British Columbia

Climate change could mean more big snow storms, scientists say

Although it might seem counterintuitive, climate scientists say that as global temperatures continue their upward trend, we can actually expect to see more intense snowfall events, not less.

It may seem counterintuitive, but increasing global temperatures mean more precipitation — including snow

Communities across B.C., such as Nelson, have seen record-breaking snow fall this month — and climate scientists say a warming planet means we can expect more big snow events in the future. (Bob Keating/CBC)

B.C.'s South Coast has spent the last week in the icy clutches of winter, wrapped in the fifth major snow and cold weather storm of a season that normally only sees one or two.

But although it might seem counterintuitive, climate scientists say that, as global temperatures continue their upward trend, we can actually expect to see more intense snowfall.

"Quite often people will think that, wow, look at this huge snow storm, what happened to global warming?" said Mel Reasoner, a climate scientist with the Columbia Basin Trust.

But warmer air can hold more moisture, Reasoner says, which means that increasing temperatures tend to result in an increase in precipitation year-round, including snow.

B.C. records broken

In a 2012 paper, Kevin Trenberth — a climate scientist at the National Center for Atmospheric Research in Colorado — found that, as average temperatures increase, we should expect to see record levels of precipitation more often.

It's certainly been a record-breaking start to the month of February in B.C.

Armel Castellan, a warning preparedness meteorologist with Environment and Climate Change Canada, says the most recent storm has set records across the province.

"Those are pretty impressive in and of themselves, because some of them are not just daily records for that day in the year, but daily records all-time for a whole month, or even a whole winter," Castellan said.

Abbotsford saw 69.0 centimetres of snow fall in the first nine days of the month, which puts it on track to tie the all-time monthly record.

But another important record is being broken too. Castellan says 2016 was the warmest year on record, globally speaking, and at least the fifth or sixth warmest year for every B.C. location that Environment Canada tracks.

For Reasoner, these records being broken concurrently is no coincidence. In fact, it's exactly what Trenberth's work predicts — and the warming trend is expected to continue.

Though temperatures vary from year to year, the average temperature in the months of December, January and February has been trending upward for the last 100 years. (Mel Reasoner)
Despite a slight downward trend in average winter snowfall totals in Vancouver in the last 100 years as average temperatures have increased, there is a great deal of variance and extreme snowfall events are still a very real possibility. (Mel Reasoner)

Arctic complications

But hold on, residents of the Lower Mainland might be tempted to think — what about the five extended cold snaps this winter, in a region Castellan says typically only sees one or two?

In B.C., such cold snaps are typically caused by intrusions of cold Arctic air from the north — and Reasoner says there's an increasing body of research suggesting that retreating Arctic sea ice may cause this to happen more often.

"Some of that really cold air in the Arctic has been able to escape, if you like, from the Arctic more easily and push further south into British Columbia," Reasoner said.

The results can be dramatic when that cold Arctic air meets warm Pacific air.

"You create sort of the perfect storm for increased precipitation, and if it happens to be just below freezing, then you're going to end up with huge amounts of snow," he said.

Snow piled up in downtown Vancouver during the city's record-setting cold snap of 1916. (Vancouver, B.C., Engineering Services)

Variability distracts from trends

For Trenberth, all weather events are influenced by climate change, because they're happening in environments that are growing increasingly warmer and wetter.

Reasoner says it can be hard to square all of this local weather variability with the idea that temperatures are, on average, increasing.

But according to data collected by thousands of scientists around the world, it's undeniable: the planet is getting warmer.

"The climate system is a very variable thing, and I think it's in our DNA to focus on these extremes," Reasoner says. "But the really important thing is to keep your eye on the trend."

With files from Greg Rasmussen