Is Less Really More? Comparing the Climate and Productivity Impacts of a Shrinking Population

• Authors: Mark Budolfson, Michael Geruso, Kevin Kuruc, Dean Spears, and Sangita Vyas
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A smaller human population would produce less carbon emissions, other things equal. This fact has led to the view that an important benefit of the ongoing, global decline in fertility will be reductions in long-run temperatures. Here we assess the magnitude and economic significance of this relationship. We find that it is quantitatively small and, therefore, insignificant relative to other well-documented effects of population growth, including non-rival innovation. This conclusion follows from a key fact of timing: Population sizes would respond to any growth rate changes begun today with a many-decades lag, by which point per capita emissions are projected to have significantly declined. Therefore, the additional warming from any plausibly-sized change in population growth would be small when compared against the resulting long-run productivity impacts. Moreover, even the \textit{sign} of the population-warming relationship is ambiguous when we account for the possibility of aggregate net-negative emissions.

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