  For those concerned with the long-term value of their accounts, it can be a
challenge to plan in the present for inflation-adjusted economic growth over
coming decades. Here, I argue that there exists an economic constant that
carries through time, and that this can help us to anticipate the more distant
future: global economic wealth has a fixed link to civilization's overall rate
of energy consumption from all sources; the ratio of these two quantities has
not changed over the past 40 years that statistics are available. Power
production and wealth rise equally quickly because civilization, like any other
system in the universe, must consume and dissipate its energy reserves in order
to sustain its current size. One perspective might be that financial wealth
must ultimately collapse as we deplete our energy reserves. However, we can
also expect that highly aggregated quantities like global wealth have inertia,
and that growth rates must persist. Exceptionally rapid innovation in the two
decades following 1950 allowed for unprecedented acceleration of
inflation-adjusted rates of return. But today, real innovation rates are more
stagnant. This means that, over the coming decade or so, global GDP and wealth
should rise fairly steadily at an inflation-adjusted rate of about 2.2% per
year.
