A Brief Anti-Climatic Prognostication

I see where predictions have sped up, for the arrival of the summer when the North Pole is entirely ice-free. They were saying this would happen in 2030; now they are thinking it could be by 2013. I have seen that kind of acceleration in other sorts of predictions in recent years. If I recall correctly, they were predicting that world population would level off at a total number that was much lower than they are now predicting. In the stock market situation of the past year, the extreme pessimists eventually became the moderates, as things became worse than most economists had expected. Today, I see where Paul Krugman says this:

Martin Weitzman, a Harvard economist who has been driving much of the recent high-level debate, offers some sobering numbers. Surveying a wide range of climate models, he argues that, over all, they suggest about a 5 percent chance that world temperatures will eventually rise by more than 10 degrees Celsius (that is, world temperatures will rise by 18 degrees Fahrenheit). As Mr. Weitzman points out, that’s enough to “effectively destroy planet Earth as we know it.”

In light of the slow and scant progress being made on environmental matters across the globe as a whole (factoring in the levels of pollution in China and other developing nations), it seems reasonable to speculate that Weitzman's calculations may have been based upon models that were compatible with the earlier "ice-free by '30" estimate. The recent change to an "ice-free by '13" estimate would presumably speed up the timetables in the studies Weitzman would survey, if he were to start his research over today, or a year from now. That is, we may speculate that a 5% chance of a temperature rise exceeding 18 degrees is now more like 10% or higher. We may also assume that, pending a very fundamental reevaluation of contemporary economic and political priorities -- the sort of thing most likely to be triggered by a global crisis, if at all -- we will remain on course to push the upper edges of the available models for some years to come. Research tends to lag the realities. In current terms, I would speculate, there is now something like a 25% chance that world temperature levels will rise to a point that will severely or entirely curtail life, as we know it, within the next generation or so. Concerted political will to change the momentum in that direction will perhaps not develop for another seven to ten years, when the Arctic will no longer provide its recent summer cooling -- when, that is, summers begin to become unbearable to the point of provoking serious political will. A rapid rise in sea levels could provoke that sort of willpower, but there does not seem to be an ice shelf or chunk large enough to raise sea levels, other than Greenland's, and at present it seems that one will be slow to hit the water. Riots over food shortages due to drought would be another possibility, but that too seems at least several years away in the developed world.