Record cold, winter cyclone symptoms of a warming planet

It was so cold, even the penguins had to be moved indoors.

The Calgary Zoo was just one of hundreds of locations across North America impacted by the recent spell of record-breaking cold temperatures. And while Canadians are no stranger to extreme cold, the seemingly never-ending blast of icy Arctic air that 2017 left in its wake has pushed many cities to the breaking point, from frozen pipes, toppled trees, dead car batteries and cracked foundations.

Urban infrastructure isn’t the only thing crumbling in the cold. People across the country are rightfully asking “where is this promised global warming?”

These un-naturally cold events are part of the ongoing lesson that climate change isn’t a synonym for global warming. Global warming is the term used to describe the relentless build-up of heat in our planet’s atmosphere and oceans caused by increasing greenhouse gas emissions, whereas climate change is the consequence of this extra heat – consequences that can include the occasional volley of unusual cold. Rest assured, Earth is still warming at break-neck speed – as evidence, consider that right now pretty much everywhere but central and southern North America is actually warmer than normal, including the Arctic!

So what’s the link between global warming and extreme cold events like this one? The details are still being worked out, but climate scientists are zeroing in on the link between warmer Arctic temperatures and the flow of the circumpolar jet stream, often called the polar vortex. Like an invisible dam, a healthy polar vortex helps keep Arctic air from spreading southward. But as the Arctic continues to warm much faster than the rest of the globe, the thermal gradient between Arctic and sub-Arctic air is lessened and as a consequence the polar vortex becomes weaker. It is during these moments of weakness that the polar vortex seems to break-away from its normal hiding place and drag Arctic air into the normally much more mild climates of southern Canada and the United States.

Like all weather events, this cold snap will come to an end. Life will return to normal. The penguins will once again be on display at the Calgary Zoo. But what is considered normal these days? After two decades in a row of warmer than average temperatures, the odds are that 2018 in Canada will be anything but.

Ryan Smith


Prairie Climate Centre

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