Physical Resources: resource depletion is a major issue, with “nearly 100 billion tons of raw materials” being extracted yearly. Renewables are harvested faster than they can be replenished, and nonrenewables are simply depleted as they are used. This is not something that is widely acknowledged by policy makers. Some important nonrenewables include oil, phosphorus, gold, uranium, and battery materials for renewables. Oil has had innovations in its capture that have delayed its decline, leading to a false sense of security in its longevity. Phosphorus is mined for industrial agriculture and has no good replacements — it is likely to become scarce later this century. The same is true for gold, uranium, copper, silica sand, cadmium, gallium, germanium, lithium, and rare earth elements. What results from this is a need for more investment to sustain output. Usually, more energy can be devoted to make up for the increasing difficulty of obtaining minerals and materials, but as our energy situation becomes precarious, this becomes an untenable path forward. Freshwater (with depleted aquifers and melting glaciers) and soil (degraded through erosion and salinization) are also in danger, which jeopardizes the future of food production.
What the report left out: “Many may think of [the standard run] as a worst-case scenario, in that it did not reflect policy interventions that could slow population growth, pollution, or resource depletion. But really, it was a better-than-worst-case scenario, because it did not reflect the impacts of hard-to-predict events such as the COVID-19 pandemic.” There was also no attempt by the team to model interactions of finance and debt. An analysis of social cohesion was also left out. Climate change was also mentioned but not discussed in depth.
Later re-assessments: The Limits to Growth team produced two subsequent books, Beyond the Limits (1992) and Limits to Growth: The 30-Year Update (2004), both authored by Donella Meadows, Dennis Meadows, and Jørgen Randers. In both follow-up books, the authors concluded that humanity has overshot the limits of what is physically and biologically sustainable, and that overshoot will lead to industrial collapse if we do not act rapidly and effectively to reduce resource extraction, pollution, and population growth. There were also reports done in 2008 and 2020, showing the accuracy of the standard run policy and that economic growth will peak and rapidly decline by around 2040.
What to do—Then and Now: Set the birth rate equal to the death rate in 1975. Reduce consumption per unit of industrial output to ¼ of the 1970 value. Build education, healthcare, and cultural activities over maximizing production. Make food affordable for everyone. Prioritize sustainable agriculture. Improve the designs of industrial capital.
Policy options are highly constrained at this point—any interventions towards what to do will be highly disruptive.