A new, first-of-its-kind analysis suggests that the record heat wave that hit eastern Canada last month was made much more likely by human-caused climate change.
Environment and Climate Change Canada says the results of its rapid analysis of the mid-June heat wave in parts of Ontario, Quebec and Atlantic Canada show it has become two to 10 times more likely due to climate change.
It’s the public launch of Canada’s new pilot project for rapid attribution of extreme weather events, which officials say can determine whether and to what extent climate change has made a specific heat event more likely.
Environment and Climate Change Canada is considered one of the first government offices in the world to publicly deploy a rapid attribution tool and apply it automatically across the country, with results prepared within days.
Federal officials say they eventually plan to apply the program to other extreme weather events, such as precipitation, and that work is underway to expand it to wildfires as well.
Scientists say attribution studies can inject climate science into public debates about specific extreme weather events when it is most relevant, while highlighting the effects of emissions on global warming.
Hundreds of attribution studies have been published over the past two decades, largely following the same general principle.
The researchers run climate models under two scenarios, one based on a simulation of a pre-industrial climate and one based on a simulation of the current climate. They then compare the results to an observed heat wave to determine how much it was influenced by human-caused global warming.
World Weather Attribution, which is comprised of a team of international researchers, has been at the forefront of rapid attribution science, collaborating with local scientists, including those at Environment Canada, on dozens of studies over the past decade that have helped standardize research practices.
Shortly after Mexico’s heat wave ended last month, the group released a report suggesting it was 35 times more likely and about 1.4 degrees warmer due to climate change.
The analysis follows new findings showing that June marked the 13the consecutive month of record global temperatures. This is also the 12the consecutive month where temperatures were 1.5°C higher than in pre-industrial times, according to results published this month by the European climate agency Copernicus.
The 1.5C mark is also the limit on warming agreed to by countries under the 2015 Paris climate agreement, although scientists note that it will not be considered crossed until there is a longer duration above that threshold, up to 20 or 30 years.