Bundle up, the polar vortex returns - but is it climate change?

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Anne/Flickr

Tomorrow, July 16, Dodge City, Kansas, is forecast by the National Weather Service to be in the mid-60s, about 25 degrees Fahrenheit cooler than average.

I promise that Dorothy and Toto are still in Kansas and that no witch is involved. It’s just the Polar Vortex of the North paying them a visit.

The last time the polar vortex hit the United States, back in January 2014, it coined a new catch phrase and caused near-hysteria as temperatures plummeted to unprecedented levels well below freezing.

In a world where our climate is changing rapidly due to human emissions of heat-trapping gases, it’s not unreasonable to wonder if climate change has anything to do with extreme weather events such as these polar vortex episodes.

Weather a complex story

It’s no different than when a patient is diagnosed with lung cancer and everyone, including doctors, wonder if it’s because she smoked, even if it’s possible that she didn’t. The same applies to extreme weather and climate change.

So it’s not surprising that there were more than 78 million hits for “polar vortex” + “global warming” in a January Google search after the wintertime polar vortex episode.

But those Google results hardly provide clarity, especially when outspoken public figureheads argue that cold spells prove that climate change is a hoax

Even now, social media is flooded with meteorologists who are lashing back at the use of the term polar vortex, further confusing a non-expert.

So is there a connection between the polar vortex episodes and climate change?

These polar-vortex-in-the-mid-latitude situations are often the result of a long chain of causes and effects. Any piece of this chain can be triggered or amplified by changing climate conditions.

The system is super complex.

When the jet stream acts weird 

The polar vortex itself is always present. It is a swirl of cold winds caused by temperature differences between the mid-latitudes and the Arctic, especially intense during winter, and trapped over the North Pole by the jet stream.

Every now and then, the jet stream gets bent out of shape, and some of the cold Arctic air penetrates into the mid-latitudes. 

Japan typhoon cooling Midwest

This past winter’s polar vortex episode was caused by a persistent high pressure system that developed over western Canada, which pushed the jet stream southward. 

The current summertime polar vortex episode is caused by the Super Typhoon Neoguri that hit Japan last week, which has dramatically altered the jet stream (and also created a high pressure system over western Canada). 

The connection to climate change

Both of these triggers—a persistent high pressure system and a strong storm —are consistent with climate change projections by experts. Even a weaker jet stream in general is anticipated as sea ice melts in the Arctic.

But just as the lung cancer patient may not have smoked, this is not evidence that there is indeed a connection between these individual events and climate change.

So why can’t you find a clear answer anywhere? Because there isn’t one.

All weather events are multi-causal and a combination of favorable conditions. Quantifying the contribution from climate change alone is therefore extremely difficult.

That doesn’t mean that a connection isn’t there, and it certainly doesn’t mean that unusually cold air during winter or summer disproves climate change.

Connection or no connection, there has been more than enough observed consequences of climate change warning us that there is a problem that we need to fix.

Because as Dorothy in The Wizard of Oz told us way back when, “there’s no place like home.”

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Ilissa Ocko

Ilissa Ocko

Ilissa Ocko is a High-Meadows Post-Doctoral Science Fellow at EDF.

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