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Our climate has been constantly changing with a trend towards warmer average temperatures, especially in recent decades.
But within this steady rise, of course, we have variations.
One of the biggest predictable changes in the climate of an area has to do with El Niño and La Niña. In Spanish, the words mean boy and girl; in time, they are climate patterns in the Pacific Ocean that can affect weather conditions around the world.
The climate works like a pendulum, oscillating from the conditions of El Niño, through the neutrals and then to the conditions of La Niña. Sometimes the pendulum is faster, sometimes slower.
But what happens when the pendulum sticks?
We could find out this winter. The projections point to the possibility of a “triple descent” – that is, the third in a row – in the winter of La Niña.
We are in a situation of La Niña right now and we have been in La Niña winters since 2020.
According to the latest World Meteorological Organization (WMO) report, there is a 70 percent chance that La Niña will continue during the summer and a 50 to 60 percent chance that it will continue until the end of the year. . another winter.
But what does this mean for our local climate? And what about the million-dollar question: What role does climate change play?
What is La Niña?
La Niña means that the waters of the ocean on the surface of the eastern Pacific Ocean are colder. It is the opposite of El Niño, where these water temperatures tend to be warmer.
The benchmark for declaring El Niño or La Niña is half a degree above or below a long-term average, but of course it can be more significant than that. However, this innocent change can have a major impact on the climate on the Pacific coast and globally.
La Niña has colder temperatures than usual in the Pacific Ocean, which could lead to changes in weather patterns in western Canada. (The weather network)
According to the WMO, this ocean cooling can cause changes in tropical atmospheric circulation, mainly with winds, pressure and rain.
“When there is La Niña, it is usually followed by a kind of drought in East Africa and a drought in the coastal area of the Gulf of Mexico. And floods in other parts of the world, for example, in West Africa,” he says. Wilfran. Moufouma Okia, head of the WMO Regional Climate Prediction Services Division in Geneva, Switzerland.
But these cold ocean waters also play into our Canadian climate.
During the La Niña years, lightning in North America often shifts further north, causing changes in temperatures, storm tracks, and rainfall, especially in the winter months.
“It tends to mean cooler-than-normal conditions for much of western Canada and wetter-than-normal conditions in southern BC, near the coast,” said Nathan Gillett, a researcher at Environment and Climate Change Canada.
Triple-dip La Nenes is rare
Although La Niñas vary in length and strength, if this one rolls into another winter, it would be the third La Niña triple dive since 1950, according to the WMO.
“It’s a rare phenomenon,” Gillett says.
But it’s not unheard of, Moufouma Okia adds.
“This episode of La Niña is not new in terms of duration,” he says.
The Girl’s Canadian impact
In the past, our La Niña winters have meant a wild climate for western Canada.
La Niña often means colder winters in Alberta and Saskatchewan, and humid weather on the west coast. (Christy Climenhaga / CBC)
In the winter of 2010-11, during a particularly powerful La Niña, heavy snowfall dominated western Canada, with Mount Washington Alpine Resort on Vancouver Island seeing more than 500 inches of snow at the end. December.
That La Niña also meant cold winter temperatures in the prairies and heavy snowfall in Alberta, where Edmonton saw about 160 inches of snow between October 2010 and March 2011. The capital of Alberta typically saw about 85 inches of snow. centimeters during this time period.
During a three-year La Niña event in the late 1990s, the storms brought record snowfall.
A record 145 centimeters of snow (about 4.75 feet) fell in a single day on Lake Tahtsa, located off the coast of British Columbia about 120 kilometers southeast of Terrace, according to Environment and Climate Change Canada. The storm of February 11, 1999 was right in the middle of those three years of La Niña.
Climate change and La Nena
The relationship between climate change and our conditions in La Niña is a bit complicated, says Moufouma Okia.
There is no clear link between more affected areas and climate change, he says. But by 2050, a change in precipitation is expected.
“There would be extreme rainfall in places where we normally have the impact of La Niña or El Niño,” he says.
Gillett adds that while El Niño and La Niña will continue in the future, our neutral state between the two may begin to change more warmly.
“It is expected to remain the dominant mode of variability,” he says. “The type of pillar is expected to change slightly towards conditions similar to El Niño.”
Our planet is changing. Our journalism too. This story is part of a CBC News initiative called “Our Changing Planet” to show and explain the effects of climate change. Keep up to date with the latest news on our Climate and Environment page.