A dominant narrative in the climate change debate is that addressing population is not relevant for mitigation because population is only growing in the poorest countries, whose contribution to global carbon emissions is negligible, while the largest contribution comes from rich countries where the population no longer grows. We conducted an analysis of 30 years of emission data for all world countries showing that this narrative is misleading. Splitting the countries into four income groups according to the World Bank’s standard classification, we found that: (i) population is growing in all four groups; (ii) low-income countries’ contribution to emissions increase is indeed limited; (iii) the largest contribution to global carbon emissions comes from the upper-middle group; (iv) population growth is the main driver of emissions increase in all income groups except the upper-middle one; (v) the successful reduction in per capita emissions that occurred in high-income countries was nullified by the parallel increase in population in the same group. Our analysis suggests that climate change mitigation strategies should address population along with per capita consumption and technological innovation, in a comprehensive approach to the problem.