In a prior study, I introduced a simple economic growth model designed to be
consistent with general thermodynamic laws. Unlike traditional economic models,
civilization is viewed only as a well-mixed global whole with no distinction
made between individual nations, economic sectors, labor, or capital
investments. At the model core is an observationally supported hypothesis that
the global economy's current rate of primary energy consumption is tied through
a constant to a very general representation of its historically accumulated
wealth. Here, this growth model is coupled to a linear formulation for the
evolution of globally well-mixed atmospheric CO2 concentrations. While very
simple, the coupled model provides faithful multi-decadal hindcasts of
trajectories in gross world product (GWP) and CO2. Extending the model to the
future, the model suggests that the well-known IPCC SRES scenarios
substantially underestimate how much CO2 levels will rise for a given level of
future economic prosperity. For one, global CO2 emission rates cannot be
decoupled from wealth through efficiency gains. For another, like a long-term
natural disaster, future greenhouse warming can be expected to act as an
inflationary drag on the real growth of global wealth. For atmospheric CO2
concentrations to remain below a "dangerous" level of 450 ppmv, model forecasts
suggest that there will have to be some combination of an unrealistically rapid
rate of energy decarbonization and nearly immediate reductions in global
civilization wealth. Effectively, it appears that civilization may be in a
double-bind. If civilization does not collapse quickly this century, then CO2
levels will likely end up exceeding 1000 ppmv; but, if CO2 levels rise by this
much, then the risk is that civilization will gradually tend towards collapse
