Economic gloom fast engulfing the US economy contains at least one reason for hope. The new attention it forces onto cost might keep the country from rushing into peril over global warming.Politically, sad as it is to say, the global-warming debate is over in the US. All candidates with any hope for winning the presidency support mandatory limits on emissions of greenhouse gases, whether or not the measures offer reasonable prospect for affecting global average temperature. All candidates, in other words, support the imposition of certain cost in pursuit of very uncertain benefit against the crucial metric of measured temperature. They all want the government to set limits on emissions of...