The United States Energy Information Administration provides projections for how much energy the world can be expected to use over the next few decades. Predicting the future is hard, but I think one has to give them credit for trying. The low, medium, and high economic growth projections shown above are largely just extrapolations of existing trends. Even if there is a curious inflection point around 2030, assuming persistence in trends is not a bad way of going for something as highly aggregated as the global economy.
The simulations use an everything but the kitchen sink philosophy for approaching the problem, representing to the greatest extent possible the myriad forces that drive energy consumption, such as political agreements and national and sectoral competition for a range of energy sources. Just the US macroeconomic module alone has well over one thousand equations.
But, as always, there's more than one way to skin a cat. For my part, I have developed a model for global energy consumption that is almost absurdly simple. It has only a few equations. Nonetheless it manages to produce accurate hindcasts for energy consumption and GDP growth rates with skill scores >90% for a 50 year period between 1960 and 2010 using only conditions in the 1950s to initialize the model.
The key ingredients of the model are only that global energy consumption and wealth can be linked through a constant; that inflation-adjusted global GDP grows global wealth; that the coefficient relating wealth to GDP is a function of past innovation; and, that innovation can be related through thermodynamics to resource availability and rates of decay.
Claiming that civilization can be reduced so simply is admittedly a bit unorthodox. What the model does have going for it is that each of these things is testable and based on physical reasoning.
Of course, the tremendous trade-off with this more holistic view is it offers little to nothing about the details, like how national consumption will change over the coming decades. Understandably, some think it's important to distinguish the U.S. from the rest of the world.
Still, we do still talk about the global economy. And, for an atmospheric scientist trying to link economic growth to climate change, it doesn't matter whether a molecule of carbon dioxide comes from Timbuktu or Trump Tower since CO2 is a long-lived well-mixed gas.
But let's assume that those thousands of equations the EIA uses does get things plausibly right, at least in the big picture. On average, EIA projections see the global demand for energy growing by about 50% over the next 40 years, 0.9% per year on the low end and 1.4% per year on the high end.
Using the aforementioned constant, what is being referred to by others as the Garrett Relation, a trivial prediction of the model I mentioned is that inflation-adjusted global Wealth will also grow by 50% over the same time period.
Some of us might feel a bit disappointed by a real growth rate for our collective assets of just 1% per year, but effectively this is what the EIA projections imply.
I am a bit skeptical they are correct partly because the physically-based economic model also forecasts that there is substantial inertia to existing trends. Between 2000 and 2010, the average growth rate for global energy consumption and real wealth was about 2% per year (although GDP grew faster, closer to 3% per year). A sudden revision downward in growth to 1% would require something fairly dramatic in terms of a reduction to resource availability. If we were to assume for the sake of argument a continuation of the 2% growth rate instead of the EIA's 1%, that would mean that global Wealth would increase by 60% in 40 years.
But whether the increase is 50%, as implied by the EIA, or 60%, as implied by persistence in trends, the future still looks good. Right?
Well, maybe not, at least not for the environment. Even maintaining 1% per year growth will require something that might seem pretty extraordinary: over the course of the next 40 years we will consume as much energy total as the total we consumed in the past 100 years. At 2% growth, that number is more like 140 years.
Energy does stuff. In thermodynamics we call it Work. A lot of stuff has happened in the past century. Consuming the same amount of energy in 40 Years will mean, very roughly, we will do the same amount of Work all over again.
A more advanced concept in thermodynamics is that there is a coupling of energy dissipation with material flows. What this means is that energy is consumed not just to sustain civilization's internal circulations, but to take raw materials from the environment like fish, minerals, and wood. These are used to repair and grow civilization (including by making more of us as people) while leaving behind a big pile of garbage in solid, liquid, and gaseous forms.
We've certainly packed on the pounds over the past century, largely at the sacrifice of the critters and plants on land and the fish in the oceans, while leaving behind an added 100 ppm to the atmospheric concentration of CO2.
What will the world look like when we manage to do the same all over again?
No comments:
Post a Comment