Abstract
Since publication, the Limits to Growth model has received both praise and criticism. One criticism is the model’s sensitivity to input error. We have performed an uncertainty analysis to see in retrospect if the model’s sensitivity was of concern. The results show that standard deviations of output variables are high. The general trends of the variables, however, are predictable, with very similarly shaped trend lines. Trajectories indicating a favourable future for humankind (i. e., without a severe decline in population and resources) stay in areas of low probability.Uncertainty analysis is an important step in determining the reliability of a model. Models which are used to determine policies or guide decisions must be reliable to ensure sound choices are made. The Limits to Growth model by Donella Meadows and colleagues was one of the first computer models to investigate global issues of population growth and resource constraints. The model received much attention and criticism, sometimes being accused of being too sensitive to variations in input parameters. This paper studies the model’s sensitivity to input error through an uncertainty analysis, and examines if this sort of analysis could have affected the debate surrounding the model’s reliability and usefulness. Results showed that given the data used to calibrate the model, the output was susceptible to large variations, with the population variable returning a normalised standard deviation of 0.43. However, despite input error, the trends of the variables remain predictable.
Highlights
Decisions regarding population control, energy consumption, and investment in new technologies would be better informed by study
The data from the study will be presented in a variety of methods, that is, trajectory lines, probability density maps, probability density functions, percentiles and averages, and standard deviations
The main variables examined from the W3 model were human population (POP), fraction remaining of non-renewable resources (NRFR), industrial output per capita (IOPC), food per capita (FPC), crude birth rate (CBR), crude death rate (CDR), and persistent pollution normalised with 1970 levels (PPOLX)
Summary
Decisions regarding population control, energy consumption, and investment in new technologies would be better informed by study-. The parameters in the model were derived by the collection and analysis of a large amount of published data. The results of the model showed current trends of that time would, if continued, lead to a sharp deterioration of the global community’s welfare. To test the behaviour of the model, parameters were changed ronmental policies, or technological advances. A set of ten scenarios were presented in the book The Limits to Growth While each change in parameters resulted in different output, the general shape of trajectories and outcomes closely resembled the standard run, unless drastic changes were made in a specific manner. An example of a drastic change was to limit the number of children per family to two and to set capital investment to equal capital depreciation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: GAIA - Ecological Perspectives for Science and Society
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
