Last week a severe storm froze Dallas under a sheet of ice, just in time to disrupt the plans of the tens of thousands of (American) football fans descending on the city for the Super Bowl. On the other side of the globe, Cyclone Yasi slammed northeastern Australia, destroying homes and crops and displacing hundreds of thousands of people.

Some climate alarmists would have us believe that these storms are yet another baleful consequence of man-made CO2 emissions. In addition to the latest weather events, they also point to...