If you are living in the United States right now, chances are you have noticed that it is a bit chillier than usual. Maybe you even have some lovely snow on the ground to add to this blissful chill.
This cold weather has been quite popular on the radio, especially since the news casters get to use the words “polar vortex.” It has the word polar in it so it sounds really cold. Sometimes it is referred to as “this phenomenon called a polar vortex,” and sometimes it is “a polar vortex is bringing cold air down south.” What you really should know though, is that the polar vortex is the winter time jet stream.
Ultimately though, my favorite part about these little cold snaps is the responses that people have to them. There always has to be that person that comes along with a jolly laugh and says, “Where’s that global warming now?” Some of the arguments by pundits are fascinating (in a terrifying way) but when you start to read the Q and A on popular news sites like CNN, you can actually start to understand how easy it can be to take advantage of those who grew up with an American science education. Questions like this were actually used on the CNN website:
Sigh, and this is what happens when people on the news talk to viewers like they are 5 year olds.
What should they be telling us? Well, they could at least take a stab at explaining it more scientifically.
Climate change and colder weather
Why would a changing climate cause colder winters?
Well, this fascinating thing called the polar vortex (or winter jet stream) generally moves wind zonally around the world (which means in the west to east direction). At certain points this vortex weakens and can become more disrupted by large scale waves, or even break apart entirely, which is what happens in a sudden stratospheric warming event. During these breakdown events, cold air is displaced to lower latitudes.
Events where the vortex splits or breaks down for a few days are normal and have been recorded throughout history. The issue is that these events are becoming stronger and more common. There is a reason for this.
As described in this article (that includes a great video link and a plot), the zonal winds associated with the jet stream have decreased in more recent years, and this correlates with decreases in arctic sea ice.
So, when the jet stream is weakened, more breakdown events will occur. This means more cold snaps. We see this happening right now.