Europe was colder than the North Pole this week. How could that be?

Subfreezing temperatures have spread across much of Europe over the past week, stretching from Poland to Spain. Snow fell in Rome for the first time in six years. Britain issued a “red alert” warning. Norway recorded the lowest temperatures of the cold snap: minus 43 degrees Fahrenheit (minus 42 Celsius) in the southeast part of the country on Thursday.

If Europe feels like the Arctic right now, the Arctic itself is balmy by comparison. The North Pole is above the freezing mark in the dead of winter; there are no direct measurements there, but merging satellite data with other temperature data shows that temperatures soared this week to 35 degrees Fahrenheit (2 degrees Celsius). That is 50 degrees Fahrenheit above normal, and 78 degrees warmer than in parts of Norway.

The Arctic warmth and the European cold snap have raised questions over whether the unusual weather occurrences are linked to each other, and if they are somehow related to climate change. Here are some answers.

A: Probably, according to Judah Cohen, a climatologist who is director of seasonal forecasting at Atmospheric and Environmental Research, a weather risk assessment firm. Cohen is the author of a 2017 study that linked a warming Arctic to the intermittent blasts of cold that those of us in the Northern Hemisphere have come to know as the polar vortex.

The polar vortex is a low-pressure system that, as its name suggests, ordinarily rests over the North Pole. (There is also a polar vortex over the Antarctic.)

When it behaves normally, the polar vortex helps trap cold air in the Arctic.

“It’s locking in that cold air at the high latitudes in the Arctic region,” Cohen said, comparing the polar vortex to a dam holding back the frigid arctic air from the rest of the Northern Hemisphere.

But sometimes that dam bursts as the polar vortex weakens and allows cold air to escape the Arctic to more temperate climes. This has always happened from time to time, but a growing body of research suggests that, because of climate change, the warming Arctic is weakening the polar vortex.

A: Researchers are still figuring out how the warming Arctic is triggering the polar vortex’s aberrant behavior. Some of them, including Cohen, point to the melting sea ice and lack of snow cover over Siberia, caused by global warming. Cohen says the loss of ice and snow creates patterns of high pressure near the Barents Sea and Kara Sea off northern Russia. That high pressure blocks the low-pressure system of the polar vortex, weakening it in the process.

There is not yet a scientific consensus over the root cause of the weakening polar vortex; it’s fair to say that it is not as definitive as, say, the evidence for human-caused climate change, which is agreed upon by 97 percent of climate scientists.

But it’s worth noting that in January the extent of Arctic sea ice was the lowest ever recorded for the first month of the year. In some parts of the Arctic, the sea ice is already breaking up before winter’s end. And Arctic sea ice has been declining since at least the late 1970s.

A: When the polar vortex weakens, it allows cold air to escape and head south. This is what Cohen suspects happened in late December and early January when the Northeast United States endured some of its coldest temperatures on record. Other researchers who conducted a rapid analysis of the weather event aren’t so sure, though they stress theirs is just a first pass at the data.

In the days leading up to the European cold snap, the polar vortex didn’t just get weaker, Cohen said — it split into two.

One piece went into northern Eurasia and drifted westward into Europe, earning it the nickname “Beast from the East.” The other piece wound up in northwestern Canada, which led to the Western United States cooling off after an unusual warm period.

“The West, that their winter is being saved to some degree, completely has to do with this polar vortex split,” Cohen said.

But meanwhile, some countries like Spain that are wholly unused to the cold are freezing.

A: Cohen likens the Arctic to the refrigerator in your kitchen. When the refrigerator door is closed, the fridge stays cold and the kitchen stays warm, but if you leave the fridge door open all the cold air comes out. Because air is spilling out of the fridge, it has to be replaced by surrounding air — air also has to flow into the fridge, or in this case the Arctic. And since the air outside the Arctic is warmer, it will necessarily move in.