First off, I give credit for the word "gnastly" to Jeff Jones of IBM and Charles King, writer of Pund-IT Review. It's not their fault I'm choosing to use the word (which I define as extremely nasty, nasty by nature, perpetually nasty) to describe climate change.
Anyway, the reason I cite Mark Twain is that he is reported to have wisecracked: Everyone always talks about the weather; but no one actually does anything about it.
Mark Twain was wrong. We have spent the last 45 years proving him wrong. We have done something about it. We've made it worse.
The figures I look at are disaster costs, and there I am amazed to find that it has reached the point where it is actually affecting GDP. According to some sources, Hurricane Sandy took 0.2 % off US GDP in 3Q, and will have at least that effect in 4Q, because so much of the US lives in the areas affected (of course, its span of damage was 1200 miles at one point, according to Jeff Masters). Projections were that each increase of, say, 1 degree C would increase average energy in the atmosphere to increase average storm speed by 10 mph, not to mention storm surge and precipitation amounts, which would seem to argue for at least a doubling of disaster costs; well, the average disaster costs for the US at least seem to be closer to a tenfold increase, and James Hansen cites this kind of effect as an unwelcome "surprise" of an underestimate of the effects of global warming.
Of course, at least initially, no negative trend is complete without some positive aspects. Last winter was unusually warm in the US, as one would expect with both the North Atlantic Oscillation tilting the right way and winter temperatures warming about 5 degrees anyway from global warming. On the other hand, that led also to baking summer heat that exacerbated the Midwest and Southern droughts that are still going on.
Last winter's mildness helped the economy. I suspect that this winter we will see alternation of cold/snowy and warm like last year, as according to a study the warmer Arctic air from summer ice melting causes oscillations up and down of the jet stream that carries the relative cold (to us temperate zones) south. Overall, I would guess, a slight plus to the economy. On the other hand, we should anticipate more disaster costs next summer and fall ... And this is just the start of the gnastliness, folks. Another decade or two, ten times as much in disaster costs maybe, a 1-2% hit to GDP, food prices really beginning to be impacted -- if not before then.
Oh, well, we still haven't reached the point where it's on the top of the strategic list for CEOs. Not even close, according to recent IBM surveys.
An old Flanders and Swann describes English weather as "cold and dank and wet" and concludes: "Freezing wet December then ... Bloody January again!" Except for the "freezing" part, I suspect that's what may be coming up. Happy holidays, everyone! It's not gnastly yet!