Researchers identify 26 past scares analogous to the global warming alarm.Polls show that roughly one person in two is concerned about manmade global warming. Why? Because vivid, alarming forecasts, even those based on weak foundations, are persuasive. For a while at least.We’ve seen this many times before. Take the alarm over mercury in fish: in 2004, an Environmental Protection Agency employee warned that 630,000 babies per year were born at risk of brain and nervous system damage due to “unsafe” levels of mercury in their mothers’ blood. Expectant mothers were discouraged from eating fish.Japan consumes a lot of fish, and...