Sudden stratospheric warmings raise odds of extreme power demand in northern and central Europe up to threefold

A multiplier of 1.5 to 3 ^[3] is a relative risk. A grid planner needs the base rate before it says anything about how many hard days to expect. Tripling an event that happens once a winter is a far bigger operational problem than tripling one that happens once a decade. The thing the published summary doesn't tell you is how often a day 20% above average demand ^[4] turns up in an ordinary winter, or what share of the warmings studied actually brought cold to the surface ^[3].

In winter, strong westerly winds circle high above the Arctic in the stratospheric polar vortex ^[1]. Roughly once every two years that vortex breaks down and warms, and cold surface air spills south over Europe and North America ^[2]. The new work follows the chain one step further, from temperature to load. "We analyzed the relationship between SSWs and extreme electricity demand, driven by demand for heating, and found a clear link," said Regan Mudhar, now at the University of Lausanne ^[8][13].

The lead time is what makes the result usable. Cold after a warming typically arrives a few weeks after the polar winds shift, as it did with the 2018 "Beast from the East" ^[6]. Mudhar described that case with a caveat attached. "These events don't always affect surface temperatures, but this one was followed by severe cold weather in the U.K. and much of northern Europe," Mudhar said ^[7]. I'd treat a detected warming as a reason to raise readiness, with the cold itself still to be confirmed. At about one event every two years, an operator would face roughly five warmings a decade ^[14].

How hard a cold spell hits the grid depends on how a country heats its buildings. Scandinavian countries, largely well adapted to extreme cold, saw a smaller rise in electricity use as temperatures fell ^[9]. France, with a highly electrified energy system, saw a much steeper one ^[10].

For Britain, the French case is the one to study. "The U.K. is relatively well adapted to cold weather at present due to our reliance on gas central heating. However, as we transition to net zero, a lot of the traditional gas heating must be electrified (i.e., replaced with heat pumps), and then periods of cold weather with low wind will make it increasingly challenging to keep the lights on at a low cost to consumers," said Hannah Bloomfield of Newcastle University ^[11][13]. Her concern is cold combined with low wind. Wind output is a supply question, and the paper, as its title says, is about demand ^[5].

Mudhar expects the hazard to outlast climate warming. "We are, and will continue to, experience warming driven by greenhouse gas emissions, but SSWs will very likely still happen, bringing cold weather with them," Mudhar said ^[12].