Simple Health Care Supply and Demand Interactions

That efficiency gains achieved by employing technological solutions often have a negative effect has been known since 1856 when William Stanley Jevons described this counterintuitive situation, which has become known as ‘Jevons Paradox’. This simple graph illustrates this effect. Be it extraction of a mineral or the production of a product, employing technology will make the process more efficient, initially, and lower the price of the product produced. However, the lower prices will increase demand and, therefore, the use of the resources employed. Unless more or better technology is employed, the extra demand is likely to lead to a price increase cancelling the initial beneficial effect, and in addition, the resource may be pushed to exhaustion. The technological fix will have failed. Note, ‘solar’ and ‘wind’ are also subject to a ‘Fixes-that-Fails’ structure, but this requires a separate illustration. 

HANDY Model of Societal Collapse from Ecological Economics Paper 

This simple model will attempt to demonstrate how modern civilization's groundwater practices are unsustainable and how they are affected by the changing climate.

Fig 3.1 from Jorgen Randers book 2052 a Global Forecast for the Next Forty Years

This model simulates the growth of carp in an aquaculture pond, both with respect to production and environmental effects.

Both the anabolism and fasting catabolism functions contain elements of allometry, through the m and n exponents that reduce the ration per unit body weight as the animal grows bigger.

The 'S' term provides a growth adjustment with respect to the number of fish, so implicitly adds competition (for food, oxygen, space, etc).

 Carp are mainly cultivated in Asia and Europe, and contribute to the world food supply.

Aquaculture currently produces sixty million tonnes of fish and shellfish every year. In May 2013, aquaculture production overtook wild fisheries for human consumption.

This paradigm shift last occurred in the Neolithic period, ten thousand years ago, when agriculture displaced hunter-gatherers as a source of human food.

Aquaculture is here to stay, and wild fish capture (fishing) will never again exceed cultivation.

Recreational fishing will remain a human activity, just as hunting still is, after ten thousand years - but it won't be a major source of food from the seas.

The best way to preserve wild fish is not to fish them.

Simple box-model of the global carbon cycle

HANDY Model of Societal Collapse from Ecological Economics Paper 

The theory underlying the digital sustainability platform

This model incorporates several options in examining fisheries dynamics and fisheries employment. The two most important aspects are the choice between I)managing based on setting fixed quota versus setting fixed effort , and ii) using the 'scientific advice' for quota setting  versus allowing 'political influence' on quota setting (the assumption here is that you have good estimates of recruitment and stock assessments that form the basis of 'scientific advice' and then 'political influnce' that desires increased quota beyond the scientific advice).