This is the fourth post in a mini-series on the rebound effect. Here are posts one, two, and three.

Let's briefly review what we've covered so far in my rebound series:

1. Climate change means we need to reduce greenhouse gas emissions, a lot, beginning immediately.
2. There are two ways to reduce GHG emissions from energy: increase low-carbon energy supply and/or decrease total energy consumption.
3. Ramping up clean energy supply can't be done fast enough to keep us within our carbon budget, certainly not in the short- to mid-term, if at all. So we've got to use less energy.
4. There are two ways to reduce energy demand: reduce the energy intensity of the global economy and/or reduce the growth of the global economy.
5. Substantially reducing global energy intensity turns out to be extremely difficult, thanks in part to the rebound effect.
6. If energy intensity can't be reduced quickly enough, then the only answer left (other than failing to stabilize global temperature at all) is slowing GDP growth. Yikes.

So where does this leave us? In my mind, two big questions remain, regarding Nos. 5 and 6.