“Irreducibly unpredictable”
The climate is such a vast and complex system that it generates a lot of ‘noise’, making it hard to distinguish patterns and trends. By developing more precise models for Canada1Water, Senior Climate Scientist Andre Erler and his colleagues hope to bring newfound clarity to Canada’s climate picture — and solve some enduring puzzles.
Andre Erler is a Senior Climate Scientist at Aquanty and climate lead on the Canada1Water project, coordinating all activities related to climate, snow and permafrost.
Many climate patterns are perfectly obvious. The annual changing of the seasons is regular enough that it’s often hard to rent a cottage even six months out from July, and mechanics’ bays predictably jam up with snow tire appointments in late fall.
But other cycles can have much longer periods — 10 years, 15 years, 50 years or more.
“We often don’t have enough data to identify those longer-term patterns,” says Erler. “Teasing out a 50-year period is hard if your recorded observations only go back 100 years.”
Beyond the sheer scale of time involved, many climate-related phenomena are also variable or irregular. El Niño, for instance, sometimes occurs once every couple of years but can be as far apart as every seven years or more. And the Pacific Decadal Oscillation (PDO), which affects Pacific Ocean temperatures and has a marked impact on weather in the Canadian Prairies, seems to have a period of roughly 15 years, though it may also have a secondary period of 50 years.
Adding that kind of variability to a climate that’s already uncertain can make it tough to develop reliable long-term models. Yet reliable models are exactly what many people are eager to have — particularly in regions like the Canadian Prairies.
Are the Prairies getting drier?
Recent dry spells have some worrying the Prairies are undergoing irreversible climate change, and certain models suggest Prairie summers will get progressively drier throughout this century. But are they right? Given the Prairies’ crucial role in Canadian agriculture and food security, the answer matters.
“Many global climate models have the Prairies generally too dry in summer and too wet in winter,” says Erler. “Those generalizations underestimate the true variability of the seasonal cycle. The Prairies actually tend to get most of their precipitation in summer for a number of reasons, including the region’s placement in the Rocky Mountain rainshadow.”
By giving a better representation of Prairie climate resolution — including the mountains, land-surface interactions, and hydrological impacts on the atmosphere — Canada1Water will help clarify the region’s climate patterns and provide a more accurate climate outlook to the end of the century.
A matter of probabilities
Over time, it’s conceivable that climate change will have an impact on climate variability, though exactly how is unclear.
“Precipitation extremes may become more intense but shorter — in other words, more variable — while temperatures may become less variable due to the controlling effects of humidity,” says Erler. “But there’s really no way to say for sure at this point.”
While Canada1Water will model long-term trends and patterns to the end of the century, climate variability and unpredictability mean it won’t predict specific events like a flash flood on a given day in the year 2080.
“We can only study likelihoods in simulations because climate is fundamentally random,” Erler says. “It’s why you can only predict the weather a couple of weeks out. Even quantum perturbations affect the macro system — what’s called the Butterfly Effect. It’s irreducibly unpredictable on a certain scale.”
“Many global climate models have the Prairies generally too dry in summer and too wet in winter. Those generalizations underestimate the true variability of the seasonal cycle.”