by Simon Donner
The quote of vortex week comes from Weather Underground climate historian Christopher Burt:
The only significant thing about the cold wave is how long it has been since a cold wave of this force has hit for some portions of the country–18 years, to be specific. Prior to 1996, cold waves of this intensity occurred pretty much every 5-10 years. In the 19th century, they occurred every year or two (since 1835). Something that, unlike the cold wave, is a truly unprecedented is the dry spell in California and Oregon, which is causing unprecedented winter wildfires in Northern California.
This week was extremely cold across much of North America, thanks to a dip in the jet stream bringing cold Arctic air far south into the United States. Many minimum temperature records were broken.
Broken records are a normal thing in a stable climate. The dynamics of the atmosphere and oceans means that low and high surface air temperature records are broken in some locations every year.
What’s abnormal is that the climate is warming, due to human activity. The average weather is warming and record cold snaps, like this week’s, are becoming less common. Thanks to that, our psychological baseline for weather has shifted. What today seems remarkable and unprecedented was actually not that unusual in past winters. We just have short memories.