Change

Friends on Facebook recently posted photos of the thoroughly frozen Great Lakes, and also of the great city of Atlanta gridlocked by unexpected snow. This is certainly not sufficient to disprove climate change: Salt and ice can be used to freeze ice cream, but that's because the ice is being melted by the salt. Conversely, the reconstructed climate record shows variability that to this (admittedly) untutored eye could mean this is as natural as the last million years of Milankovitch cycles.  Although I will agree with Dr. Pournelle that running an open-ended experiment in the only atmosphere available should probably be scaled back if feasible.

However. 

None of that matters with regards to the Crisis. The Strauss and Howe model is ultimately sociological, and within it “Perception is Reality” is a tautology.  If there are enough unusual weather events, people will think it is happening and if enough think it is happening, they will expect and support change. Alternatively, if the events are mostly cooling in nature, the previous claims that pronounced “warming” as the main danger will result in people discounting what happens. Hopefully this would only mean the warnings are ignored.  In the worst case, they could be reversed - say, via a revolt against opaque science, wherein only things explainable to the populace are considered worthy of democratic debate. “If you can't explain it simply you don't understand it,” said Einstein .... in a poster I saw at work once ... and Congress has trouble enough with what it does understand. The S&H model predicts only that a Crisis will occur, and that it is due to people reacting to a (perceived) national threat. There’s no guarantee that the “threat” is the most dangerous one, much less that the people will choose the best response.

For future Prophet generations, let me recommend holding off on demanding immediate change unless the facts are incontrovertible. (Not necessary, of course, for moral claims, as they are normally undecidable - and besides, you wouldn’t listen in that case anyway.) That will help avoid people ignoring ALL early wild claims when SOME of them are proven false. Jenner proved that vaccination worked in 1796 but it took until 1979 for enough support to eradicate smallpox. Roosevelt held off until the Japanese themselves revealed their expansionist aims. It might seem like another second will be too late. Unless you are sure, though, that early pronouncement may do more harm than good.