My model is on global population and its impact on the availability of natural resources. The stocks in my system include food availability, soil resources and water resource availability. One question I believe my model can address is, what are the connections between food availability, soil resources and water resource availability; or in other words, are these stocks influenced equally by variables?  I hope to show a direct correlation between all three of these stocks. Food availability as stated in The Impact of Population Growth on Food Supplies and the Environment stated that, “The continued production of an adequate food supply is directly dependent on ample fertile land, fresh water, energy, plus the maintenance of biodiversity.” As population continues to grow so will the inputs to natural resources including water, fertilizer, and the need to have more available land.  What is more astonishing is that if these natural resources are never completely tapped dry, on a per capita perspective availability these resources will decline on astronomical levels since it has to be split amongst people (Pimental et al, 1996).

The flows in my system include food production,drought, water pollution, and greenhouse gases. I picked drought as a flow since it directly impacts the level of water available. Take for instance in California, the five year drought has caused scarcity and triggered state-wide executive orders to conserve water (California Department of Water Resources, 2017). Drought and water pollution can be affected by the number of people living in a country, which is why I picked these elements as flows. Furthermore food production, water pollution and greenhouse gases have strong influences on the availability of natural resources.

I picked mortality rates, birth rates, water scarcity, and industrial development as my variables. Since birth rates and mortality rates vary depending on the country I picked these as variables on my system since population growth is influenced by these variables.   Impact of Population Growth describes how the U. S. is already being affected by population growth, as stated here, “In populous industrial nations such as the United States, most economies of scale are already being exploited; we are on the diminishing returns part of most of the important curves.”

I have decided to change “developed countries” and undeveloped countries” as stocks to variables since these factors actually act more like variables. One question I hope to address with my model is how developed countries can  reduce their impact on resources? Furthermore, Population growth rate does depend on whether a country is developed versus undeveloped, so a country's level of economic development is more of a variable. I have decided to change food production from a stock to a flow, since it seems to be more of a flow that might affect the level of a stock of available food. I have also changed water scarcity from a stock to a variable because it actually affects the flow of water into an overall stock of fresh drinking water

The upper diagram shows the principal factors that have an influence on the budget deficit and indicates what needs to be done to correct it. But this is not the full story. The diagram below shows that  cutting public expenditure reduces aggregate demand and  increases unemployment. The reduction of aggregate demand  reduces  economic activity which has the effect of reducing  tax revenue.  In addition, the state has to pay out funds as there is a need for more unemployment benefit payments.   The result of these austerity measures  is often the opposite of their intended purpose: they can increase rather than decrease the budget deficit.

There is plenty of empiric evidence to show that this has happened time and time again. For instance, a report from UNCTAD (United Nations Conference on Trade and Development) found that between 1990 and 2000 in all the  cases examined where cutbacks in public spending and tax increases were used, the fiscal situation did not only not improve but worsened. Despite such repeated evidence, unfortunately calls for  austerity measures continue to be heard. 

A single resource is used​ with a constant rate and converted into products in use. After a while, these products become unusable because of aging. The recycling of these unusable products is imperfect, thus the amount of not recyclable resource grows (until a better recycling process is invented).

Diagram to illustrate delay in changing to another product when their is a price increase. 

I propose we grow this sim model (or similar) over time to help ourselves better understand the opposing investment and austerity strategies now being advocated for the U.S. government. The hope is to build as simple a model as possible that subsumes the major underlying feedback loops that probably exist in the mental models of proponents of each of these positions. Starting this model was inspired by this Investment vs. Austerity discussion http://www.linkedin.com/groups/Investment-vs-Austerity-How-can-4582801.S.157876413

I made this model to simulate how a companies revenue will change depending on the lifetime of the appliances it manufactures, in combination with the ratio of repair costs and price. It also shows the accumulation of e-waste.

This is an evolving attempt to illustrate the interconnected nature of the economic assets of Roswell - Chaves County

This model is designed to simulate the outbreak of Covid-19 in Burnie in Tasmania, death cases, the governmental responses and Burnie local economy. 

Rating Matrix of S&P

Ocean/atmosphere/biosphere model tuned for interactive economics-based simulations from Y2k on.

I have tried to capture the unemployment benefits budget in a causal loop diagram. You can make this as extensive as you want, but I have tried to focus on how unemployment benefits are financed and on the main determinants of expenditures and income. I was not (yet) able to 'close te loop' - to build the diagram up from feedback cycles. 
The diagram is in Dutch.

This is a simplification of the Austerity vs Prosperity model in the hope that it will be easier to understand.