This short post reprises a comment on Kaya’s Identity a few weeks back.
F = P . G/P . E/G . F/E
F is excess global CO2 emissions from human sources
P is global population
G is world GDP
E is global energy consumption
G/P is the GDP per capita
E/G is the energy intensity of the GDP
F/E is the carbon footprint of energy
If we want to get F, total carbon to zero, we have to get one of these four factors to zero.
Assuming that at some stage this century we must drive F (total carbon rate) to zero, this implies at least one of these factors must also be zero. But which ones?
Setting P = 0 is the human extinction plan and I think we can rule that one out. Nonetheless humanity is now entering an entirely new demographic state we have never been in before; many developed nations are now at zero or even negative population growth. This has long term implications well worth exploring in a future post.
Setting GDP/capita to zero (or essentially to pre-industrial levels) is the mass poverty option and not achievable. Even just ‘dialing back’ has significant implications.
Setting the Energy Intensity/GDP to zero is also physically impossible. Otherwise commonly thought of as ‘energy efficiency’ it’s been improving steadily since around the 1960’s and automation in particular has been increasingly applied capturing more and more opportunities. Much of my own career was either directly or indirectly aimed at improving production efficiencies.
This leaves setting the Carbon Footprint/Unit Energy to zero as the only viable option. Ulitmately this means using no fossil carbon whatsoever. There is also an argument that by mid century the need to reduce carbon from the atmosphere will become a compelling need. In other words a negative Carbon rate.
The reason this expression is called an ‘Identity’ is because in many ways the four terms all interact; they’re not independent variables. In this sense the expression is really only telling us that ‘carbon = carbon’, but the value of it is in teasing out these four measurable levers which are all too often conflated and confused.
Next post will look at the population lever, and why it’s fundamental.