British Columbia

Risk of landslides in North Shore region could quadruple by 2080s, study suggests

Metro Vancouver’s North Shore region could see a 300 per cent increase in landslide risk by the 2080s, a new study suggests.

Landslides will also become more intense due to the effects of climate change

A landslide in North Vancouver in January 2005 swept two homes down an embankment, killing one woman. A study suggests the landslide risk in the area could quadruple in the next five decades. (CBC)

Metro Vancouver's North Shore region could see a 300 per cent increase in the risk of landslides by the 2080s, a new study suggests.

The study, published in the Geomorphology journal, used mathematical models to predict how increasing temperatures due to climate change would affect precipitation and by extension landslides due to rainfall.

'Shallow landslides,' which can be half a metre to a metre deep, occur due to rainfall saturating forest floors, causing the soil to detach. 

The study says landslides in the North Shore will also be much more intense in the coming years, with models showing a 20 per cent to 50 per cent increase in magnitude.

"It is something that doesn't happen overnight, and we can prepare ourselves," said study author Matthias Jakob, principal geoscientist at BGC Engineering.

"We can prepare ourselves through structures, land use zoning, building covenants, [and] perhaps sterilizing certain lands that are in high-hazard areas."

The North Shore has seen numerous landslides over the years, with one in 2005 killing a 43-year-old woman.

Jakob says the region has taken proactive steps to mitigate the risk of landslides since then, and the public does not need to panic.

He says planners should systematically identify hazards, take into account climate risks and protect existing homes with appropriate structures.

"I can't say that the future is rosy. But that shouldn't paralyze us."

Increasing risk of after-effects from catastrophic events

Jakob built his study on his earlier 2009 study which showed a 10 per cent increase in the risk of landslides by the end of the 21st century.

This year, using updated climate change models, he re-did the study. Both studies used Metro Vancouver's landslide database, with data dating back to 1981.

Although Jakob's study focused on shallow landslides and show increasing heat triggering more intense landslides in the North Shore, he says regions around the province are now reckoning with the aftermath of catastrophic climate events like wildfires and heat waves.

A burnt hillside after a wildfire near Monte Lake, B.C. Jakob says people living in areas affected by wildfires could be at risk of further adverse weather events. (Maggie MacPherson/CBC)

"In the aftermath of these forest fires, so-called post-fire debris flows become much more prevalent," he said. 

According to Jakob, though people can live in areas after wildfires are extinguished, they are at risk of landslides or worse when rains start again.

He says communities, infrastructure developers, and governments should be prepared to deal with catastrophic weather events and their aftermath throughout the province.

"I have hope that the COP26 meeting will ratify some incredibly stark emission reductions and so on and so forth," he said. "But we've known these problems for decades."

With files from Megan Stewart

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