Having finally emerged from a winter that made my hometown of Pittsburgh resemble a scene from the film Doctor Zhivago, I'm not inclined to put Al Gore's dire warnings about global warming at the top of my worry list. As Los Angeles writer Jennifer Ginsberg puts it, with Iran on its way to acquiring nuclear weapons, are plastic bags actually the gravest threat to our way of life? And yet, assuming there is a long run, we don't want the free world overrun with landfills, do we?