How do warmer average global temps cause colder winters?


Like the title says, I know that global warming does produce colder winters but I’m unable to explain how.

In: 6

It creates more instability at the poles which cause more extremes in Temps. The polar vortex becomes more bean shaped when it should be more circular.

Because of this bean shape, in the northern hemisphere, we warm our cooler polar air all at once in the spring instead of it keeping our summers mild. This cycles gets progressively worse as the ice caps melt.

More energy in the system = more events/instability

In North America that instability was recently reflected in air currents from the polar regions extending/being pushed way outside their “usual” zone and down across most of North America, resulting in some very cold weather for a couple weeks.

Note that a handful of very cold “events” in any given winter don’t necessarily mean the winters as a whole are getting colder. Follow USDA cold hardiness zones and first/last frost dates and the trend over time is that first frosts are happening later, last frosts are happening earlier and overall winters are getting warmer, just with more severe weather.

They cause more variance in temps as weather patterns destabilize.

Take for example, the Polar Vortexes we hear about from time to time that bring super cold temps. Normally, there is a tightly spinning vortex of cold air over the North Pole. Looks like a tightly formed hurricane, but instead of a tropical storm it’s extremely cold. Now, weaken that air mass with warmer temperatures globally, and the tight spiral weakens, loosens, unravels and whisps of it dip further down beyond the arctic circle and bring that super cold air down with them. Not as intense as it was, but spreads further out.

It doesn’t – not on the whole anyway. On average winters on planet Earth are getting warmer. That’s what the global climate is doing.

However, even as winters on average across the globe are getting warmer, it is possible that some winters in some places, or even the average winter in a given place, are getting colder. See, weather, and weather patterns, are complicated. How warm or how cold it is in a given place is strongly influenced by currents in the ocean and in the atmosphere. If you get a lot of air blowing in from the North Pole, that air brings cold with it. Whereas, if you’re getting a lot of air blowing in from tropical regions, that air will be warmer.

Global warming can change the way that air and sea currents across the globe tend to flow. For instance, one possibility that has been speculated about is that the Gulf stream could be affected. This is an ocean current that, amongst other things, carries warm water from the Gulf of Mexico towards northwestern Europe, which is why countries there (like France, Ireland, the UK, the Netherlands, etc.) have warmer climates (and especially milder winters) than you’d “expect” from their latitude. For instance, Amsterdam is at about the same latitude as Calgary, Canada, but while the latter sees average temperatures of -7°C in January, Amsterdam averages above 3°C. If, as a result of global warming, the Gulf Stream no longer reached northwestern Europe, winters here would get a lot colder.

These kinds of effects are why the term “global warming” has been largely replaced by the term “climate change”, to emphasize that even though global average temperatures are rising, local effects can be more complicated than that.

The recent extreme cold in the US was caused by air blowing in from the North Pole, in a phenomenon called a “polar vortex”. It is possible that climate change will make such polar vortices happen more often. However, even in the US, winters on average have been [getting warmer](