This Christmas was one for the books. While I was lucky enough to spend it in Colorado with my family, snowboarding and enjoying the fresh snow, the cold temperatures were hard to ignore, especially from Wednesday to Friday. The entire United States experienced a polar vortex unlike any we've seen before. This winter storm brought massive amounts of snow and temperature drops from California to Florida. The National Weather Service even called it a "once-in-a-generation event". Over 90 million people were under winter weather alerts and over 87 million under wind chill alerts, covering 37 states as far south as the Texas-Mexico border (Beals).
So what does this have to do with global warming?
It may seem counter-intuitive, but there are some reasons that may be linking this extreme weather to global warming. As the Earth warms up, water vapor is trapped longer in our weather cycles, leading to heavier snowfall and colder temperatures in the winter (Beals). Another factor is the warming Arctic and the changing jet stream patterns during the seasons. This phenomenon is known as global "weirding". Climate change doesn't just mean global warming; it also includes extreme cold weather events.
To understand this better, we need to look at how jet streams behave in the summer and winter. The jet stream is like a river of air that carries storms and weather events around the world. The polar jet stream separates the cold Arctic air from the more moderate climates.
In the summer, the Northern Hemisphere faces the sun, bringing warm, moderate temperatures to the United States. "Since there is more warm air (or less cold air) closer to the North Pole, the jet stream migrates northward. It also moves in a west-to-east direction, called zonal flow" (Furer). This results in a slow-moving jet stream that often brings prolonged heatwaves to the United States.
In the winter, cold temperatures build up in polar regions and the jet stream behaves differently. "It migrates southward and moves in a north-to-south or south-to-north direction, called meridional flow. When it moves north to south, it carries the cold air south. When it moves south to north, it carries the warm air poleward" (Furer).
Traditionally, this is how jet streams have behaved, but global warming is changing this. Winter temperatures in polar regions are rising, causing the jet stream to destabilize. When it wobbles, it can sway further southward or northward. When it swings southward, as it did during the recent polar vortex, it brings cold temperatures further south to states like Texas and Florida. These cold temperatures, caused by a slowed jet stream due to warm weather, can last for a few days. This is unusual for destabilized jet streams and is exactly what we saw in the recent winter episode.
It isn’t weird that these cold weather events are happening, the alarming aspect is seeing these events push further away from historical data. As the temperatures continue to change, these events will become more and more unusual… long summer heat waves and bitter winter weather in states that haven’t ever experienced such events. Beyond just the short term repercussions of these weird weather events, the long term repercussions are what we must be most concerned about. These patterns are continuing to change, and recorded temperature rises in polar regions year after year foreshadow a scary future. We must realize these changes are a result of of our actions, and begin doing our part to voice our concerns, learn, and combat. This isn’t just about our generation, but the longevity of humanity. Weird weather episodes have occurred long before humans existed, but the trends occurring now aren’t just something we can write off as unrelated to humanity.
Beals, Rachel Koning. “Climate Change and the Polar Vortex: Winter Storms Are Normal, but This String of Severe Christmas Weather Isn't Typical.” Morningstar, Inc., Dow Jones, 24 Dec. 2022, https://www.morningstar.com/news/marketwatch/20221224292/climate-change-and-the-polar-vortex-winter-storms-are-normal-but-this-string-of-severe-christmas-weather-isnt-typical.Furer, Ferdinand. “Climate Change Is Leading to Global ‘Weirding," Not Just Global Warming.” Climate Change Is Leading to Global "Weirding", 28 Feb. 2021, https://spectrumnews1.com/ca/la-west/weather/2021/02/27/climate-change--not-just-global-warming--but-global--weirding-.