The term “polar vortex” has become part of the common vernacular as of late.

A system previously unknown to most people, the polar vortex is a large area of low pressure and cold air surrounding the Earth’s North and South poles. The term vortex refers to the counter-clockwise flow of air that helps keep the colder air close to the poles (see left globe in graphic). Often during winter in the Northern Hemisphere, the polar vortex can become less stable and expand, sending cold Arctic air southward over the United States with the jet stream (right globe), reports the National Oceanic and Atmospheric Admin (NOAA).

When the polar vortex is at its strongest, it’s also well-organized – that is, a kind of hurricane-like structure that circles tightly just where its name suggests, at the pole. It’s only as the system weakens that it stumbles. A disrupted vortex can stumble, wobble, and split or shift far from the pole.

Emerging research suggests that a warming Arctic is causing changes in the jet stream and pushing polar air down to latitudes that are unaccustomed to them and often unprepared. Hence this week’s atypical chill over large swaths of the Northeast and Midwest, according to The New York Times. Temperatures in the upper Midwest were forecast to be in the 40 below zero range, making it colder in Chicago than at the North Pole. In West Virginia, Governor Jim Justice issued a forecast warning of wind chills to fall below zero for most locations in the state by midweek and actual temperatures would fall below zero for most locations by Thursday morning.

The extremely low temperatures this week in parts of the United States stand in sharp contrast to the trend toward warmer winters. They may be a result of warming, strangely enough. Global warming is bringing up the average temperature of the planet. Like a wrench in the system, climate change is bringing “jagged, extreme disruptions that can be measured by extremes – even extreme cold.” (dailykos.com/stories/2019/1/30/1830853/-Anthropocene-The-Age-of-Extreme-Weather)

Extreme heat, though, is the bigger problem overall.

As a polar vortex hits the U.S. Midwest, the extreme opposite is happening in Australia. The heat wave has parched landscapes, triggered damaging wildfires, pushed demand on the power grid to the brink and toppled significant records, per a Washington Post article. The continuing heatwave in Australia is a genuine ecological disaster, threatening the continued existence of species already under stress, and bringing fires to a blistering, dry landscape.

Temperatures soared to 116 degrees on Thursday in Adelaide, South Australia. That’s the highest temperature for any capital in Australia. In the southeastern corner of the country, overnight temperatures were as high as 96 degrees – the warmest overnight lows for January anywhere in the world.

Whether it’s a cold snap, a wildfire, or a hurricane, as the consistent weakening of the conditions around the North Pole continue, there’s a high probability that unpredictable extremes are likely here to stay.