The climate change debate may have turned an important corner. Sir Nicholas Stern’s report not only put a price tag on global warming, but also argues for an economically viable solution. But will humanity act in time?

The day the world’s climate changed was a Monday — Monday of last week, to be more precise, at exactly 10 a.m. That was when a gray-haired man with frameless glasses stood before the press to deliver a clear but alarming message. Now, his message having been delivered, no one can claim not to know the true extent of the damage each individual has been doing to the world.

The core of that message was a number that immediately drove up the planet’s perceived temperature: 5.5 trillion. Sir Nicholas Stern has attached a figure to a phenomenon that is little more than a set of vague concepts for most people. He converted complex physical processes into a unit of measure that directly affects people’s daily lives: money. … More