For years, advocates of climate-change legislation have struggled to find a sales pitch that will sway even the most hardened of skeptics. Polar bears, green jobs, urgent pleas to think of the grandkids … none of them have quite done the trick. But recently, a new argument has come to the fore: the national security case for cutting carbon emissions.

Earlier today, congressional Democrats held their second hearing on the national security aspects of climate change in little over a week.