Editing The Limits to Growth (section)

==== Interpretations of the exhaustion model ====
Due to the detailed nature and use of actual resources and their real-world price trends, the indexes have been interpreted as a prediction of the number of years until the world would "run out" of them, both by environmentalist groups calling for greater conservation and restrictions on use and by skeptics criticizing the accuracy of the predictions.<ref>''[[The Skeptical Environmentalist]]'', p. 121</ref>{{failed verification|date=November 2017}}<ref>{{Cite web |title=Chapter 17: Growth and Productivity-The Long-Run Possibilities<!-- Bot generated title --> |url=http://www.oswego.edu/~edunne/200ch17.html |archive-url=https://web.archive.org/web/20101218063522/http://www.oswego.edu/~edunne/200ch17.html |archive-date=18 December 2010 |url-status=dead}}</ref><ref>{{Cite news |date=19 September 2002 |title=Treading lightly |newspaper=[[The Economist]] |url=https://www.economist.com/finance-and-economics/2002/09/19/treading-lightly |url-status=live |url-access=subscription |archive-url=https://web.archive.org/web/20190515052804/https://www.economist.com/finance-and-economics/2002/09/19/treading-lightly |archive-date=15 May 2019}}</ref><ref>{{Cite news |last=Bailey |first=Ronald |date=4 February 2004 |title=Science and Public Policy |work=Reason |url=http://reason.com/archives/2004/02/04/science-and-public-policy |access-date=26 November 2017}}</ref> This interpretation has been widely propagated by media and environmental organizations, and authors who, apart from a note about the possibility of the future flows being "more complicated", did not clearly constrain or deny this interpretation.<ref>{{Cite book |title=Limits to Growth |year=1972 |pages=63 |quote=Of course, the actual nonrenewable resource availability in the next few decades will be determined by factors much more complicated that can be expressed by either the simple static reserve index or the exponential reserve index. We have studied this problem with a detailed model that takes into account the many interrelationships among such factors as varying grades of ores, production costs, new mining technology, the elasticity of consumer demand, and substitution with other resources}}</ref>

While environmental organizations used it to support their arguments, a number of economists used it to criticize ''LTG'' as a whole shortly after publication in the 1970s (Peter Passel, Marc Roberts, and Leonard Ross), with similar criticism reoccurring from Ronald Baily, George Goodman and others in the 1990s.<ref name="Bardi-2011" /> In 2011 Ugo Bardi in "The Limits to Growth Revisited" argued that "nowhere in the book was it stated that the numbers were supposed to be read as predictions", nonetheless as they were the only tangible numbers referring to actual resources, they were promptly picked as such by both supporters as well as opponents.<ref name="Bardi-2011" /> 

While Chapter 2 serves as an introduction to the concept of exponential growth modeling, the actual World3 model uses an abstract "non-renewable resources" component based on static coefficients rather than the actual physical commodities described above.