Pie in the sky: A systems dynamic perspective of sustainability [Willard
Fey and Ann Lam, ISSS 1998 Plenary Session, July 22/98]
These notes are a rough transcription,
prepared as each individual presenter and/or commentator spoke at the ISSS
1998 conference. Gaps and errors have likely occurred. For more accurate
citations, please consult the original presenters. These notes have been
contributed to the ISSS by David Ing, of the IBM Advanced Business Institute
(sabi@systemicbusiness.org).
[Plenary session, July 22/98, 9.25 a.m.]
Willard Fey is a co-developer of systems dynamics at MIT, now at Georgia
Tech
Ann Lam is a software engineer at DEC, trained in computer engineer,
system engineering
Tape: electromagnetic radiation from space, recorded by Voyager.
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All passengers on a spacecraft, with 30 miles of atmosphere.
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All life relies on sun: plants and animals.
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Fragile balance of water, soil, light and lifeforms.
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Current human presence is sustainable, consumption growing 4 times every
35 years.
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If consumption did not grow, human world would stop.
From system-dynamics program at MIT.
System dynamics methodology:
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Define the problem.
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Hypothesize the causes
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Model the system
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Synthesize an improved model
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Plan a transition.
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Modify the system
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Evaluate the result
Crucial variable on world human consumption.
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Environment and resources --> world human consumption --> waste and pollution.
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Doesn't show recycling, but figure shows net effect.
Exponential function
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Exponent is straight line on log plot.
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Hyper-exponential is an increasing function in a log plot
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Human population growth is hyper-exponential.
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Compound is hyper-exponential:
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Consumption is the product of an exponential * an exponential.
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per capita consumption * world population
Population doubling time has fallen from 600 years to 34 years, due to
reduction in deaths in early 1900s
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Technology-driven health advances.
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Birth rate is still twice the death rate.
World GDP underestimates consumption: linear in log.
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Stopping population growth will not stop human consumption.
Engineering design: constant negative-coefficient exponentials are simple
feedback relationships.
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Compound hyper-exponential is only in complex human systems.
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Fundamental constraint is system stability.
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Most human systems are design to be unstable (e.g. Internet growth).
Two parameter feedback system.
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In complex systems, stability must be measure in each of the input variables.
If human systems do not stop the growth, an environment catastrophe will
stop it.
Bolero is the quintessential musical exponential.
Diagram: Population causal loops (with arrows)
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Birth flow --> pre-puberty population --> maturation flow --> childbearing
population
Animals have territoriality to limit growth: no mating.
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Technology has broken the bound to the land.
Technology causal loops:
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R&D --> new knowledge and products --> per capita consumption --> world
human consumption
Government / borrowing causal loops
Sustainabilty criteria:
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Must be stable: No exponential growth can be permitted, all positive loops
must have limits.
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Sufficiency: When growth ends, sufficient raw material and environmental
infrastructure must be left to support growth.
Proposals that will not solve the growth:
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Consumption, not population growth is the problem.
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Growth will overwhelm all recycling
Tragic dilemmas:
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Consumption growth will lead to catastrophe.
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Everyone is committed to consumption growth.
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Will precipitate economic, social and military calamities.
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