Any chance of seeing a chart? If you can't post charts then email it to me - png is best but jpg or tiff will do - and I'll post it.

Euan

Thanks to jmac for his plot. And a comment attached:

Since I did not have accsess to the actual data used for the book's scenarios I reverted to "Graphology", i.e. replotted the non-renewable resources and then measured the slope. Certainly not as accurate as it could have been with the actual data, but I would estimate that the peak is good to about +/- 2.5 years. As you can see, I got a pretty good asymmetrical curve and peak with a steep fall-off after the peak. I also did the same for their scenario 2, double resources, and got a very broad, flat maximum that spanned 2020 to about 2050. I immediately thought of CERA's undulating plateau in the 2030-2040 period.

The basic building blocks of system dynamic models are reservoirs (stocks) and flows, and mechanisms that regulate the flows into and out of the reservoirs. That means that you have to close off the world that you model, otherwise things that enter or leave your system can give unpredictable consequences. And so the real "art" of system dynamics is to divide real –open– systems into closed systems of stocks and flows. Yet in open systems – open, for instance, to flows of information, and/or open to flows of solar energy – new forms of self-organisation can be created, that cannot be captured in a system dynamics model. However, the valuable point of the stock/flow models is of course that it helped to unmask the inconvenient truth of resource depletion. The System Dynamics Society now celebrates its 50th anniversary, without getting much honour for that. Work continues though. Members recently received the first announcement of The First European Energy Workshop, organised by EIfER and LISTO and kindly hosted by EIfER. "This Workshop aims at gathering all SD-practitioners in the energy domain together in a pleasant atmosphere. The workshop shall take place on Thursday and Friday April 17-18 at EIfER in Karlsruhe (Germany)." Contact: Tobias Jaeger (www.eifer.uni-karlsruhe.de), and Luc Van Den Durpel (www.listo.be).