But there is an important omission in this logic. It stems from the fact that to stop climate change, we need not just to reduce our CO2 emissions, but rather to eliminate them entirely. Once none of our energy comes from fossil fuels, then the climate won’t care how much energy we use.
Of course this isn’t the entire story either. It will take time before we can switch to entirely renewable energy, across all sectors of the economy. So there are two important questions worth investigating:
First, does the energy we save, during this period of transition to purely renewable energy, make much of a difference? Second, will efforts to conserve energy also accelerate the shift to renewable energy, or could they even slow this shift down?
A drop in the ocean
We recently examined the first of these questions.2 The short answer: saving energy makes almost no difference. To meet the targets that scientists and policy-makers have set – limiting climate change to less than 2°C total warming – we need to eliminate emissions in the next twenty to thirty years. The exact deadline for going fossil-free depends on a number of uncertain factors, most importantly whether we believe it will be possible to actively remove CO2 from the atmosphere in the second half of the century.
The climate turns out to be remarkably insensitive, however, to changes in energy efficiency. Under one set of assumptions, which includes current trends in improving energy efficiency, the deadline to go fossil-free is 25 years from now, 2043. With a great deal of effort, we could double the rate of improvement in energy efficiency, from the current trend of 1.5% improvement per year to 3%. How much would that shift the deadline? Only one year, moving it from 2043 to 2044. Saving energy buys us almost no time.