Bob, I shouldn't be one who needs further enlightenment relative to non-scientist readers, but I don't get it - specifically in regard to explanation of how the change in variance converts to probability of occurrence independently and combined with change in mean.
Also, Black Swans, at least implicitly, refer to a low probability AND high impact events. Without actual numerical values excessive heat might not be considered black swans in the new climate and not necessarily have very large impacts.
Steve, I probably (high probability) should have just used the first graph with the increase in the mean to illustrate. I was trying to find a graph Tom Karl showed a number of years ago at a conference to show how even a slight shift of the mean in a "normal" curve would increase the probability of heat extremes. Right about the "Black Swan" events. Increasing probability of extended heat waves would sure be high impact. Thanks for reading and feedback