For the first time, the Canadian government conducted a rapid analysis of a period of extreme heat and determined its connection to human-caused climate change.

The analysis conducted by Environment and Climate Change Canada (ECCC) found that the heatwave in Ontario, Quebec, and Atlantic Canada from June 17 to 20 became two to ten times more likely due to climate change.

Greg Flato, a senior research scientist at Environment and Climate Change Canada, said at a press conference: "Across all regions, the event has become more likely due to human influence on the climate."

The analysis indicated that unusually high daytime temperatures, high humidity, and warmer-than-usual nighttime lows were observed. Both Bathurst and Saint John, New South Wales, in particular, recorded all-time highs since data collection began in the 1870s.

The ECCC study is the beginning of an experimental project, where researchers will analyze weather data and simulate climate models to compare how these types of events have changed between today's climate and the cooler pre-industrial climate.

Flato mentioned that the ongoing heatwave in Western Canada will also be analyzed, as well as others in the future, adding that management will expand this system to analyze other severe weather events. An ECCC official stated that their rapid attribution system relies on peer-reviewed techniques.

"It is not just a one-off study."

These findings contribute to a growing research field known as rapid attribution, where scientists use models to quickly determine the connection between climate change and an extreme weather event, such as heatwaves, floods, and storms.

Frederik Otto, co-founder of the World Weather Attribution (WWA) group, which is based in the UK and conducts attribution studies, stated that the federal government's commitment to continuous attribution represents "a really important development."

"When you don’t just have a one-off study, but make it a regular practice, it’s clear that this helps understand not just how things have changed, but how quickly things are changing."

Otto noted that other countries have conducted attribution studies, but Canada seems to be the first to commit to doing it continuously.

Attribution studies do not definitively determine whether climate change caused a specific weather event, but indicate the statistical likelihood that climate change influenced the occurrence of a specific weather event and how it intensified. (In some cases, natural weather patterns, such as El Niño, also play a role in elevating temperatures).

Otto added that the conclusions can help governments make better decisions, such as planting trees in particularly hot parts of the city or ensuring vulnerable populations have access to cool spaces.

"If you know that the heatwave you are experiencing now is not just bad luck for nature, but is actually something... you expect to see every 10 years or so, it means you have, as Otto said, "an infrastructure that can handle these levels of heat."

In the past, WWA determined that climate change has more than doubled the likelihood of the conditions that led to the record wildfire season in Quebec, and estimated that the devastating heat dome in Western Canada in 2021 would occur every five to ten years in a 2-degree Celsius warmer world.

WWA stated that such studies are not subject to immediate peer review and are not published in scientific journals due to efforts to disseminate information shortly after an event, but rely on peer-reviewed modeling techniques - with many ultimately being published.

"A way to elevate the conversation."

Sarah Henderson, the scientific director of environmental health services at the British Columbia Centre for Disease Control, stated that this type of study "can reinforce the message that climate change is affecting the health and well-being of Canadians right now."

She said: "It is just working to put these events into the context of climate change for the public and for public health officials."

"It is a tool to elevate the conversation and ensure that climate change is never excluded from the discussion about rising extreme temperatures."