Dietz, Thomas and Eugene A. Rosa. 1997. "Effects of Population and Affluence on CO2 Emissions.Proceedings of the National Academy of Sciences, USA. 94: 175-179.
The human factors that drive global environmental change have not been extensively examined. Here we estimate the effects of two anthropogenic drivers, population and affluence, on a wide variety of global environmental impacts. Population proportionately increases all types of impacts examined. Affluence typically increases impacts, but the specific effect depends on the type of impact. These findings refocus attention on population and material affluence as principle threats to sustainablity and raise questions about predictions of an ameliorating effect of rising affluence on impacts.
We developed a stochastic version of the Impact = Population•Affluence•Technology (IPATA) model to estimate the effects of population, affluence, and technology on national CO2 emissions. Our results suggest that, for population, there are diseconomies of scale for the largest nations that are not consistent with the assumption of direct proportionality (log-linear effects) common to most previous research. In contrast, the effects of affluence on CO2 emissions appear to reach a maximum at about $10,000 in per-capita gross domestic product and to decline at higher levels of affluence. These results confirm the general value of the IPAT model as a starting point for understanding the anthropogenic driving forces of global change and suggest that population and economic growth anticipated over the next decade will exacerbate greenhouse gas emissions.