The study by Thomas Dietz and Eugene A. Rosa examines the effects of population and affluence on CO₂ emissions using a stochastic version of the Impact = Population-Affluence-Technology (IPAT) model. The results suggest that for population, there are diseconomies of scale for the largest nations, contrary to the common assumption of direct proportionality. For affluence, the effects on CO₂ emissions peak around $10,000 per capita GDP and decline at higher levels. These findings confirm the value of the IPAT model as a tool for understanding anthropogenic driving forces of global change and suggest that population and economic growth over the next decade will likely exacerbate greenhouse gas emissions. The study also highlights the importance of targeted efforts to shift towards less carbon-intensive technologies and activities to reduce CO₂ emissions.The study by Thomas Dietz and Eugene A. Rosa examines the effects of population and affluence on CO₂ emissions using a stochastic version of the Impact = Population-Affluence-Technology (IPAT) model. The results suggest that for population, there are diseconomies of scale for the largest nations, contrary to the common assumption of direct proportionality. For affluence, the effects on CO₂ emissions peak around $10,000 per capita GDP and decline at higher levels. These findings confirm the value of the IPAT model as a tool for understanding anthropogenic driving forces of global change and suggest that population and economic growth over the next decade will likely exacerbate greenhouse gas emissions. The study also highlights the importance of targeted efforts to shift towards less carbon-intensive technologies and activities to reduce CO₂ emissions.