A Change Is a Change Is a Change - or Is It? Reframing Transition Scenarios through Socio-Metabolic Substitution

Not every change amounts to a transition. Renewable capacity, electric vehicles, recycling, and other lower-impact alternatives may expand without substantially displacing the high-throughput systems they are expected to replace. This Perspective develops socio-metabolic substitution as an analytical approach for examining that distinction. It proposes a sequence that begins by confronting long-term system trajectories with sustainability objectives to identify a transition gap, then maps a substitution space of alternatives capable of providing similar services with lower material and energy requirements. Effective substitution is assessed through three linked questions: do absolute resource pressures decline, is access to socially necessary services maintained or improved, and does the system being replaced actually contract? The Perspective argues that this distinction also matters for how transitions are modeled: starting from observed practices, services, stocks, and flows may reveal forms of substitution that remain obscured by approaches centered on aggregate demand or technology deployment. Socio-metabolic substitution is therefore presented as a way to make replacement, rather than mere addition, analytically visible – and to ask whether a change is really a transition, or simply appears as one.