World3 BAU2, a scenario from a 2020 update by researcher Herrington to the classic 'Limits to Growth' computer model.
It is the specific model path that real-world data has actually been following.
The update found that empirical data tracks the 'BAU2' scenario (collapse driven by pollution) and the technology-cost scenario, rather than the original path driven by running out of resources, pointing to an industrial plateau around the 2030s.
It matters because it refines the old collapse forecast, showing the likely squeeze comes from pollution and cost, not simple scarcity, and puts a rough date on the plateau.