chapter  9
The physical pathway to a steady state economy
ByGraham Turner
Pages 17

When contemplating a steady state economy or sustainable future it’s common to invoke the IPAT equation. The well-known IPAT equation introduced by Ehrlich and Holdren in the 1970s contends that environmental impacts (I) are determined by population size (P), affluence (A, or consumption, i.e. products or services per capita) and economic throughput (T, resources or wastes per product or service) multiplied together (Lutz et al. 2002).