WOLFRAM SYSTEM MODELER

2nd Scenario

# Wolfram Language

In[1]:=
`SystemModel["SystemDynamics.WorldDynamics.World2.Scenario_2"]`
Out[1]:=

# Information

This is the first modification proposed by Jay Forrester in his WORLD2 model. The utilization of natural resources is reduced in 1970 to 25% of their former value in order to extend their availability.

References:

1. Cellier, F.E. (1991), Continuous System Modeling, Springer-Verlag, New York, ISBN: 0-387-97502-0, 755p.
2. Forrester, J.W. (1971), World Dynamics, Pegasus Communications, 160p.

Simulate the model across 200 years, and plot the state variables as well as the quality of life as functions of the calendar years:

I had to artificially extend some of the tabular functions, because our software complains when an interpolation function attempts an extrapolation.

# Parameters (20)

Population_0 Value: 1650000000.0 Type: Real Description: World population in 1900 Value: 200000000.0 Type: Real Description: Pollution in 1900 Value: 900000000000.0 Type: Real (ton) Description: Unrecoverable natural resources in 1900 Value: 400000000.0 Type: Real (dollar) Description: Capital investment in 1900 Value: 0.2 Type: Real Description: Proportion of capital investment in agriculture in 1900 Value: 0.04 Type: Real (1/yr) Description: Normal birth rate Value: 0.3 Type: Real (dollar) Description: CIAF normalization Value: 15.0 Type: Real (yr) Description: CIAF time constant Value: 0.025 Type: Real (dollar/yr) Description: Normal capital discard Value: 0.05 Type: Real (dollar/yr) Description: Normal capital generation Value: 0.028 Type: Real (1/yr) Description: Normal death rate Value: 1.0 Type: Real (dollar) Description: Capital normalization Value: 1.0 Type: Real (kg/yr) Description: Food coefficient Value: 1.0 Type: Real (kg/yr) Description: Food normalization Value: 135000000.0 Type: Real (hectare) Description: Area of arable land Value: 900000000000.0 Type: Real (ton) Description: Initial natural resources Value: 1.0 Type: Real (1/yr) Description: Normal pollution Value: 3599900000.0 Type: Real Description: Standard pollution Value: 26.5 Type: Real (1/hectare) Description: Normal population density Value: 1.0 Type: Real Description: Standard quality of life

# Outputs (6)

Pop Type: Real Description: World population Type: Real Description: Pollution Type: Real Description: Pollution ratio Type: Real (dollar) Description: Capital investment Type: Real Description: Quality of life Type: Real (ton) Description: Natural unrecoverable resources

# Components (78)

Source1 Type: Source Description: This is the (dummy) source model of System Dynamics Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Level Description: General System Dynamics level Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Sink Description: This is the (dummy) sink model of System Dynamics Type: Source Description: This is the (dummy) source model of System Dynamics Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Level Description: General System Dynamics level Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Sink Description: This is the (dummy) sink model of System Dynamics Type: Const Description: A constant factor Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Gain Description: Gain factor Type: Prod_5 Description: Product of five influencing factors Type: Gain Description: Gain factor Type: Prod_5 Description: Product of five influencing factors Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Gain Description: Gain factor Type: Prod_2 Description: Product of two influencing factors Type: Tabular Description: Tabular function Type: Source Description: This is the (dummy) source model of System Dynamics Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Level Description: General System Dynamics level Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Sink Description: This is the (dummy) sink model of System Dynamics Type: Gain Description: Gain factor Type: Prod_2 Description: Product of two influencing factors Type: Gain Description: Gain factor Type: Tabular Description: Tabular function Type: Gain Description: Gain factor Type: Gain Description: Gain factor Type: Gain Description: Gain factor Type: Prod_3 Description: Product of three influencing factors Type: Tabular Description: Tabular function Type: Division Description: Output first input divided by second input Type: Source Description: This is the (dummy) source model of System Dynamics Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Level Description: General System Dynamics level Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Sink Description: This is the (dummy) sink model of System Dynamics Type: Linear Description: Linear function Type: Gain Description: Gain factor Type: Tabular Description: Tabular function Type: Prod_3 Description: Product of three influencing factors Type: Gain Description: Gain factor Type: Source Description: This is the (dummy) source model of System Dynamics Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Level Description: General System Dynamics level Type: Rate_1 Description: Unrestricted rate element with one influencing variable Type: Sink Description: This is the (dummy) sink model of System Dynamics Type: Gain Description: Gain factor Type: Gain Description: Gain factor Type: Prod_2 Description: Product of two influencing factors Type: Division Description: Output first input divided by second input Type: Gain Description: Gain factor Type: Prod_2 Description: Product of two influencing factors Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Prod_2 Description: Product of two influencing factors Type: Gain Description: Gain factor Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Division Description: Output first input divided by second input Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Prod_4 Description: Product of four influencing factors Type: Tabular Description: Tabular function Type: Tabular Description: Tabular function Type: Gain Description: Gain factor Type: Parameter_Change Description: Parameter variation of WORLD2 model