Economist: OVER the past 15 years air temperatures at the Earths surface have been flat while greenhouse-gas emissions have continued to soar. The world added roughly 100 billion tonnes of carbon to the atmosphere between 2000 and 2010. That is about a quarter of all the CO2 put there by humanity since 1750. And yet, as James Hansen, the head of NASAs Goddard Institute for Space Studies, observes, the five-year mean global temperature has been flat for a decade.
Temperatures fluctuate over short periods,...