Powerful Arctic cyclone last summer was allegedly unprecedented; the most powerful Arctic cyclones tend to come in winter; we think CO2 caused this particular one because (cough mumble)

Great Arctic Cyclone in Summer ‘Unprecedented’: Study | Climate Central

It’s known as the Great Arctic Cyclone, and when it roared out of Siberia last August, storm watchers knew it was unusual. Hurricane-like storms are very common in the Arctic, but the most powerful of them (which are still far less powerful than tropical hurricanes) tend to come in winter. It wasn’t clear at the time, however, whether the August storm was truly unprecedented.

Now it is. A study published in Geophysical Research Letters looks at no fewer than 19,625 Arctic storms and concludes that in terms of size, duration and several other of what the authors call “key cyclone properties,” the Great Cyclone was the most extreme summer storm, and the 13th most powerful storm -- summer or winter -- since modern satellite observations began in 1979.