After bringing a warmer, drier winter to much of Canada, the El Niño weather event that has gripped the Pacific Ocean and subsequently the world may at last be over.
But scientists say its effects could still linger over Canada before the cooler La Niña likely takes effect.
“It’s like a teeter-totter going up and down; El Niño was going to end at some point in time,” University of Toronto Mississauga atmospheric physics professor Kent Moore said.
“Then later, in the summer and into the fall La Niña will start…. The unknown is how extreme it’s going to be.”
El Niño is known for warm, above-average sea-surface temperatures in the Pacific Ocean, while La Niña tends to occur after, bringing colder effects. But while both events occur in the Pacific Ocean, the changes they cause in the sea can also impact the atmosphere on a wider scale.
With La Niña, for example, greater precipitation and winds may lead to rain storms or even more hurricanes.
The Australian Bureau of Meteorology (BoM) says the sea surface has been cooling in the tropical Pacific since December 2023, with what it calls the El Niño-Southern Oscillation (ENSO) — describing the switch between the two phases — to remain neutral until at least July, indicating El Niño is over.
“The change to ENSO neutral conditions means neither El Niño nor La Niña are active,” the BOM said Tuesday.
Environment Canada climatologist David Phillips says it may not completely be a done deal, however.
“It’s on its way out, but there’s a lag,” he said.
Phillips told Global News what can happen is the oceans warm up but then the atmosphere doesn’t respond. A number of factors need to be in play, including a shift in wind direction and change of temperature in the deep water.
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But even with El Niño potentially over, Canada may not see wide-scale weather impacts during a lull between the two phases.
Moore said impacts of either event typically are seen during the winter, noting the widespread warmer temperatures and less snow this past season. Instead, Canadians will more likely see “local” weather events such as thunderstorms.
“I don’t think it will be anomalously different than usual just because it’s this phase where what happens with the El Niño or La Niña doesn’t really have an impact,” he said.
In Western Canada, however, he expects the lingering dry conditions and possible lack of snowpack will likely fuel wildfires.
“We’ll see the effect of El Niño persist into the summer, even though it’s actually gone away and that’s just because the dry conditions are probably going to lead to more wildfires in the West,” he said.
The past several months have seen record-breaking temperatures in Canada due to a mix of increasing greenhouse gas concentration in the atmosphere and El Niño, which can expand the area of warm water and add to the slow warming our climate is seeing, he added.
The country could see a return to slightly cooler temperatures in the next year, however, as La Niña is likely ushered in.
Phillips cautions, however, that it’s still only a forecast that La Niña will take place so it’s yet to be seen exactly what will happen.
“What we’re seeing is that the temperatures are headed towards that, but it’s not as if you would bet the family farm or the fishing fleet on it, because it can also go back,” he said. “It could all of a sudden turn around and be another El Niño.”
Last week, the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center said there’s a 60 per cent chance of La Niña developing over the summer months. The chances increase in the months after, but it’s not a guarantee.
Should we see the switch occur, there is the potential for Atlantic Canadians to see some impact in the coming months as a change to La Niña could result in a potentially earlier and more severe hurricane season.
La Niña reduces wind shear that typically suppresses hurricanes, and could combine with warmer sea-surface temperatures for a potentially more active season.
Canada won’t really know the effects of La Niña’s cold, however, until the winter.
Global meteorologist Ross Hull said earlier this year that while it can be difficult to know the effects for sure, he expects chillier than normal temperatures in the Prairies.
Moore said Tuesday he anticipates a colder and wetter winter in B.C. and Eastern Canada as well, though it’s yet to be seen if it’ll be rain or snow nor how long the La Niña event will last.
— with files from Global News’ Naomi Barghiel and Reuters
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