World3
In the context of the model, since land is finite, and industrial output required to produce fertilizer and other agricultural inputs can not keep up with demand, there necessarily will be a food collapse at some point in the future.
The "reference run" is the one that "represent the most likely behavior mode of the system if the process of industrialization in the future proceeds in a way very similar to its progress in the past, and if technologies and value changes that have already been institutionalized continue to evolve.
In the book Groping in the Dark: The First Decade of Global Modelling,[5]: 129 Donella Meadows (a Limits author) writes: We have great confidence in the basic qualitative assumptions and conclusions about the instability of the current global socioeconomic system and the general kinds of changes that will and will not lead to stability.
[6]: 905–908 Czech-Canadian scientist and policy analyst Vaclav Smil disagreed with the combination of physically different processes into simplified equations: But those of us who knew the DYNAMO language in which the simulation was written and those who took the model apart line-by-line quickly realized that we had to deal with an exercise in misinformation and obfustication rather than with a model delivering valuable insights.
Lumping together (to cite just a few scores of possible examples) highly substitutable but relatively limited resources of liquid oil with unsubstitutable but immense deposits of sedimentary phosphate rocks, or short-lived atmospheric gases with long-lived radioactive wastes, struck me as extraordinarily meaningless.
[7]: 168 He does however consider continuous growth in world GDP a problem: Only the widespread scientific illiteracy and innumeracy—all you need to know in this case is how to execute the equation
—prevents most of the people from dismissing the idea of sustainable growth at healthy rates as an oxymoronic stupidity whose pursuit is, unfortunately, infinitely more tragic than comic.
[9]: 4–5 ...[We] come to the well-known study, Limits to Growth, published under the sponsorship of the 'Club de Rome' - an influential body of private individuals.
A shining example of this is the Montreal Protocol (1987) that limited the industrial production of fluorocarbons that damage the ozone layer and generated the 'ozone hole' over Antarctica.
The publication of Limits to Growth has greatly contributed towards creating the general willingness of governments to consider such issues.
Technological developments have also lead to improvements in the efficiency of the use of energy and other resources, but, most importantly, the warnings from Malthus onward have finally had their effect as may be seen from the population-limiting policies followed by China and, more hesitantly, by India.
Writing in the journal Global Environmental Change, Turner notes that "30 years of historical data compare favorably with key features of the 'business-as-usual' scenario called the 'standard run' produced by the World3 model".
[10] A number of researchers have attempted to test the predictions of the World3 model against observed data, with varying conclusions.
One of the more recent of these, published in Yale's Journal of Industrial Ecology,[11] found that current empirical data is broadly consistent with the 1972 projections, and that if major changes to the consumption of resources are not undertaken, economic growth will peak and then rapidly decline by around 2040.
