Does global warming cause colder winters?

Counter-intuitively, yes — in some regions. A warming Arctic destabilizes the stratospheric polar vortex, the band of fast winds that normally locks cold air over the pole. When the vortex weakens or splits, that cold air spills southward and produces unusually harsh winters in places like the eastern US, the UK, parts of Europe and East Asia, even as global average temperatures keep rising.

What is a Sudden Stratospheric Warming (SSW)?

A Sudden Stratospheric Warming is a dramatic, fast warming of the stratosphere over a pole — temperatures can shoot up by 50-80 °C in a few days. It happens when upward-propagating atmospheric waves disrupt the polar vortex. The vortex weakens, sometimes splits, and lets Arctic air pour down into mid-latitudes, often triggering severe cold snaps weeks later.

Why are summers getting hotter while winters get colder?

On average winters are getting milder too, but the variability is rising. Climate change is unevenly warming the planet — the Arctic is warming roughly four times faster than the global average, which weakens the temperature gradient that holds the polar vortex together. The result is hotter summers and more frequent, more extreme winter cold-air outbreaks in mid-latitudes.

Is the polar vortex new?

No. The polar vortex has always existed — it's a permanent feature of Earth's polar atmosphere. What's new is how often it weakens or splits and pushes cold air south. Sudden Stratospheric Warming events have become more disruptive in recent decades, and most climate research links the increase to Arctic amplification driven by human-caused warming.

Why Are Winters Colder With Increasing Global Warming?

Q: What is the polar vortex?

The polar vortex is a vast band of low-pressure, fast-moving cold air that spins counter-clockwise high up in the stratosphere over each of Earth's poles. In a typical Northern Hemisphere winter the Arctic vortex tightens up and acts as a wall, keeping the coldest air bottled up over the pole. Speeds can exceed 160 km/h (100 mph).

Table of Contents (click to expand)

What Is The Polar Vortex?
Polar Vortex Affecting Weather Outside The Poles
How Global Warming Affects The Polar Vortex
Conclusion

Yes — counter-intuitively, global warming can drive harsher, snowier winters in some regions. A warming Arctic destabilises the stratospheric polar vortex, the high-altitude ring of fast winds that normally pens cold air over the pole. When the vortex weakens or splits in a Sudden Stratospheric Warming event, that trapped Arctic air spills southward and dumps brutal cold and snow on the eastern US, Europe and East Asia, even as the planet as a whole gets warmer.

Whenever we experience the strong heat of summer, we think—surely it can’t get any hotter than this! However, the very next year, it is inevitably even hotter. The strangest thing to wrap our heads around is the apparent paradox of colder winters.

Technically, the temperature of the Earth is increasing, so shouldn’t the winters also be warmer than the previous ones we have experienced?

Surprisingly, we have also seen harsher winters with our hotter summers! In fact, places where it never snows have been regularly receiving snowfall…

What is this sorcery?! As always, science has an answer for everything, or at least the tools to find all the answers. In our case, the answers can be found in the Polar Vortex.

Recommended Video for you:

Do People Live in The North Pole?

What Is The Polar Vortex?

If you recall from recent years, whenever there is the threat of unusually cold temperatures in a region, social media erupts with ‘The Polar Vortex is coming!’

This makes it sound like the polar vortex is some monster or alien invasion, and it certainly isn’t something that comes to us!

polar vortex illustration globe wind direction — The Polar Vortex contains and maintains the temperature of the Arctic and Antarctic regions. The jet stream flowing below the vortex affects the weather and are simultaneously affected by the vortex. (Photo Credit : -Bakhtiar Zein/Shutterstock)

So, what is the vortex exactly? Well, technically, there are two of these vortices, one at each of the poles. These vortices are very high-speed winds situated high in the atmosphere. To be more exact, their speeds can exceed 161 km/hr (100 miles/hr)! The reason they are called vortices is that they move in a counter-clockwise motion to form a vortex above the poles. Effectively, they form a barrier against the cold of the polar regions.

These polar vortices lie in the stratosphere, so they shouldn’t affect the weather, but they do affect the high-velocity winds just below them, which are responsible for the weather. Indirectly, they are affecting the weather. Usually, they stick to affecting the weather at the poles, but sometimes their influence can spread…

Polar Vortex Affecting Weather Outside The Poles

In our case, we are interested in the Northern Polar Vortex (the Arctic vortex), which has been responsible for our recent bout of severe winters. As stated, the vortex traps the cold of the Arctic within that region. It can be imagined as a prison for the cold. If it’s strong, the weather influencing the jet stream only brings about regular rain. However, if it weakens, the prison is broken and all the cold escapes outward.

This cold air freezes the moisture in the air, and the weather-influencing jet stream brings snow storms as a result. This is how the temperature drops so low in those polar vortex years. It’s also why regions that normally only experience mild cold with occasional rain suddenly find themselves buried under snow!

Now, the natural question is… what affects this polar vortex? If you guessed global warming, you’re correct. Let’s find out how!

How Global Warming Affects The Polar Vortex

See, global warming, as the name implies, means a global rise in temperature. This means that the atmosphere (at least the innermost layers) is warming up.

The polar vortex is a large area of low pressure and cold air surrounding both of the Earth poles — A contained and strong Polar Vortex means the cold of the Arctic is contained. However, any disruption due to the up-flowing warm air causes it to squiggle and spread the polar cold out to the surrounding regions. (Photo Credit : -Piscine26/Shutterstock)

The problem is that warm air from the mid-latitudes travels up from warmer areas to the colder Arctic region. This warm air affects the polar vortex by throwing it off balance, and the consequences are serious! In what climatologists call a Sudden Stratospheric Warming (SSW), stratospheric temperatures can shoot up by 50–80 °C in just a few days. At that point the polar vortex becomes weak or even splits into two lobes, allowing the cold of the Arctic to seep out into mid-latitude regions.

In short, the cold is no longer contained to the arctic once the vortex is disrupted. It spreads out into the surrounding regions thanks to the jet stream and, in turn, the arctic becomes less cold.

Conclusion

One surprising fact is that the effect of global warming on the Polar Vortex has been studied for a long time. There are many pieces of research that warned us these sorts of disruptive weather events were possible. This was when such bitterly cold winters were not even a recurring phenomenon.

But now, we experience a record-breaking summer of heat every year and a consequent record-breaking winter of cold as well. It has become a recurring phenomenon in recent years, and shows no sign of slacking off.

How strange that a phenomenon associated with increasing temperatures is also responsible for the coldest temps as well!

References (click to expand)