FLINT, MICHIGAN-DECEMBER 23-A family walks through a neighborbood during a winter snow storm … [+]
As the blast of Arctic air that fueled a continent-wide storm descended upon Denver this week, temperatures dropped by 70 degrees in less than 18 hours, from a mild mid-winter day to the coldest temperatures registered in over three decades.
Winter Storm Elliott stretched from the Pacific Northwest to bring freezing rain, temperatures and snow to the entire country, sparing only a corner of the Southwest, where the sun shone as per usual.
At one point on Friday, almost three quarters of the US population was under some form of winter weather warning or advisory according to the National Weather Service. Thousands of flights have been cancelled, millions are without power, at least a dozen people have died in connection with the winter system and most people are focused on digging out or hunkering down for the holiday weekend that promises to be a memorable one.
Travelers check their flight schedules at the Pierre-Elliot Trudeau International Airport in … [+]
Unless it actually isn’t in the long run.
In covering climate over the past two decades, this is an emerging pattern I’ve noticed. Phrases like “historic,” “once-in-a-generation,” or even “hundred year event” have started to carry less weight when used to describe individual weather events.
To illustrate, about 25 years ago there was a really hot summer in the Midwest. A few people in the town where I was going to college at the time succumbed to heat stroke. There was lots of conversation about what an unusually hot year it was. Someone might have mentioned climate change in the conversation, but the assumption was that the event was an outlier, part of the natural variation and chaos of the climate system.
Now try to imagine someone remarking on what a hot year it’s been without most people responding with some comment about climate change or how every year seems hotter than the last. And statistically speaking, this analysis isn’t far off. The five hottest years on record have all come in the last decade, making natural variation a less convincing explanation for the heat, to say the least.
We can now have similar conversations about “once-in-a-generation” wildfires, once-in-a-century flooding and historic hurricanes. At some point, we have to adjust what we consider as qualifying criteria to use these terms. The truth may be, that as we rapidly transition to a new climate on planet Earth, we won’t really know what normal is until a generation or longer after we finally get runaway carbon emissions under control (or it takes control of us).
The most striking example of these superlatives failing us comes in the Atlantic hurricane seasons of the last half-decade. In the span of just a few years, Hurricanes Harvey, Maria and Florence all brought widespread flooding to Texas, Puerto Rico and the Carolinas, respectively, in events that were described as hundred-year and even thousand-year floods. These three events all came within roughly a year of each other in the same basin. That’s starting to sound a lot more like new n0rmal than outlier events.
TOPSHOT – This combo of photos made on March 19, 2018 shows (above) a man rides his bicycle through … [+]
I know it may be counter-intuitive to think of widespread deep freezes and massive winter storms as part of the chaotic climate changes wrought by global warming. We can’t say right now how much or if climate change contributed to Winter Storm Elliott. There is a scientific process to attribute the influence of climate to individual weather events, but it takes a little time.
But after watching the weather for the entire century so far, I’m willing to place a bet. This holiday storm won’t be thought of as a once-in-a-generation event for very long.
Here’s what I know that makes me confident enough to make this prediction. Climate change is so far having a disproportionate impact on the Arctic and higher-latitude portions of the globe. Studies have shown that all this unusual and rapid warming in the north affects the jet stream in new and sometimes weird ways.
This impacts weather further south in the contiguous US, leading to big Arctic blasts that seem to make the headlines at least every other year. It also contributes to a phenomenon that is being discussed more often among scientists known colloquially as “weather whiplash.”
This is just what it sounds like, weather patterns doing an abrupt 180-degree turn, like Denver going from mild and sunny to that “once-in-a-generation” cold.
It’s time to temporarily retire these superlatives and steel ourselves for a new era in which we expect the unexpected and assume that there are no outliers anymore.
Stay warm and safe wherever you are this holiday season.
