It used to be that the Arctic was always intensely cold and that cold was kept in place in the extreme north. But now the Arctic is having fits of not-so-intensely-cold, and that is screwing up the cold-holding-in-place mechanisms of atmospheric circulation. Some new research is looking at that:
The satellite record since 1979 shows downward trends in Arctic sea ice extent in all months . . . Previous studies have linked changes in winter atmospheric circulation, anomalously cold extremes and large snowfalls in mid-latitudes to rapid decline of Arctic sea ice in the preceding autumn. Using observational analyses, we show that the winter atmospheric circulation change and cold extremes are also associated with winter sea ice reduction through an apparently distinct mechanism from those related to autumn sea ice loss. . . .
So, there are multiple ways that atmospheric circulation is changing. Atmospheric circulation is changing. It's not hypothetical; it's being measured.
There are several root causes at work here.
One of the more fundamental is "albedo flip" which is a fancy term that says, when snow melts and things get darker, they heat up enough to stay that way. There is no going back.
Another is that a warmer, melted Arctic Ocean has less of an ice lid to keep water from evaporating out into the sky. Water vapor is a strong greenhouse gas, so amplifies what warming caused the melting in the first place.
These and a few other things are causing the Arctic to "flip" to a melted and much warmer state. Having warmth where there used to be intense cold wreaks havoc with the physics of atmospheric circulation.
It's time to think about dealing with weather extremes, because there is a certain amount of "runaway" that has begun to happen and will continue until it has run its course. How long that will be depends on whether other runaway processes will be tipped. Odds are this will be the first of a long line of dominoes.
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