So, talking about global warming is "alarmism"? Hardly. In many cases, it now turns out, climate reality has been much worse than climate scientists predicted. The Arctic now has ice-free summers, 90 years in advance of predictions. Animals are fleeing to higher elevations twice as fast as models said. Extinction rates are double what was expected, too. 

Science historian Naomi Oreskes puts these discrepancies down to scientists being overly conservative in their predictions. Conservative estimates are thought to protect credibility, Oreskes says, so scientists tend to understate climate impacts. The peer review process also rewards sober assessments, and the media could also contribute by playing down climate findings (say, by letting people talk about "global warming alarmism" over and over on air).