The economy in webDICE uses labor and capital to produce output. The labor supply is assumed to grow with the population. webDICE starts with the current population (just over 6 billion people) and assumes that it will grow to a level that you can set. The default level is 8.6 billion. You can adjust this between 8.0 and 12.0 billion. The following figure illustrates how the growth in population changes for various parameter choices:

Figure 4: Pathway of population for user-choice of asymptotic population.

The population in period $t$, $L(t)$, evolves according to the weighted average formula between the initial population in year 2005, $L(0)$, and the asymptotic population in the last year we consider, $L(Tmax)$: \[ L(t)=[L(t-1)\times L(Tmax)]^{0.5}.\text{ } \]

The model sets the initial population in 2005, $L(0)$, to 6.411 billion and assumes a population adjustment rate of 0.5 per decade. The default asymptotic population, $L(Tmax),$, is set to 8.6 billion; users can choose to adjust this parameter between 8.0 billion and 12.0 billion.