Canada launches new extreme weather event attribution system

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Remember that heat wave in June? Spring wasn’t even officially over yet, but we were already sweating profusely.

Scientists from Environment and Climate Change Canada say extreme weather Hail events that strike eastern Ontario, Quebec and the Atlantic provinces are two to ten times more likely to occur in modern times than in pre-industrial times due to human-induced climate change.

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ECCC scientists held a technical briefing on Tuesday to introduce their new “Rapid Attribution System for Extreme Weather EventsThe prototype system allows researchers to compare past and present climate simulations and reveal how human-caused climate change affects the likelihood and intensity of extreme weather events. weather event.

“Climate change is not just something to be expected in the future,” said Gregory Flato, director of climate research at ECCC. “It’s something we are experiencing right now. The Rapid Event Attribution System allows us to immediately quantify how extreme events, in this case extreme heat waves, are changing due to human-caused climate change.”

“By showing and calculating the increased likelihood of events like these that we’ve already experienced, I hope it will provide Canadians with a more compelling message about the role of climate change, how it’s impacted our lives and our environment, and how it will continue to impact us. … The warmer the climate gets, the more likely these types of extreme temperature events will occur. By providing this information right after the event, we hope it will drive home the point that climate change is impacting us now and will continue to impact us in the future.”

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Daily maximum temperatures were well above normal for this time of year from June 17 to 20, with more than 200 daily maximum temperature records in Ontario, Quebec and the Atlantic provinces. The heat wave was accompanied by extremely high humidity, and nighttime temperatures did little to alleviate the heat.

“It is rare to see such a heatwave this early in June, and our attribution analysis shows that the likelihood of such a heatwave has increased significantly due to the impacts of human-caused climate change,” Flato said.

The prototype system is part of Canada’s recently funded National Adaptation Strategy and has been operational since April. Canada is one of the first countries in the world to use such a system, and the June heatwave was the first major event to share results.

Attribution of extreme weather events was done using two sets of computer simulations of the global climate system, one representing the climate of the 19th century, before human activities significantly altered the climate, and the second using present-day climate conditions, including greenhouse gas levels and other changes that affect climate, Flato said.

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“By carefully analyzing the differences between these simulated climates, we can calculate how likely human-caused climate change would have made the observed events.”

The system allows researchers to characterize the extent to which extreme weather events are becoming more frequent and more intense due to climate change. While this has been possible in the past, these analyses used to take months to complete. With the new system, it only takes days.

this ECCC website Seven different clearly defined terms will be used to describe how likely or unlikely an extreme event would be in the absence of human-caused climate change:

• “More likely” (meaning at least 10 times more likely);
• “more likely” (at least two to ten times more likely);
• “More likely” (at least one to two times more likely);
• “There is no evidence of an attributable change in likelihood”;
• “unlikely” (at least one to two times less likely);
• “very unlikely” (at least two to ten times less likely);
• “Extremely unlikely” (at least 10 times less likely).

Over time, ECCC researchers will compile a catalogue of these extreme weather events, which will provide valuable information on the extent to which heat waves and other extreme weather events are becoming more frequent and more intense.

“This information will aid adaptation planning and decision-making to ensure we are prepared for future climate,” Flato said.

By next winter, the ECCC will use the system to analyze the likelihood that extreme cold snaps or unusually warm winter weather are caused by human-caused climate change, and by next year, they hope to be able to use the system to analyze extreme precipitation.

As evidence mounts about the frequency and magnitude of these events and why they occur, policymakers can take smart steps to protect the public and the environment, whether through new building code requirements to prevent floods and fires or stronger carbon emissions policies, Fratto said.

mlalonde@postmedia.com

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