Climate change: Rising oceans, storm surges « disaster in slow motion » for the coasts

The tides are rising, the sands are shifting and the coasts are crumbling. As studies warn of rising seas and accelerating erosion as a result of climate change, Canada’s coastal communities are wondering what the future holds.

“Living on the coast is part of our economic, social and cultural fabric. It’s people’s livelihood. It’s hard to leave these shores,” said Chris Houser, a professor of environmental science at the University of Windsor and a member of the school’s coastal research group. « It will be a very difficult time as we see some of these coastal areas being eroded or even more affected by sea level rise and storms. »

Communities on Canada’s east and west coasts are at risk of slipping under rising tides as water levels rise. A report by the Intergovernmental Panel on Climate Change released last year says the rate of sea level rise is accelerating and seas have risen about 20 centimeters since the start of the 20th century. century.

John Clague, professor of earth sciences at Simon Fraser University in Burnaby, British Columbia, said even a few millimeters make a difference, especially when the effects are exacerbated by severe storms like Fiona which hit Canada Atlantic in September.

« It’s a disaster in slow motion, » he said. He noted that Fiona was producing a lot of erosion. “And it’s permanent. Once it’s done, it’s done. »

On the other side of the country, municipalities like Richmond, British Columbia, with a population of more than a quarter of a million people, live with a “threat at their doorstep,” he said. The region is home to Deltaport, one of Canada’s most important export facilities, as well as Vancouver International Airport and trillions of other critical infrastructure that cannot easily be abandoned or relocated, a- he declared.

The most immediate solution implemented is for new buildings along the shore to be raised a meter to account for expected sea level rise, he said, but this is a a temporary solution.

« We’re just throwing the problem down the road, » Clague said.

Houser said scientists didn’t have a « good calculation » of how much land was lost as sea levels rose because a combination of factors were involved. While rising waters are claiming land, he added there is also an additional threat of flooding and erosion.

“Much of the erosion in Canada has nothing to do with sea level rise. But it really has to do with sediment imbalance,” he said.

When the seas come in, the ecosystem adapts by moving landward. As long as there’s space to move around, that’s fine, Houser said, but human communities aren’t that mobile. People could start abandoning coastal communities affected by changing conditions, he said.

A study published in March 2020 by the European Commission’s Joint Research Center indicates that nearly half of the world’s sandy beaches are at risk of disappearing by the end of the century due to rising greenhouse gas emissions. Greenhouse.

Australia stands to lose the most, followed closely by Canada, the document suggests. Models show that Canada is expected to lose between 6,400 and 14,400 kilometers of sandy beach by 2100. Canada’s total coastline is approximately 243,000 kilometres.

Adam Fenech, director of the climate laboratory at the University of Prince Edward Island, said the province’s 1,260-kilometre coastline is at significant risk of erosion. Studies have shown that the island experienced erosion at a global average rate of 0.28 meters per year between 1968 and 2010.

Fenech used this data to show changes in the province’s coastline over the next 80 years. His calculations show that more than 1,000 homes, 146 commercial buildings, more than 40 garages, eight barns, seven gazebos, 17 lighthouses and 45 kilometers of road are at risk of being lost to coastal erosion by the end of the century.

The island is « just made up » of sand and sandstone, and isn’t a « very rugged » place to start, Fenech said. Adding climate change makes things worse.

« Sea levels are rising, water temperatures are rising by shedding sea ice, which acts as a good buffer against storm activity. We’ve had stronger storms, so it all works against the Prince Edward Island in terms of its future as an island now,” he said.

“The island isn’t going anywhere fast. It would take another 10,000 years for the island to disappear. But there are places where we lose one to five meters of coastline per year. »

Professor Kate Sherren of Dalhousie University’s School of Environmental Studies said the edges of Canada were higher and drier before the glaciers retreated.

Geological forces are still rebalancing from this weight, and coastal edges are slowly slipping through the water, she said.

Imagine a heavy person sitting in the middle of a waterbed with two smaller people on either end, Sherren said. « When this big person gets up, people at the end will actually come down. »

And that’s what’s happening in central Canada in this post-glacial period, she says.

Fenech called PEI. the proverbial canary in the coal mine in terms of being at the forefront of the impacts of climate change. But it also helps scientists and governments understand where and what are the best ways to adapt to and live with climate change, he said.

Houser said coastal communities affected by major storms will have to rethink how they rebuild and whether certain areas have become off-limits.

“Are we going to impose another type of construction and armoring of the coast? Or will we…allow this area to be claimed by water?

When Hurricane Ivan hit the Florida coast in 2004, it was considered a 100-year storm, he said.

“What happened was right after the hurricane – after all the houses were demolished, after the roads were completely torn up – house prices actually went up. The number of constructions increased because people thought they were safe for another 99 years,” he said.

“There is a problem in the way people perceive and understand science, understand probability. It’s even harder to translate when the frequency and magnitude of storms actually change.

Erosion events seen in Prince Edward Island and Northumberland, Nova Scotia this year after Fiona arrived in the region show they will drastically change the landscape, Sherren said.

“Maybe it won’t go away in 20 years, but it’s going to be very different. And that’s the term of a mortgage.

People need to understand that coasts are dynamic, not static, she said.

“The floodplain belongs to the river and the beach belongs to the ocean,” Sherren said, recalling a quote she once heard. “They don’t belong to us. And they can pick it up whenever they want.

This report from The Canadian Press was first published on November 20, 2022.

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