Birth rates are falling worldwide, in every region. Falling birth rates can be decomposed into two components: (1) an increase in childlessness (i.e., lifetime nulliparity), and (2) fewer children ever born to women who have at least one child (completed cohort fertility among the parous). This...

A smaller human population would emit less carbon, other things equal, but how large is the effect? Here we test the widely-shared view that an important benefit of the ongoing, global decline in fertility will be reductions in long-run temperatures. We contrast a baseline of global depopulation...