The polar vortex used to fence in cold Arctic air masses and keep them over the pole. Not any more. Why it’s getting unstable was shown earlier this year by our PhD student Marlene Kretschmer: https://t.co/2UCEo2i7ys #globalwarming

— Stefan Rahmstorf (@rahmstorf) December 31, 2017

Irony of ironies—the #RedSouth will have real winters for the foreseeable future, thanks to the same #GlobalWarming that will make it an ever less-livable place in the summers. This is not good—there aren’t that many plants that can handle an actual winter AND US-south summers. https://t.co/1rJUOYYqEu

— (((Chrysi Cat))) (@chrysicat) January 1, 2018