The answer he gave, which was either extremely Finnish or extremely religious, is that it has to come from a genuine, bottom-up commitment. That's why turning off lightbulbs is important. To turn off the light when you leave a room is an act of piety just as much as lighting a candle in church. It has no measurable effect on the crisis at all in itself. It doesn't even have a notable effect on your own electricity bill, and if it ever does, the world economy will be in a dreadful mess. But it is a token of seriousness. It is, if you like, a gesture of faith.
Damn anti-science skeptics questioning their faith!