11 Feb: NASA: Human and nature dynamics (HANDY): Modeling inequality and use of resources in the collapse or sustainability of societies

* 01 Oct 2012: Motesharrei Rivas Kalnay: Minimal Model for Human & Nature Interaction [PDF; Copy PDF]; 11 Feb 2014: Human and nature dynamics (HANDY): Modeling inequality and use of resources in the collapse or sustainability of societies [PDF; Copy PDF]; Science Direct: Ecological Economics: Human and nature dynamics (HANDY): Modeling inequality and use of resources in the collapse or sustainability of societies; Guardian: 14 Mar 2014: Nasa-funded study: industrial civilisation headed for ‘irreversible collapse’?; 21 Mar 2014: Did Nasa fund ‘civilisation collapse’ study, or not?; Stanford Online: 21 May 2014: Stanford Seminar – Minimal Models of Human Nature Interaction: (1) HANDY: Human and Nature Dynamics and (2) COWA: A Coupled Human-Climate-Water Model.

2012: Abstract: A Minimal Model for Human and Nature Interaction:

There are widespread concerns that current trends in population and resource use are unsustainable, but the possibilities of an overshoot and collapse remain unclear and controversial. Collapses have occurred frequently in the past five thousand years, and are often followed by centuries of economic, intellectual, and population decline. Many different natural and social phenomena have been invoked to explain specific collapses, but a general explanation remains elusive. Two important features seem to appear across societies that have collapsed: (1) Ecological Strain and (2) Economic Stratification.

In this paper, the structure of a new model and several simulated scenarios that offer significant implications are explained. The model has just four equations that describe the evolution of the populations of Elites and Commoners, Nature, and accumulated Wealth. Mechanisms leading to collapse are discussed and the measure “Carrying Capacity” is developed and defined.

The model suggests that the estimation of Carrying Capacity is a practical means for early detection of a collapse. Collapse can be avoided, and population can reach a steady state at the maximum carrying capacity, if the rate of depletion of nature is reduced to a sustainable level, and if resources are distributed equally.

PDF: 2012: Motesharrei Rivas Kalnay: Minimal Model for Human & Nature Interaction

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2014: Abstract: Human and Nature Dynamics (HANDY): Modeling Inequality and Use of Resources in the Collapse or Sustainability of Societies:

Large: 2014_NASA-Sesync_Motesharrei_HANDY
Large: 2014_NASA-Sesync_Motesharrei_HANDY

There are widespread concerns that current trends in resource-use are unsustainable, but possibilities of overshoot/collapse remain controversial. Collapses have occurred frequently in history, often followed by centuries of economic, intellectual, and population decline. Many different natural and social phenomena have been invoked to explain specific collapses, but a general explanation remains elusive.

In this paper, we build a human population dynamics model by adding accumulated wealth and economic inequality to a predator-prey model of humans and nature. The model structure, and simulated scenarios that offer significant implications, are explained. Four equations describe the evolution of Elites, Commoners, Nature, and  Wealth. The model shows Economic Stratification or Ecological Strain can independently lead to collapse, in agreement with the historical record.

The measure “Carrying Capacity” is developed and its estimation is shown to be a practical means for early detection of a collapse. Mechanisms leading to two types of collapses found in history. Collapse can be avoided, and population can reach a steady state at maximum carrying capacity if the rate of depletion of nature is reduced to a sustainable level and if resources are distributed equitably

PDF2014: Motesharrei Rivas Kalnay: Human and Nature Dynamics (HANDY)

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