Canadians are facing a "new breed" of storms, and governments should change the way they plan for the kind of wild weather that caused a flash flood in Burlington, Ont., on Monday, says Dave Phillips, Environment Canada's senior climatologist.
'It's like these are bulls-eyes.'—Dave Phillips, senior climatologist, Environment Canada, about intense local storms
"These [once in] 50-year floods are occurring every 10 years, because our climate has changed," he said.
Phillips added that planning for weather based on the past 100 years "masks" recent events that have dramatically changed how much rain falls. He said in the aftermath of the Toronto floods of August 2013, a look into the last 25 years of rainfall showed that there were three 100-year storms, and six 50-year storms.
CBC meteorologist Shelly James said that Monday's flash flood was an extremely isolated event, with 190 mm of rain in Burlington, but nearly no rain on either side of the city, including next to none in nearby Hamilton.
Phillips said that in the past few decades, precipitation across Canada has increased 12 per cent, and the "predictable" storms of the past, which used to sweep across southern Ontario, have transformed into "little cells that affect a neighbourhood, a small area."
"It's like these are bull's-eyes," Phillips said.
'No infrastructure around that could handle' Burlington rainfall
Dan McKinnon, the City of Hamilton's director of water and watershed operations, said his department is well aware of the change in weather, but the challenge is how to deal with it.
"So what do we design for?" asked McKinnon. He said the city is looking at porous pavements, green roofs and constructing storm water management systems to handle large storms. But there's no rate or amount of precipitation the city could "blanket" plan for and apply to building codes and future infrastructure projects across the city.
McKinnon added that various parts of the city have different pavement and green space areas that can help soak up flash floods and major rains.
Although Phillips admitted there was no amount of affordable infrastructure that could have prevented Monday's flooding in Burlington, the result of nearly two months' worth of rainfall in some 2½ hours, he said planning needs to be updated to accommodate climate change.
"The kind of storm that you saw on Monday, there's no infrastructure around that could handle that," Phillips said. "We accept the fact that we're going to be flooded out. That one was so off the scale."
"The reality is that our infrastructure is aging, it's breaking down.… We need to take into consideration the new climate," Phillips said.
"Because of climate change it could very well be that the performance of our infrastructure is not living up to what it was designed for."