In the media: Chris Fletcher explains why higher temperatures increase the intensity of storms

Monday, April 24, 2017

water institute members in the mediaTVO recently featured a story on the massive flooding in Windsor last year, and how catastrophic events like this are a sign of climate change. The science behind these ever-intensifying storms is more complex than it seems. TVO interviewed experts on climate change to help explain the science behind these events. 

The story includes comments by Water Institute member Chris Fletcher, of Geography and Environmental Management and the Interdisciplinary Centre on Climate Change.

"How climate change is making storms more intense"

By Tim Alamenciak, Apr. 21, 2017

[...] Last fall, a massive storm hammered Windsor, inundating streets and houses across the city. The record rainfall flooded more than 1,700 homes, with damages estimated at $108 million. The storm had gotten stuck in a stalled-out current, whirling above the city for two days as it dumped water on a small area.

The event was characteristic of a changing climate. Normally high-altitude currents  — which form when hot air from the equator clashes with cold air from the poles — would have blown the storm away. But high above Windsor, a slow spot in the jet stream allowed the rainclouds to linger.

More of the same is in our future: with the Arctic heating up, the temperature difference between equatorial air and polar air is getting smaller — and it’s doing weird things to the jet stream.

That may seem like a too-vague term to use, but the fact is, scientific research into jet stream changes is being thrown for a loop by the rapid pace of global warming. It’s still not clear how drastic changes to the jet stream will be.

“We like to focus on things that are high-impact and affect our lives, but it tends to be something of a paradox that those things are less understood,” says Chris Fletcher, an assistant professor of geography and environmental management at the University of Waterloo.

Rain and snow storms fit into two broad categories, and climate change is affecting both profoundly. Thunderstorms, which occur in warmer months and stay close to the ground, generally dump water from the local area that’s been drawn into the air via the hydrologic cycle. Conversely, cyclonic storms — the kind that hit Windsor last year — float higher in the sky and travel hundreds of kilometres. Those that pass through Ontario are, for the most part, carried by the jet stream.

“The physics involved in those two types of storms are quite different,” Fletcher explains. “Climate change, this wild card that's coming on-stream, may affect those two types of storms differently.”

[...]

Read the full story by Tim Alamenciak in TVO

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