A gradual warming of the atmosphere coupled with a melting snowpack and receding glaciers is likely to lead to continued incidents of extreme weather, says a Canadian water-policy expert.

Bob Sandford, EPCOR Chair for the Canadian Partnership Initiative of the United Nations Water for Life Decade, took some of the world's leading water and climate scientists, engineers, risk managers, municipal planners and policy experts on a tour of the Columbia Icefields in the Canadian Rockies on Wednesday.

Sandford said he wanted to give the experts — who are attending an extreme weather conference in Banff, Alta. — a chance to "see first-hand why we're concerned about warming effects on the hydrological cycle."

"We're talking about how warming temperatures are affecting the depth of snow cover, the depth of snowpack, the length of time when it is there and the effect of these changes on glacier mass, which is to say how much snow is available to feed and sustain these glaciers."

'It's clear that the trend is continuing and we're now very concerned from research that has been collected that it might be accelerating.'—Bob Sandford, Canadian water-policy expert

The diminishment of the Athabasca Glacier on the icefields is pronounced, with markers dating back decades showing just how far it has receded. It appears to be getting worse.

"It's clear that the trend is continuing and we're now very concerned from research that has been collected that it might be accelerating," he said.

The experts, from the U.S., Canada, China and Japan, are in Banff, Alta., attending an extreme weather conference called Storm Warning: Water, Energy and Climate Security in a Changing World.

"If we had this conference 10 years ago we'd still be dealing with projections with a lot of anxiety about how accurate the projections were. We're no longer looking at models — we're seeing widely demonstrated examples," Sandford said.

'Dramatic changes' to snowpack

He added that for every degree the average temperature rises as a result of global warming, the atmosphere can carry seven per cent more moisture.

"You're getting rapid and quite dramatic changes to snowpack and snow cover," he explained.

"What we're seeing as a consequence of that is more extreme weather events. In 2005, for example, there was a two-hour storm in Toronto that caused $700 million worth of damage, mostly to water-related and transportation infrastructure."

The 2005 storm saw as much as 150 mm of rain fall in a two-to-three hour period, overwhelming sewers and causing a chain reaction of backups and flooding.

Sandford also blames the warmer air for heavy rain in California as well as widespread flooding in Australia and Pakistan. He said "massive water vapour rivers" are being transported through the clouds and deposited in areas where such storms are rare.

He acknowledges that figuring out how to respond to the hydrological change won't be easy. Sandford said simply reducing greenhouse emissions won't be enough to remedy the problem and it is more likely going to require what he called "ecological restoration" to slow and minimize the effects.

"It's no longer a question of what might we do in the future — we now know it's happening right before our eyes."