Maybe Those Winter Storms Were NOT Caused By Jet Stream Made Weird By Climate Change

There's new debate over the specific mechanisms causing
intense winter snaps in places like the U.S. and
Europe despite an overall warming climate.

A theory about sharp winter storms and cold waves made paradoxically worse by a warming climate just took a big blow. 

I've mentioned this idea several times before during rough winter weather in the past, but here's a recap:

The theory is that the Arctic is warming faster than the mid-latitudes. That reduces the contrast in temperature between the far North and places down here. 

The reduced temperature contrast slows the jet stream, making it more prone to having bigger twists and turns along its path.  Occasional bigger southward dips in this jet stream regime would create a few intense cold snaps and winter storms, despite an overall warming climate. 

This idea gets floated a lot, like during the big Texas freeze and winter storm back in February. And it really does make sense. 

Except that new research suggests this whole wavy jet stream scenario isn't happening after all. Or at least isn't happening as much as some first though. 

The journal Science published an article recently about this new research.

As Science states:

"Now, the most comprehensive modeling investigation into this link has delivered the heaviest blow yet: Even after the massive sea ice loss expected by midcentury, the polar jet stream will only weaken by tiny amounts - at most only 10% of the natural swings. And in today's world, the influence of ice loss on winter weather is negligible, says James Screen, a climate scientist at the University of Exeter and the co-leader of the investigation."

The thought that a fast warming Arctic would screw around with the jet stream gained notice in 2012 through a paper by scientists Jennifer Francis and Stephen Vavrus that examined this idea.

Francis and Vavrus had detected a weakening of the jet stream between the 1980s and the early 2010s that bolstered their theory of a more lame, meandering jet stream causing occasional extreme winter events in North America and Europe.

That weakening trend has since petered out even as carbon emissions and climate change continued unabated.

Of course, as Science notes, something else might be going on in the overall warmer atmosphere that is causing those occasional, intense, record breaking winter cold snaps that are interrupting our warmer winters now and then. 

Is less sea ice, combined with a trend for more snow over recent decades in Siberia, causing stratospheric disruptions. Those stratospheric disruptions mess with the polar vortex.  The polar vortex - a giant whirl of cold normally in the Arctic - then gets blown to pieces temporarily, helping send frigid air from the North Pole to places like Texas or Great Britain. 

Or, maybe atmospheric rivers - channels of warm, wet air - heading toward the Arctic more frequently, somehow displacing the normal icy air up there and sending it southward to torture the snow birds in normally temperate climates?

All this uncertainty proves the following: The basic science of climate change is settled science. Anyone who still believes the climate is not changing because of carbon emissions is either a crackpot or lying. 

However, the detailed mechanisms of this warming - how it affects specific weather events, specific locations and specific aspects of our complicated atmosphere - still need lots of study.

It's important to do so, because the more understanding we have of the deep details of climate change, the better society will be at anticipating and reacting to the negative effects of what we're doing to the atmosphere.