Many Canadians encountered unseasonably warm weather last weekend, with temperatures climbing into the mid- to high-20s in various regions of the country, surpassing typical seasonal norms.
Residents headed to beaches in Toronto and Ottawa, an unusual occurrence for early October, as the capital city set a heat record at 29.9 C on Sunday. Montreal also hit 29.9 C on the same day, also breaking a record.
The elevated temperatures are attributed to a significant heat wave in the northern Pacific Ocean, according to experts.
University of British Columbia atmospheric scientist Lualawi Mareshet Admasu explained that the warm ocean temperatures are shifting the jet stream northward. The jet stream, a fast-flowing air current moving west-east across the Northern Hemisphere, acts as a dividing line between cold air to the north and warm air to the south. The connection between ocean heat waves and the jet stream is complex, but Admasu noted that parts of Canada are experiencing “very warm air from southern or Equatorial regions” as it moves north.
Geoff Coulson, a warning preparedness meteorologist at Environment and Climate Change Canada, mentioned that several temperature records were shattered by more than five degrees, an uncommon occurrence as records are typically broken by a fraction of a degree or a degree or two at most.
The ongoing marine heat wave resembles the infamous “blob,” a prolonged period of warm water that significantly impacted marine ecosystems and fisheries along the U.S. and Canadian west coasts from 2013. Studies indicate that global warming is exacerbating and increasing the frequency of marine heat waves, with occurrences every year since 2019 following the “blob.”
The ocean absorbs around 90 percent of the excess heat in the atmosphere, perpetually warming due to greenhouse gas emissions from fossil fuel combustion. This year, temperatures in the northern Pacific are nearly 2.5 degrees warmer than the pre-industrial average, as reported by Berkeley Earth.
Marine heat waves have previously devastated local fisheries, with closures and collapses affecting vital species like Pacific cod and Bering snow crab. William Cheung, from the Institute for the Oceans and Fisheries at the University of British Columbia, emphasized the importance of mitigating climate change to prevent more frequent and intense heat waves in the future.
As temperatures return to seasonal norms with a cold front moving through Ontario and Quebec, experts anticipate a warmer than usual fall in North America due to the persistent impact of the ongoing Pacific heat wave.
