For many, especially people living in the South, the Arctic outbreak that hit the heart of the country last week is the kind of cold that only happens once every century. Countless records of low temperatures have been set. Conditions overloaded The Texas power grid, cutting electricity for millions and bursting water pipes, creating a humanitarian crisis.
But with climate change generating generally warmer winters and causing heat records to outperform cold records by 2 to 1 globally in the past decade, this historic cold wave may seem counterintuitive. It is not. In fact, paradoxically, a warmer climate may have contributed to the extreme cold.
Meteorology science has come a long way in recent decades, so much so that meteorologists I saw this extreme winter coming many weeks in advance. That’s because this extreme pattern was initiated by a large and recognizable phenomenon that unfolded in the Arctic earlier this year, called Sudden Stratospheric Warming, or SSW.
CBS News predicted the wild winter this January 7 article, explaining how, over just a few days in late December and early January, temperatures in the atmosphere above the North Pole increased by 100 degrees Fahrenheit – jumping from minus 110 degrees Fahrenheit to minus-10 degrees.
SSWs are a natural occurrence that happens every two winters and portend extreme weather conditions in the following weeks. That’s because when the Arctic warms up quickly, it interrupts a swirling mass of cold air – the polar vortex – a semi-permanent meteorological system that is present each winter.
Normally, the jet stream snakes around the vortex and acts as a kind of loop, keeping the cold air trapped inside. But when it warms up in the Arctic, the jet stream weakens and stretches, allowing cold air to plunge south.
This allows a wide mountain of warm air to form over the Arctic, temporarily supplanting the cold vortex. The hot mountain acts as an atmospheric block, redirecting the jet stream and cold air to the south.
Although this mass of cold, bitter air was certainly memorable for the upper Midwest, it was not so unusual for them. The record set in 1899 was much more widespread and severe in the northern United States
What made this situation particularly historic was that the cold air core – a piece of the polar vortex – plunged much further south than ever before: 6,500 kilometers from its usual home near the North Pole.
As a result, hundreds of daily record lows were set last week, focusing on the south-central plains states. Dozens of all-time records were also set as the unprecedented cold hit cities and towns unaccustomed and unprepared for the bitter explosion. The animated loop below shows monthly records in dark blue dots and all time records in black dots.
This produced some surprising visuals. A frozen waterfall in the Ozarks of Arkansas.
And frozen swamps in Louisiana.
This is despite a long-term trend in which winters are heating up across the United States and the cold is easing. In Minneapolis-St. Paul, for example, from 1970 to 2020, the coldest temperature of the year rose 12.1 degrees Fahrenheit.
The recent extreme climate was not limited to the USA. When the jet stream is extreme in one region, it is usually extreme worldwide. In Saudi Arabia, snow-covered camels were rare, but not unheard of.
Snow also fell in Jerusalem and parts of Jordan and Syria, while at the same time record heat was affecting other parts of the Middle East like Iraq, where the temperature rose to 93 degrees in winter.
How extreme cold and extreme heat are connected
Although this extreme cold combined with extreme heat may seem strange, it is actually what meteorologists would expect from a wavy jet stream. Think of it this way: what goes up must go down. When the atmosphere forces cold air to the south, there must be an equal and opposite reaction, forcing warm air to the north. When air masses are moved to places they do not normally visit, climatic extremes and the impacts they bring to society follow.
Several climate scientists think that climate change may not only be making stratospheric warming more likely, but that climate change itself may have a similar effect in the Arctic, because it is also causing significant warming. Due to man-made climate change, the Arctic is heating up at a rate three times higher than the global average.
The wave jet theory, with respect to climate change, was initiated by Dr. Jennifer Francis at the Woodwell Climate Research Center. The theory makes logical sense: warming the Arctic reduces the gradient between hot and cold air and therefore weakens the temperature contrast mechanism that feeds the strength of the jet stream. This results in a weaker, wavier jet stream, more likely to spread its cold air to the south.
The theory has already been adopted by many other climate scientists, who see the apparent growing extremes, like this latest bitter explosion, as a sign that the theory has merit. But a considerable group of other scientists have their doubts about the impact of climate change and Arctic amplification in the jet stream.
In part, this is because the atmosphere is very noisy and climate models are not yet able to reproduce the finer details of a complex system. Thus, finding evidence to definitively prove or disprove the theory has been a challenge. But many longtime meteorologists they believe that the logic, the research and the qualitative evidence they observed are 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 tired of cold and snow, good news: it seems that the extreme pattern is running out. The globe is about to return to a more normal pattern. This does not prevent outbreaks of cold air and snowstorms in the United States as we move into spring, but it should allow the weather to return to some degree of normality.