Thread by @ryankatzrosene

A blast of extreme cold air has plunged deep into central North America. Some places have set record cold temperatures. It turns out there’s a bit of a scientific debate about whether these types of cold snaps can be linked to… *global warming*

🧵on what the science says…

The general idea is that melting sea ice within the warming Arctic is causing instability in the jet stream, resulting in large Rossby waves which during the winter season can push frigid Arctic air deep into areas where they wouldn’t in a more stable climate…

https://twitter.com/historian_steve/status/1745920780624711886

The idea really gained traction after this 2012 paper came out, titled “Evidence linking Arctic amplification to extreme weather in mid-latitudes”: agupubs.onlinelibrary.wiley.com/doi/full/10.10…

By the late 2010s this became a common theory - that there was an association between Arctic warming and extreme weather events in sub-Arctic latitudes. A great explainer video here from 2018:

https://twitter.com/PeterWSinclair/status/1746208469248541152

However, there is some scientific disagreement about this theory. Studies like this one from 2021 have claimed the influence of ice loss on winter weather is quite weak - that if anything its effect was modest and intermittent. meetingorganizer.copernicus.org/EGU21/EGU21-96…

Yet this 2021 study found that winter weather was indeed being affected by a wavier jet stream (though the study doesn’t mention melting ice as a cause): agupubs.onlinelibrary.wiley.com/doi/10.1029/20…

What does the IPCC say? The most recent Assessment (AR6) covers this debate at length (within Cross Chapter Box 10.1). They do indeed refer to it as “a topic that has been strongly debated” and note different sub-theories explaining cause and effect in various ways.

Finally, the IPCC concludes that while there’s some good evidence out there of an association between Arctic warming and mid-latitude weather, we still don’t have a clear understanding of exactly what’s going on.