- A consistent exponential growth in emissions
- A consistent improvement in GDP/energy and a mild improvement in energy/CO2
raises the question: can technical efficiency gains reduce emissions? If so, can they do so rapidly enough to prevent catastrophe.
This question has been open since Jevons wrote about the use of coal in the Empire, but it is certainly not cut-and-dried.
In the case of your spotlights, there are several places for a rebound effect:
- You have more spare money; you spend that money on something else, which (perhaps) causes some emissions
- You have avoided using some electricity, lowering the cost of electricity. This renders electricity useful for some other customer for whom it was previously marginal
And so on.
For efficiency gains alone to work, the new technology will have to be astounding enough to reduce the cost of energy below the marginal production cost for all the existing sources, and to allow us to chuck away all of the existing fossil fuel infrastructure without discomfort.
Otherwise we will just use astounding new technology along with all our old technologies, and do more stuff.
Efficiency gains (which will come, and are welcome and necessary) need to be coupled with a political limit on extraction of fuels to avoid this outcome, in my opinion.