Forget about the proverbial “Plan B.”

A Canadian professor and social scientist says that given climate trends and “virtually no chance of a breakthrough” on climate policy, it’s time to start thinking “Plan Z.”

Writing from abroad the Canadian Coast Guard’s Louis S. St-Laurent on a recent research trip, Thomas Homer-Dixon of the Balsillie School of International Affairs, in Waterloo, Canada, wrote that the changing climate — as illustrated by “devastating mudslides in China and weeks of searing heat in Russia” — contrasts with “nearly stopped” political action in nations’ capitals worldwide.

Given the global lobbying clout of coal and oil interests and the difficulty many people have in addressing what has become “an ideologically polarizing issue,” he wrote in an August 23 Op-Ed ( “Disaster at the Top of the World” ) in The New York Times, “we’ll almost certainly need some kind of devastating climate shock to get effective climate policy.”

Homer-Dixon doesn’t see that as such a far-fetched possibility at all. He points to the prospects for altered storm tracks and rainfall patterns and impacts on grain and crop production as real concerns.

“Policymakers need to accept that societies won’t make drastic changes to address climate change until such a crisis hits,” he cautioned, while urging progress on substantive contingency plans — Plan Z — in the meantime.

Pointing to an “easy to imagine” climate shock in North America, he paints a portrait of a parched American Southeast or Southwest and “news clips of cars streaming out of Atlanta or Phoenix [that] might finally push our leaders to do something serious about climate change.” His prescribed Plan Z in that case might involve guidelines for regional and local leaders on how to respond, advance decisions on allocations of limited water supplies, lines-of-responsibility for local law enforcement interests and emergency responders and federal agencies and the military.

“We need to be ready,” Homer-Dixon cautions … even if politicians and policymakers worldwide aren’t yet ready to do their parts.