La Niña’s kept things cooler this winter. But what happens when that cooling effect vanishes?
Global News
La Niña, a weather pattern associated with cooling, is weakening. Climate experts are predicting a blast of heat this year and even more so in 2024, fueling global warming.
It’s been a snowy, blustery and bone-chilling winter for many Canadians. British Columbians were digging out of abnormal snow in early March. The Prairies have seen a good dose of good old-fashioned winter, and extreme cold warnings were issued in Ontario, Quebec and the Atlantic provinces as well. Then there was the Christmas travel period thrown into chaos by winter storms – a huge mess from coast to coast.
One thing that points to all that cold weather is La Niña. It’s a climate pattern that results in cooler ocean waters building up off the coast of Ecuador and Peru. That sets off a change to atmospheric conditions further north, resulting in cooler air over the west coast of North America, and drier air in the southern United States.
Now, that period of cooling is weakening, which could usher in a prolonged period of extreme heat – possibly even pushing average global temperatures past that all-important threshold of 1.5 C beyond which, scientists fear, the planet will cross irreversible tipping points.
La Niña is a climate phenomenon that results in cooler-than-normal waters appearing off the coast of South America, near Ecuador and Peru.
La Niña occurs when stronger trade winds push warm water away from South America and toward Australia and Indonesia across the equatorial Pacific Ocean, which leaves a buildup (or upwelling) of cold water.
That cooler air inhibits cloud formation, and rain, in the eastern Pacific near South America. It also generates a lot of rain in the western Pacific over Indonesia. Those anomalies push the jet stream – high-altitude bands of fast-flowing air that control the weather – further north. Changes in atmospheric conditions have a spillover effect on weather patterns over North America that can last for months.
La Niña is usually associated with a period of cooler temperatures, especially in Western Canada, says Bill Merryfield, a research scientist with Environment Canada’s climate modelling office. He says La Niña’s chilling effect might have tempered the wildfire season in B.C. last year.
But the impacts can be felt even months after La Niña starts to dissipate, which has already started. Because of those lingering effects, Merryfield says Environment Canada is predicting a cooler spring on the west coast of Canada. But that doesn’t mean we aren’t in store for much more heat in the not-so-distant future.