British Columbia

National climate change report warns of risk of storm surges on B.C.'s coast

Report on climate change impacts on Canada's coast also warns of marine ecosystems and salmon runs being affected in B.C.

Report on climate change's impact on Canada's coast also warns of marine ecosystems and salmon being affected

Waves pound the shore in White Rock in March of this year. (Bill Hawke)

Flooding from storm-surges — an abnormal rise of sea water generated by a storm — is a greater threat to communities along B.C.'s coast than the rising sea level alone.

That is one of the findings from Canada's Marine Coasts in a Changing Climate, a new national report from Natural Resources Canada exploring the impacts of climate change on Canada's coasts.  

Nathan Vadeboncoeur, the lead author of the West Coast chapter of the report, said that the height of waves is related to water depth, so as the sea level rises the waves generated during a storm are going to be higher and more powerful.

"Imagine a sea-level rise of 50 centimetres. But now imagine a two-meter wave on top of that. The 50 cm sea level rise gets your pants wet, but the two-metre wave is going to knock you over and it's going to cause damage," said Vadeboncoeur, a former University of B.C. researcher and the president of Vadeboncoeur Consulting.

Effect of storm surges

"When you combine that with more frequent and intense storms, it exposes our coastal landscapes to the kinds of beatings that they didn't used to get nearly as often.

"The reason that the report highlights that it's storm surge and not only sea level rise that's important is because sea level rise gets a lot of attention, whereas storm surge is very local. And climate change is a global problem with a very local impact."

During a storm in December 2014, the Puntledge River overflowed its banks and flooded campsites at the Puntledge RV Campground and Nim Nim Interpretive Centre in Courtenay, B.C. (Gary Graves, CBC News)

The report's key findings for the West Coast region also states marine ecosystems will be affected as the ocean warms and southern species move northward into B.C. waters and warns increased river temperatures could affect the timing of salmon runs.

The findings also state that sea-level rise will not affect all areas of the B.C. coast equally, and that the largest amounts of relative sea-level rise are expected to occur in parts of the Lower Mainland such as Langley, Surrey and Delta, as well as southern Vancouver Island and the North Coast.

Report says B.C. is preparing

The report says local governments have been making progress on adapting to climate change and highlights projects such as the cost assessment for upgrading Metro Vancouver's dike system that is currently underway and the placement of boulders below the low-tide level off the West Vancouver shore to buffer against the impact of storm surges.

Vadeboncoeur said information needs to be continually gathered so that communities can plan for the impacts of climate change.

"We can say generally how bad it will be," he said.

"What we need are the studies that are going to show the specific impacts at a very, very fine scale, so we can use these to inform engineering reports and zoning documents and policies to actually have a strong empirical basis for realigning the built environment around these coastal risks."

With files from CBC's B.C. Almanac


To hear the full story listen to the audio labelled: National climate change report warns of risk of storm surges on B.C.'s coast

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