Fig. 5. Feasible per capita in-use stocks of steel and cement in 2050 compared to the current levels across four income groups.

a Steel. b Cement. Current in-use stock levels for steel and cement are based on the literature²⁹ and divided into four income groups with reference to the World Bank classification. The most populous countries in each income group (i.e., the United States, China, India, and Ethiopia) are presented separately from the overall distribution. The levels of minimum requirements to satisfy basic human needs are based on the literature²⁹.