Sun, smog, and snow: climate-heating El Niño’s impact on Canadian summer

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By Isabelle Mailloux Pulkinghorn

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Canadian Summer: Sun, smog, and snow

Explainer – Climate-heating El Niño’s impact in Canada

From 30 degree Celsius to 30 cm of snow. Recent weather forecasts in Canada have included heat domes, tornado alerts, smog, severe thunderstorms, and… snow! Aside from the effects of climate change, these extreme weather patterns may be explained by El Niño.

We sat down with professor Hossein Bonakdari, Associate professor of Civil Engineering (climate change, artificial intelligence modelling, design of climate change resilient water infrastructures), in the university of Ottawa’s Faculty of Engineering, to learn more.

Question: Professor Bonakdari, please explain what is El Niño?

Hossein Bonakdari - El Niño is a naturally occurring event, characterized by the warming of the Pacific Ocean. It has far-reaching consequences on weather patterns worldwide and is expected to persist for several years. Using climate prediction models, powered by artificial intelligence, we have been able to study its impact in Canada, when coupled with climate change.  

The annual mean global near-surface temperature for each year between 2023 and 2027 is predicted to be between 1.1°C and 1.8°C higher than the 1850-1900 average.

North America will experience diverse weather patterns (temperature fluctuations, precipitation anomalies, forest fires, severe weather events and disrupted ecosystems) due to the strong onset of an El Niño event, while Europe is trending towards high-pressure atmospheric blocking (high temperatures, or dry conditions, heatwaves, and reduced precipitations).

Q. How will it specifically impact Canada?
H.B. – ThisEl Niño event will impact us a few different ways.

  1. Temperature Anomalies : El Niño has been linked to both milder and colder winter temperatures across Canada. Coastal areas such as British Columbia and the Atlantic provinces often experience milder winters during El Niño events. Conversely, the Prairie provinces and northern regions may encounter colder conditions due to altered atmospheric circulation patterns.
  1. Precipitation Patterns : El Niño exerts a substantial influence on precipitation distribution throughout Canada. While it tends to bring increased rainfall to the southern regions of British Columbia, Alberta, and parts of the Atlantic provinces, other areas like the Yukon, Northwest Territories, and northern Quebec often witness drier conditions during El Niño events. These shifts in precipitation patterns can impact water availability, agriculture, and increase forest fire risks, as we have observed.
  1. Winter Storm Intensity : El Niño can also impact the intensity of winter storms in Canada. Coastal regions, particularly the Pacific coast, may experience more frequent and intense storms during El Niño periods. This can result in heightened risks of coastal erosion, flooding, and severe weather events, emphasizing the importance of preparedness and infrastructure resilience. And this explains the snow that fell in Alberta late last month.
  1. Ecosystem Dynamics : The ecological consequences of El Niño extend beyond weather patterns. Marine ecosystems off the coast of British Columbia, for instance, may witness changes in nutrient availability, affecting fish populations and marine food webs. Inland regions can experience disruptions in migratory patterns and breeding cycles of wildlife due to alterations in temperature and food availability.
  1. Wildfire Frequency and Severity: El Niño can also have a significant impact on wildfire activity across various parts of the country. The warmer temperatures associated with El Niño can create conditions that enhance atmospheric instability, leading to increased upward motion of air masses. This heightened vertical motion promotes the formation of thunderstorms, which are known to be the primary generators of lightning. During El Niño events, areas that are already prone to wildfires, such as British Columbia and parts of the Prairie provinces, may experience a higher frequency and increased severity of wildfires. The combination of dry vegetation, strong winds, and the ignition source provided by lightning strikes can contribute to the rapid spread of wildfires in these regions.

     

Q. How long do they usually last?

H.B. - It is believed that there have been at least 30 El Niño events since 1900. The duration of El Niño events can vary, and there is no fixed timeframe for how long they typically last in Canada. The most recent important El Niño event in Canada occurred from late 2015 to early 2016. It lasted for approximately 12 months, with its peak intensity observed during the winter of 2015-2016. The winter of 2015-2016 (December-January-February) was one to five degrees Celsius warmer than normal in all provinces, with particularly unseasonable warmth in Quebec, the central Prairies, and Yukon. Following that, the spring of 2016 remained warmer than normal in Western Canada and the Prairies. But the last El Niño event took place between February and August 2019 and its impact was relatively weak. On average these events last between 9-12 months. The longest El Niño event thus far took place in 1986 and lasted 18 months. One thing is certain. We will see a mixed bag of weather events across Canada until El Niño leaves us.

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Associate Professor, Department of  Civil Engineering, Faculty of Engineering

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