A few weeks ago, I posted this diary reporting on a new paper that equated the concept of economic fairness to the thermodynamic concept of entropy: both are states of minimum instability. The interesting result was that while the bottom 90% of earners follow an income distribution that entropy suggests is fair, the CEO's of top American corporations are overpaid by 100 times the fair amount.
Now from a different quarter, another scientist has applied thermodynamic concepts to the economy. And not just to one part of the economy, but to human civilization as a whole. Tim Garrett's goal was to reduce the large uncertainties of the IPCC's climate change projections, which must rely on guesswork regarding the future state of the world economy and future carbon emissions.
Garrett's surprising results:
We may be in even bigger trouble than we thought.
And we may be pushing the wrong strategies to get out of it.
Links:
News article, University of Utah
Abstract in Climatic Change
Full peer-reviewed paper. Climatic Change November 21, 2009. DOI 10.1007/s10584-009-9717-9 (pdf, 433 K)
The critical details of Garrett's conclusions are these:
- The ratio of energy use to the total value of civilization (i.e., the sum total of past global economic activity) is constant over time. Garrett computes this constant at about 10 milliwatts per 1990 dollar. Garrett tested this thesis using UN statistics for the period 1970-2005, plus a few historical estimates going back as far as 1 AD; he found that the same constant fits at all epochs. In other words, thermodynamic equations seem to hold when we consider our entire human civilization as one large thermodynamic heat engine.
Basically, we have a certain amount economic activity in a given year, which increases the total value of civilization, which in turn requires more energy (more economic activity) to maintain the following year.
This means that civilization "grows through a self-perpetuating feedback loop in which the consumption rate of primary energy resources stays tied to the historical accumulation of global economic production".
- There is a number that defines the efficiency of this feedback loop (which Garrett calls η), and that number must be positive if civilization is to be maintained. Since the efficiency of this feedback loop controls how fast civilization grows, η is really an expression for the overall rate of return on capital, if we consider "capital" the entirety of human civilization. It turns out that feedback efficiency η is related to energy usage efficiency (called ε) in such a way that if ε increases, so does η. But any increase in η increases the magnitude of the feedback loop, which according to point 1, in turn requires more energy.
- The critical implication of point 2 is that increasing energy efficiency must always increase energy usage. Therefore it is impossible to solve the energy/climate crisis by increases in energy efficiency. Increasing energy efficiency will not -- in fact, cannot -- reduce carbon emissions.
Actually this has been suspected for a long time by some economists. As far back as 1865, W.S. Jevons pointed out that coal usage increased dramatically following Watt's improvements in steam engine efficiency. This is because the lower cost of work created more demand for work than the increased efficiency reduced. Garrett's analysis now shows that this "Jevons paradox" is a general result, i.e. universally true and not tied to any particular technology or economy.
Climate scientists often use the Kaya identity as a way of predicting the magnitude of carbon emissions at some future time. The Kaya identity is an equation that looks like this:
E = p g e f
... where E is carbon emission, p is global population, g is per capita GDP, e is the "energy intensity" of world GDP (the amount of energy consumed per GDP dollar), and f is the "carbon intensity" of energy usage.
Garrett's conclusion implies that energy use is constrained by past economic activity and is therefore population independent. In other words, changes to p and g in the Kaya relation will not change carbon emissions E.
In the past, e and f have only changed slowly. In fact, e may be impossible to change without changing η which, as we have seen, is no help. Therefore, our only real option (other than dismantling civilization itself) is changing f, the carbon intensity of the economy.
In other words, we need to move to non-carbon energy sources as rapidly as possible. Conservation and efficiency are not viable strategies to reduce energy usage or to reduce carbon footprint.
Garrett also computes how rapidly we need to move in that direction in order to stabilize carbon emissions. Perhaps not surprisingly, the number is large.
To reach stabilization, what is required is decarbonization that is at least as fast as the economy’s rate of return. Taking the 2005 value for η of 2.1% per year, stabilization of emissions would require an equivalent or greater rate of decarbonization. 2.1% of current annual energy production corresponds to an annual addition of approximately 300 GW of new non-carbon emitting power capacity—approximately one new nuclear power plant per day.
I understand that this result will not be welcomed by many on the left. But before we cast stones, let us pause to recall how often we have criticized the right for their anti-science views, and how we pride ourselves for being part of "the reality-based community." Therefore let us take this for what it is: reality.
The fate of the planet may depend on your reaction, and on our policies.
For me, at least, the obvious answer -- perhaps the only answer -- is cheaper, safer, waste-free thorium reactors. If you've never heard of thorium and its many advantages, check out Thursday's diary by OmnipotentEntity, or check out this, this, or this by kossack davidwalters.
Or check out one of these youtube videos:
Thorium in 16 minutes
Thorium in 25 minutes
Google Tech talk on thorium by Dr. Joe Bonometti
Google Tech talk on thorium by Robert Hargraves
Google Tech talk on thorium by Kirk Sorenson