Mr. Godfrey, I think you put your finger on an important question, and I don't think anybody's going to be able to give you a simple answer. But let me give you four ways that are worthwhile thinking about as you think about targets.
One is that you have to bring aspirational top-down targets together with bottom-up targets; you need both. You need to think about how they come together. Kyoto was purely aspirational, top-down. It was out of the air. It was never connected to the ground. You have to do both. If you only stay on the ground you'll be conservative, and you won't move it forward. So that's one thing.
Secondly, you have to take a long-term perspective or a perspective consistent with the scale, the scope, and the weight of the problem. This one needs a longer-term perspective than almost any other, but it needs milestones. It needs something along the way. It needs a trajectory. One of the problems with Kyoto is that we always focus on the gap. Instead of focusing on the gap, we should be looking at the trajectory. What is the slope of that line and what do we need to do with that line if we're going to get there?
Think about a band of possibilities as opposed to a point. If it's a point, it becomes an accounting exercise, a “gee, I met this number” or not. If it's a band of possibilities, it's more consistent with the way the real world actually works.
Finally, whatever target you've set up needs to send a signal that is believable, that is taken seriously by policy-makers and by economic decision-makers. I would argue that one of the problems with Kyoto is that it doesn't have that character.