Vancouver Under Climate Change Gun

Vancouverites and the region's masses of visitors might have to kiss Granville Island and other attractions goodbye.   Sea level rise is estimated to reach 80 cms. in Nanaimo on Vancouver Island and upwards of 120 cms. in the Lower Mainland's Fraser River estuary by 2100.

Sea level rise sounds far more benign than it is.   For those rising seas exact a number of impacts from salination of freshwater reserves to erosion and flooding, particularly through stronger storm surge events.

Andrew Yan, a planner and researcher with Bing Thom Architects, estimates the city will have to spend upwards of $510 million to build and upgrade the dikes and seawalls - plus billions more to buy the land to put them on - over the next century.

"What's under threat in Vancouver is a lot of our identity; our beaches, our seawall ... this is what makes Vancouver such a livable place," Yan said. "We just need to look at Granville Island and its exposure to sea level rise and what may be required to defend it."

Richmond’s Steveston, which has experienced huge residential growth along its waterfront in recent years, will face significant pressures in the future, Yan said, while south Surrey’s Crescent Beach is already being threatened by a more insidious force: increasing groundwater from rising ocean tides.

“It affects every municipality that touches the water,” Yan said.

“Sea level rise isn’t going to separate itself from the boundaries of Vancouver, Burnaby, Richmond or Surrey. We’d better be serious about this. It’s important to plan now as opposed to 50 or 70 years from now.”

...Deborah Harford, executive director of Simon Fraser University’s Adaptation to Climate Change Team, noted all of Metro Vancouver is ranked as at high risk for negative effects of climate change because it has so many people, so much infrastructure and so many assets at sea level. And with the region built on river deltas, she said, there’s also risk of the sea encroaching toward the area’s rivers, leading to “salt wedging” or salination of the region’s agricultural lands and the water supply.

These reports appear confined to basic sea level rise, of itself a Herculean challenge.   The problem for the Lower Mainland, however, is more complex yet.   A warming atmosphere is triggering early Spring melt of the local mountain snowpack which triggers flooding in the Fraser estuary river system where already low-lying communities are put at risk.  Rising seas will only back up that meltwater, adding to the flooding.  

And then there's the subsidence factor.   A lot of the communities of the Lower Mainland are already below sea level, the ocean held back by dykes.   Constructing homes and buildings is a complicated process of pre-loading where mountains of soil or sand are heaped in place to cause the spongy soil to compact enough that it will bear the weight of construction.   After a suitable interval the preload is trucked away and construction ensues.   However that never really ends the subsidence which slowly continues, increasing the amount the property is below sea level.   Rising sea levels mean burning the candle at both ends.   Adding snowpack meltwater flooding to that only worsens the situation.

And then, there's the Big One, the inevitable earthquake that's expected to rock coastal British Columbia some time between this afternoon and a century from now.

Two separate geological studies released this week suggest the earthquake hazard in the transboundary region of the Pacific Coast of North America — including southern British Columbia — is significantly greater than previously believed, with both teams of U.S. scientists urging heightened readiness throughout the region for a future offshore “megathrust” event that could compare with the one that triggered Japan’s earthquake-tsunami-nuclear catastrophe last year.

In one study, a 13-year, comprehensive analysis of the Cascadia earthquake-prone zone between Vancouver Island and Northern California, a team of researchers led by Oregon State University earth scientist Chris Goldfinger concluded that the “clock is ticking” ahead of a potentially devastating earthquake in the region within the next 50 years.

The second study, which appears in the latest issue of the journal Geology, interprets new fault-zone temperature data along the Pacific Coast to conclude that the probable impact area of the next megathrust quake in the region could extend as much as 55 kilometres farther east than previous studies have suggested — raising the spectre that coastal cities such as Vancouver, Victoria, Seattle and Portland would experience significantly greater-than-expected seismic impacts when the next “Big One” strikes.

“If one is closer to the rupture area of an earthquake, then the ground shaking will be more intense, all other things being equal,” study co-author Glenn Spinelli, a research scientist with the New Mexico Institute of Mining and Technology, told Postmedia News. “Therefore, if the rupture area of a Cascadia subduction zone earthquake is closer to land, then the shaking on land will be greater.”

And what happens when already boggy, below-sea-level lands are hit by a major earthquake?   This is what happens when the land beneath your feet - and your house - turns to porridge.