50+ years of World Models: Collapse, Collapse, Collapse

The Way the Universe Works

Collapse, collapse, collapse. Why?

Above, you see five “standard run” scenarios, starting from the first Limits to Growth calculations of 1972, to very recent ones (there are others; this is just a sample). The model is always the same, “World3” but with updated data, and slightly different assumptions. Note that the population peak has been moving back from ca 2050 in 1972, to around 2030 nowadays. The “pollution” curve, instead, has been moving forward, with the peak shifting to late 21st century, or even later. Both are worrisome, especially the fact that pollution -- which we can identify with global warming -- will keep increasing for nearly one century, before being gradually reabsorbed by the natural system. Note the “Seneca shape” of the peaks: growth is sluggish, but ruin is rapid.

Here is another similar result by Chris Brystroff, but based on different assumptions. It only shows the population trajectory, but it is collapse nevertheless.

Now, a question: why do all these models predict collapse? An accusation that was often made to the authors of the first “The Limits to Growth” report, in 1972, was that collapse was built into the models. Hence, it was said, collapse is an ideological feature that modelers inserted into their models. Just another case of garbage in, garbage out.

The objection cannot be dismissed, because it is basically true. As the authors of “The Limits to Growth” explicitly stated in their report, their models are just quantified versions of their views of the world.

But the objection cuts both ways: consider the typical demographic models, those used by the United Nations to extrapolate global population trends.

Above, you see the results of a typical “cohort-based” demographic model. No collapse. At most, a slow decline, within the uncertainty of the data. It is because, of course, the model does not include the elements that would generate a collapse. Is it ideological? Certainly it is. Also, for the UN modelers, there holds the fact that their models are a reflection of the ways they see the world. The standard demographic models do not go against physics, but choose to neglect some factors that are instead included in dynamic world models.

Is there a way to avoid seeing the future the way we would like it to be? Not easy, because our minds are built in such a way that we tend to extrapolate on the basis of what we know, and we tend to be optimistic regarding the future. Often, way too optimistic.

But there is a way, and it is to base models on physics. It is a point that was rarely made at the beginning of the studies on the global economic system. Yet, it is starting to appear that the assumptions at the basis of these models were NOT just reflections of how the authors saw the world. They were based on physics, even though this point was not explicitly stated.

I am working right now on a paper that quantifies the trajectory of complex systems as a function of the availability of resources and the impact of pollution — the “core” of the LTG world models. It turns out that you CAN generate the growth and decline curves starting from the first two principles of thermodynamics, energy conservation, and entropy generation, together with the Maximum Power Principle (MPP), sometimes said to be the 4th principle of thermodynamics. Here is the abstract (provisional)

The Hubbert curve, originally proposed in 1956 as a phenomenological description of oil-field production, has long resisted derivation from independent principles. We show that the curve emerges as the structural consequence of a thermodynamic chain combining four established results: the Gouy–Stodola theorem on irreversible processes, the Lotka–Odum maximum power principle (MPP) for biological energy harvesting, the Curzon–Ahlborn endoreversible bound for heat engines operating at maximum power, and the two-stock model of Bardi and Lavacchi (2009) for resource depletion under autocatalytic capital reinvestment. Within this framework, the symmetric bell-shaped Hubbert curve is the prediction of the model in its simplest form, while the asymmetric “Seneca” curves observed empirically arise from named symmetry-breaking terms — capacity depreciation, EROI decline, pollution feedback, and best-first extraction — each with a clear thermodynamic interpretation. The synthesis suggests that the descent phase of fossil-energy civilization is not an empirical curiosity but a thermodynamic prediction, and that its asymmetry is structural rather than accidental.

In the end, collapse is a natural property of those complex systems we call “dissipative structures” — an intuition that Ilya Prigogine had already in the 1960s. So, collapse is not in itself unavoidable, but it becomes so when we decide to overexploit the natural resources that keep the system functioning. It is all right. It is the way the universe works. If you don’t like it, it is useless to complain. Just choose another universe.

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The first three scenarios are from the reports produced by the authors of “The Limits to Growth.”
The paper by Nebel et al. is at https://onlinelibrary.wiley.com/doi/full/10.1111/jiec.13442
The paper by Warm is at https://senecaeffect.substack.com/p/a-new-calculation-of-global-trends
The paper by Chris Bystroff is at this link.