The World3-Modell is a cybernetic computer simulation, in order to investigate the reciprocal effects between factors such as population, industrial growth, food production and their influence on possible borders in ecological systems of the earth. It was originally developed on behalf club the OF Rome under guidance by Dennis L. Meadows and Randers. The results won from it were published in the book the borders of growth.

The model was documented in the book Dynamics OF Growth in A finite World. It added new characteristics to Jay W. Forrester's World2 model. From some smaller optimizations of the original World3 of model resulted the World3/91-Modell, which is used in the book the new borders of growth, and finally by further smaller changes the World3/2000 model developed. It last became in again updated form for the 2004 study of limit ton of Growth appeared: The 30-Year update of Meadows et al. used.

Model

The model consists of several interacting parts. The main parts are the food production system, industrielle the system, the population system, the system of the not renewable raw materials and the environmental pollution system.

Agricultural system

In this subsystem there is to country and fertilizer. Both will needed for an effective agriculture and all the more to country and/or fertilizer at the disposal is, all the more food can be produced. According to this model there must be sometime a food scarceness, there bewirtschaftbares country finally is and likewise the necessary industrial production, in order to produce fertilizers. The thus producible quantity of food cannot keep up with the demand step of a constantly growing population of world.

Not renewable raw materials

The subsystem over the not renewable raw materials possesses the acceptance that the total quantity of raw materials is finite (approx. 110 times the consumption of 1990 in the World3/91 model). These supplies can be exhausted and served then as input size for the other subsystems of the model. A further important acceptance of this model is that the raw material extraction becomes increasingly ever more difficult at first relatively easily, but.

Criticism of the model

The World3 model was suspended much criticism. Both the creators of the model, some economists as well as further completely different sources practiced and practice criticism to it.

One of the main points of criticism of the model is that the reality of the world was not correctly forecast starting from the first publication of the model into the 1970er years. This criticism is not in the general one wrongly, there for example the main forecast (exceed the growth borders with following collapse) in the standard run of the model the year ago 2015 occurs. To the other forecasts something similar applies. The model predicts that mankind has to count approximately one century after the publication of the book i.e. 2072 on ignoring the fundamental borders economic growth on extremely serious ecological problems. These problems will begin according to the model to become obvious in the 2030ern and 2040ern. Besides some the other runs dates for at the beginning of the collapse, even later in the model, forecast. The 1992 wrote book, the new borders of growth describe several values of the model, which had to be changed, in order that are for this time observed to represent to be able. None of those changes was pulled sufficiently, in order the general qualitative conclusions like it by the group around Meadows is, to be changed.

Since the inventors of the model thereby are most familiar, their criticism is considered as most relevant. In the book Groping into the dark: The roofridge Decade OF global Modelling (page 129) writes Donella Meadows correspondingly:

We have large confidence to the fundamental qualitative acceptance and conclusions of the model in points of the instability of the present global socialeconomic system and the general kinds of changes, which lead in the view to stability or do not lead. We have relatively large confidence into the feedback loop structure of the model, however with some exceptions, which I specify down. We have a mixed measure of confidence to the numeric parameters of the model; some are well-known physical or biological constants, which probably hardly change, some are statistically derived social indices, their probability that they change, is not small and some is genuine assumptions, which meet hopefully the order of magnitude. The structural acceptance in World3, the doubt and enough are sensitive, in order to be from affair to, are:

the constant expenditure for capital (accepts no removing of the capital),

the residiale nature of the Investmentfunktion

the generally insignificant contribution of the worker for overall function

However Donella Meadows hardly saw problems in the fundamental qualitative acceptance, so that these by other authors were examined.

The most detailed criticism of the model is in the book Models OF Doom: To find A Critique OF the of limit ton of Growth.

Both Julian Lincoln Simon and Lomborg discussed the acceptance, which the model contains. The first acceptance, which they criticize, is the acceptance of finite natural supplies. The model contains a hard border and no method of changing a raw material to Ersatz.Des a further one states it that the borders of the agricultural system are invalid, since they are based on the limited quantity ashore. However this is a contradiction, since the model permits that more food with the same quantity ashore however with increases of other agricultural inputs (as fertilizers) it can be achieved.

The points of criticism at the model must be considered, however even if the acceptance of finite natural resources from the model are removed, prognosticate the model a collapse due to the environmental pollution. The model cannot apply therefore yet as disproved.

When refutation of the criticism became argued that Julian Simon, an economist and Lomborg, a political scientist, who would not have supplied necessities scientific proof. Both authors wrote books, which strongly of environmental science-learn were criticized.

Literature

• Dennis L. Meadows, Donella Meadows, Erich tooth, Peter Milling: The borders of growth - reports club of the OF Rome for the situation of mankind. German publishing house, Munich 1972, ISBN 3-42-102633-5
• Dennis L. Meadows et al.: The new borders of growth. Rowohlt, Reinbek 1993, ISBN 3-49-919510-0
• Dennis L. Meadows et al.: Limit ton of Growth: The 30-Year update. Chelsea Green Publishing company 2004, ISBN 1-93-149858-X (English)

Resuming literature

• Karsten heart man, Caroline Seibert: New perspectives for the ecological growth criticism (pdf 376 KB), 2005
• Athanasios Karathanassis: Nature destruction and capitalistic growth. VSA, Hamburg 2003, ISBN 3-89-965018-2
• Friedrich Schmidt Bleek: How much does environment need The measure for ecological managing. Basel 1994, ISBN 3-76-432959-9
• Bob Woodward and Andrew Simms: Growth Isn't Working. London 2006, ISBN 1-90-488206-4, (pdf, 1.2 MT) (English)

Popular-scientific literature

• Johannes M. Waidfeld: Growth, the mistake, prosperity, a social view, Fischer & Fischer media AG, Frankfurt 2005, ISBN 3-89950-076-8

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