For many, especially those living in the south, the Arctic outbreak that has gripped the interior of the country over the past week is the kind of cold that only happens once in a century. Numerous record cold temperatures were set. Requirements overwhelmed the Texas power grid, cutting off millions of electricity and bursting water pipes, causing a humanitarian crisis
But with climate change generally making winters warmer and hitting heat records worldwide by 2 to 1 over the past decade, this historic cold snap may seem counterintuitive. It is not. Paradoxically, a warmer climate may even have contributed to the extreme cold.
The science of meteorology has come a long way in recent decades, so much so that meteorologists have saw this extreme winter weather coming many weeks in advance. That’s because this extreme pattern was initiated by a large and recognizable phenomenon that unfolded in the Arctic at the beginning of the year called Sudden Stratospheric Warming, or SSW.
CBS News gave a preview of the wild winter weather Article of January 7, which explains how over the course of just a few days in late December and early January, temperatures in the atmosphere high above the North Pole warmed by 100 degrees Fahrenheit – jumping from minus-110 degrees Fahrenheit to minus-10.
SSWs are a natural phenomenon that occurs every few winters and predicts extreme weather in the weeks that follow. That’s because when the Arctic heats quickly, it disrupts a spinning mass of cold air – the polar vortex – a semi-permanent weather system that is present every winter.
Normally, the jet stream winds around the vortex and acts like a lasso, trapping the cold air inside. But when it gets warm in the Arctic, the jet stream gets weaker and longer, allowing the cold air to plunge south.
This allows a wide mountain of warm air to form over the Arctic, temporarily displacing the cold vortex. The warm mountain acts as an atmospheric block, diverting the jet stream and bitter cold air south.
While this bitter cold mass of air was certainly memorable for the Upper Midwest, it was not so extraordinary to them. The 1899 record was much more widespread and more serious in the north of the US.
What made this particular situation historical was that the core of the cold air – a stretch of the polar vortex – plunged much further south than ever before: a full 4,000 miles from its usual home near the North Pole.
As a result, hundreds of daily record lows were reached in the past week, targeting the south-central Plains States. Dozens of all-time records were also set as the unprecedentedly cold cities and towns unaccustomed to and prepared for the bitter explosion. The animated loop below shows monthly records in dark blue dots and all-time record cold in black dots.
This has produced some stunning images. A frozen waterfall in the Ozarks of Arkansas.
And frozen swamps in Louisiana.
This is despite a long-term trend where winters are warming all over the US and the cold is decreasing. In Minneapolis-St. Paul, for example, rose the coldest temperature of the year by 12.1 degrees Fahrenheit from 1970 to 2020.
The recent extreme weather has not been limited to the US. When the jet stream is extreme in one region, it is often extreme around the world. In Saudi Arabia, snow-covered camels made for a rare, but not unheard of sight.
Snow also fell in Jerusalem and parts of Jordan and Syria, while at the same time record heat affected other parts of the Middle East, such as Iraq, where temperatures rose to 93 degrees in winter.
How extreme cold and extreme heat are linked
While this extreme cold combined with extreme heat may seem strange, it’s actually what meteorologists would expect from a wavy jet stream. Think of it this way: what goes up must come down. When the atmosphere forces cold air south, there must be an equal and opposite reaction that forces warm air north. When air masses are moved to places they don’t usually visit, extreme weather events and the effects they have on society follow.
A number of climate scientists think that climate change not only makes sudden warming of the stratosphere more likely, but that climate change itself could have a similar effect in the Arctic, as it also causes significant warming. Due to man-made climate change, the Arctic is warming three times as fast as the global average.
Wavy jet stream theory, in relation to climate change, was developed by Dr. Jennifer Francis at Woodwell Climate Research Center. The theory makes sense: Arctic warming decreases the gradient between warm and cold air and thus weakens the temperature contrast mechanism that drives the force of the jet stream. That results in a weaker, more wavy jet stream, which is more likely to spill its cold air south.
The theory has since been adopted by many other climate scientists, who see seemingly increasing extremes, such as this latest bitter eruption, as a sign that the theory has its merit. But a large group of other scientists have their doubts about the impact of climate change and Arctic fortification on the jet stream.
That’s partly because the atmosphere is very noisy and climate models aren’t quite able to reproduce the finer details of a complex system. So it was a challenge to find evidence to definitively prove or disprove the theory. But a lot ancient meteorologists believe that the logic, research, and qualitative evidence they have observed is sufficient to justify the case.
What all meteorologists and climate scientists can agree on is that this extreme event was triggered by a sudden stratospheric warming. That was the driving force.
For those who are tired of the cold and snow, good news: it seems that the extreme pattern has taken its course. The world is about to return to a more normal pattern. That doesn’t rule out cold air outbreaks and blizzards from the US as we head into spring, but it should allow the weather to return to some degree from normal.