Does material use keep rising as countries get richer, or does it start to fall past some income level, as the Environmental Kuznets Curve would suggest? We started from the panel of Pothen and Welsch (2019) and averaged each country’s data into a cross-section of 141 countries. Then we regressed domestic material consumption and material footprint per capita on GDP per capita, in cubic, quadratic and linear form, for all countries and for OECD and non-OECD countries apart, with robust standard errors.

Only the linear model has significant coefficients, and its slope is positive, steeper for the material footprint than for domestic consumption. So in these data there is no inverted U. The report states the limits: averaging the panel drops country and year effects, and endogeneity is not dealt with. What comes out is a correlation, not a law of growth.