The severe rainfall events that occur on Canada’s Atlantic and Pacific coasts are a glimpse into the country’s climate future, experts say.
However, the impact of such extreme weather, such as the massive flooding in British Columbia, can be managed if world leaders are able to limit climate change.
“A new normal is coming. … This is a glimpse into the future, ”said Kent Moore, professor of atmospheric physics at the University of Toronto.
“We are seeing the effects of all the warming that has happened in the last century and we are going to continue warming.”
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This week, communities along the Atlantic and Pacific coasts of Canada are facing heavy rains from two “atmospheric river” storms, which are giant bands of water vapor in the sky that can be several hundred kilometers long.
On the east coast, strong winds and heavy rains hit the Canadian Atlantic as part of a storm system advancing from the Caribbean.
Some areas, like the port of Halifax, have seen wind gusts of up to 107 km / h. Rain totals have exceeded 50 millimeters in several maritime communities, and those numbers are expected to rise.
Environment Canada has said that 100-150mm of rain could fall in eastern Nova Scotia and Cape Breton, while southwest Newfoundland could receive up to 300mm of rain in the next two days.
Meanwhile, off the west coast, parts of British Columbia will see multiple storms that could bring 100 to 200mm of rain across central and northern British Columbia, Global News chief meteorologist Anthony Farnell said.
That system, which is expected to begin late Wednesday, will move south and could drop up to 100mm of rain in parts of the province that are still recovering from severe flooding caused by a deluge of rain just barely. last week, Farnell said.
“The soil is still saturated, and that’s the concern, that these incredible amounts of rainfall are no longer needed to cause additional flooding,” he said.
“Also, many of the levee systems there, the pumping stations, have been weakened. So if you get another atmospheric river or another one of these storm parades, you’re going to have problems again. “
While these so-called atmospheric rivers are nothing new, particularly for the West Coast, the size and repeatability of them is what worries experts.
Atmospheric rivers and changing weather
Last week, an atmospheric river hit southern British Columbia, causing flooding, landslides and landslides that damaged roads, prompted evacuations and isolated thousands of people.
Typically, the west coast could see 20 to 30 atmospheric rivers on average in the fall and winter, said Armel Castellan, a warning preparation meteorologist for Environment Canada.
Also, at any time in the world, there can be between four and five atmospheric rivers. But the gravity of these atmospheric rivers is changing.
Castellan said that some atmospheric rivers hold more water and, as a result, the weather event could last longer. He said the trend is “consistent with climate change.”
“When it becomes a 48 hour or longer event, or even a 36 hour event, it can be very damaging depending on the rainfall rates; then you start looking for atmospheric rivers that are not only beneficial to the ecosystem, but are absolutely devastating, “he said.
“We know that humidity in the atmosphere rises as a result of the post-industrial warming of the baseline climate, so it can add more moisture to the flow and that creates atmospheric rivers that are more powerful on their own. “
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Farnell said that while it’s difficult to blame climate change for a specific event, past weather systems show extreme events are becoming more common.
The coastal regions of Canada will be among the first to experience the effects, he added.
“One similarity is that with warmer weather, even a one or two degree rise over such a large ocean adds an incredible amount of energy and water vapor to these systems, so you’ll see 20-30% more. of rain. and the first areas to feel the effects are those areas, ”Farnell said.
“The floods that happened last week, those happen during our lifetime. But when you start to see the amount of events piling up, not just in Canada but in other parts of the world, you take a step back and wonder … what’s going on? ”.
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In 2019, the Council of Canadian Academies concluded that Canada’s coasts are among the regions facing the greatest risks from climate change.
Climate change is causing sea levels to rise gradually, making flooding more common and storm surge heavier and more powerful, according to the report.
Infrastructure was also a concern, as heavy rains, floods, and high winds are growing threats to buildings, such as homes and hospitals.
Although the coasts of Canada are at risk of severe weather, climate change is not limited to a few provinces or territories.
“In the GTA in recent summers, we have had very heavy rains that have overloaded the storm sewer system and the basements have been flooded,” he said.
“Every part of the country is experiencing the impact of climate change and it is different depending on where you are.”
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Moore added that it is up to world leaders to manage climate change to control how severe weather events will be.
“If we increase (temperatures) by the end of the century … it will really determine the intensity of events in the future,” he said.
“The most intense they are going to get is under our control.”
– with archives of The Canadian Press.
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