Environment Canada says it can now rapidly link high-heat weather events to climate change

Environment and Climate Change Canada says it's now able to publicly identify links between episodes of extreme heat and climate change within days of a weather event.

The federal department says that its scientists now have the ability to estimate the degree to which human-induced climate change played a role in a heat wave or extreme heat event within a week of it happening.

Friederike Otto, an internationally renowned climate researcher and one of the global leaders in weather attribution science, said Canada's weather service will be the first in the world to issue rapid analyses of heat events.

"The would be the first (meteorological office) who will do this operationally," he said.

"It's about time but it's great that they are doing that."

The science of weather attribution has existed for years. It combines meteorology, weather observation and climate science.

The science does not say whether climate change caused a specific weather event. Rather, it estimates the statistical likelihood of climate change causing a specific weather event and the degree to which it made the event worse. It also can indicate the opposite — that climate change did not play a significant role in a specific weather event.

"It will not answer the question, 'Was this climate change, yes or no,'" Otto told CBC News.

For example, a paper cited by Environment and Climate Change Canada (ECCC) concluded that the heat wave that hit British Columbia, Washington and Oregon in June 2021 would have been 150 times less likely in the absence of human-induced climate change.

The same paper said that in November 2021, human-caused global warming made the extreme rainfall that caused flooding in B.C. about 45 per cent more likely.

ECCC is launching a pilot project which will see its scientists study heat waves in Canada through computer modelling.

The department says it will run computer models on such heat events when they occur to compare two scenarios — one with a heat wave caused by climate change, the other with a heat wave in the absence of climate change.

The department says it is working to expand this system to include extreme cold weather events and extreme precipitation.

Climate attribution science emerged in part from journalists' questions about the links between climate change and specific weather events — questions that climate scientists like Simon Donner of the University of British Columbia have been unable to answer conclusively.