.
Retreat, of course, is no one’s first choice. But adapting means committing fully to the New Orleans model. It means potentially thousands of miles of levees and floodwalls across much of the East Coast. And that’s just to handle the rising sea.
If we choose to remain on the coasts, big tasks await us.
The most significant identified risk was intensified and more prolonged heat waves, compounded by an aging and more vulnerable population. Risks to buildings and infrastructure from sea level rise and more frequent and intense storms were also highlighted.
The report warns of a nearly one metre sea level rise risk by 2100; hotter, more humid days; drier summers and wetter winters, and higher tides in winter that worsen storm surges.
The risk assessment will inform a community-wide climate change adaptation plan arriving this fall.
The science is clear: our global climate is changing. Despite all efforts to reduce greenhouse gas emissions, we will continue to experience weather events and impacts related to climate change over the coming decades, even if all emissions were stopped today. The climate change adaptation plan will help our community understand and prepare for the opportunities and risks we face from a changing climate.
Reuters reports that new research on the thermal expansion of sea water suggests sea level rise is unavoidable:
“Even with aggressive mitigation measures that limit global warming to less than 2 degrees above pre-industrial values by 2100, and with decreases of global temperature in the 22nd and 23rd centuries … sea level continues to rise after 2100″.
This is because as warmer temperatures penetrate deep into the sea, the water warms and expands as the heat mixes through different ocean regions…
“Though sea-level rise cannot be stopped for at least the next several hundred years, with aggressive mitigation it can be slowed down, and this would buy time for adaptation measures to be adopted,” the scientists added.