Don't just do something, stand there! Reflections on the counterintuitive behavior of complex systems, seen through the eyes of System Dynamics, Systems Thinking and simulation.
Replicated by Mohammad Mojtahedzadeh from Alan Graham’s thesis, or created anew with the same inspiration. He created these models in the course of his thesis work on structural analysis through pathway participation matrices. Alan Graham, 1977. Principles on the Relationship Between Structure and Behavior of Dynamic Systems. MIT Thesis. Page 76+ These models are pure … Continue reading “Oscillation from a purely positive loop”
This American Life had a great show on the NUMMI car plant, a remarkable joint venture between Toyota and GM. It sheds light on many of the reasons for the decline of GM and the American labor movement. More generally, it’s a story of a successful innovation that failed to spread, due to policy resistance, … Continue reading “NUMMI – an innovation killed by its host's immune system?”
NASA has an interesting article on the fall of the Maya. NASA-sponsored authors used climate models to simulate the effects of deforestation on local conditions. The result: evidence for a positive feedback cycle of lower yields, requiring greater deforestation to increase cultivated area, causing drought and increased temperatures, further lowering yields. NASA “They did it … Continue reading “Maya fall to positive feedback”
I’m at CNAS’ climate war game listening to Diana Farrell from the McKinsey Global Institute. So far my takeaway from the exercise has been rather gloomy; Farrell presented a more hopeful view, informed by McKinsey’s construction of supply curves for carbon emissions reductions. I found her opening point particulaly critical: don’t wait for energy supply-side silver bullets to save us, when … Continue reading “Climate War Game – A Free Lunch”
No pun intended. Scott Armstrong has again asserted on the JDM list that global warming forecasts are merely unscientific opinions (ignoring my prior objections to the claim). My response follows (a bit enhanced here, e.g., providing links). Today would be an auspicious day to declare the death of climate science, but I’m afraid the announcement … Continue reading “More on Climate Predictions”
Last Year, Kesten Green and Scott Armstrong published a critique of climate science, arguing that there are no valid scientific forecasts of climate. RealClimate mocked the paper, but didn’t really refute it. The paper came to my attention recently when Green & Armstrong attacked John Sterman and Linda Booth Sweeney’s paper on mental models of … Continue reading “Evidence on Climate Predictions”