World4 is a predictive model for world population. Population has grown hyper-exponentially in the last millenium, with the doubling time decreasing from 900 years  in 1000 CE to a minimum of ~35 years in 1963 CE. Technology is defined as that which decreases the death rate and/or increases the effective birth rate (i.e. by decreasing infant mortality). Technology grows exponentially, therefore population fits a hyper-exponential (exponent within an exponent). Models for the end of growth are explored using equations that express the ways humans are depleting Earth's biocapacity, the nature of resource depletion, and the relationship between natural resources and human carrying capacity. This simple model, containing just two closed systems, captures the subtle shifts in the population trajectory of the last 50 years. Specifically, hyperexponential growth has given way to subexponential growth. A peak is predicted for the time around 2028.  [Bystroff, C. (2021). Footprints to singularity: A global population model explains late 20th century slow-down and predicts peak within ten years. PloS one, 16(5), e0247214.]

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

The Limits to Growth Archetype demonstrates the manner in which initial growth may be slowed over time by a limiting factor.

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth. See also Archetypes.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

The Limits to Growth Archetype demonstrates the manner in which initial growth may be slowed over time by a limiting factor.

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth. See also Archetypes.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.

An element of Perspectives: The Foundation of Understanding and Insights for Effective Action. Register at http://www.systemswiki.org/

Simlation Scenario is below:

Scenario2:Natural resources usage normal 1->0.25

Scenario3:Natural resources usage normal 1->0, Pollution normal 1->0.1 or new natural resources usage 0.25->0

The limits to growth structure is based on the basic growth structure. And, as should be obvious, nothing grows forever as growth requires resources. Those required resources become a limits to growth.

From Jay Forrester 1971 Book World Dynamics, the earlier, simpler version of the World 3 Limits to Growth Model. adapted from Mark Heffernan's ithink version at Systemswiki.