How Climate Change is causing colder periods of winter weather in some places
We’ve all heard them: during a cold snap, someone is bound to say something like, “So where’s all that global warming we’ve been hearing about? Guess it isn’t real, eh?” But for many places, when an unusual spell of really cold winter weather settles in, it may be caused by global warming. Let’s look at how and why.
Most people are aware that the Arctic has been warming about twice as fast as most other parts of the planet. And that unusual warming causes unusual disruptions and perturbations in the flow of the jet stream, which historically has followed a rather meandering path – but now that path sometimes makes more extreme detours, with more frequent extreme southerly loops that suck winter-cold arctic air down into places that have seldom experienced it in the past.
The flow of the jet stream becomes weaker, and according to a number of scientists studying the phenomenon, that can also result in weather becoming “stuck” during all seasons: longer heat waves and droughts, longer periods of intense rainfall, longer cold spells and so on.
Some of the heavier rainfall and bigger snowfalls are easy to connect with global warming: as the average temperature of the atmosphere rises, the warmer air can absorb and hold more moisture – and let it go again, as rain or snow. We hear about “atmospheric rivers” which are flows of moisture-laden air that release it in prolonged and heavy rain events. Or snowfalls.
Global warming is now called "climate change," at least partly because the results are so much more complex and far-reaching than mere warming, and because the effects are so variable from place to place and from time to time. Yes, all those effects are caused by increasing average temperatures globally, but sometimes the average is reached by greater extremes. These years, the planet is experiencing more extremes of heat than of cold, but during a cold snap that fact may not be evident to the person whose car won't start because it's colder than it's been for the past few decades in that neighbourhood.
Environment Canada recently issued a cold-weather warning for much of Canada. Has global warming contributed to our cold snaps? Probably. For more detailed reading on the topic, see a few links supplied below.