Population projections provide a valuable toolbox for thinking about the implications of upcoming trends and shifts in population size and structure, which are crucial for understanding various global economic, environmental, societal, and geopolitical developments that significantly depend on human actions. As a result, gaining insights into the future of the global population, in terms of both size and composition, is essential for strategic policy formulation. Most national statistical offices regularly develop population projections. Additionally, some organizations implement population projections at the global level, employing a wide range of methods. In one way or another, these projections rely on expert opinions to come up with assumptions concerning future fertility, mortality, and migration, following various scenarios. These projections are used by different stakeholders, but it is often unclear what assumptions were made and how they were constructed. That is why IIASA and the United Nations Population Division, two of the world's leading producers of population projections, have joined forces with the JRC to conduct a study on what experts think about the determinants and drivers of future population growth, by creating a survey addressed to them. In this report, we document the results of the online survey that was conducted in 2023. A total of 237 respondents, primarily members of the main demographic associations shared their opinions on 240 arguments/statements related to future trends and drivers of fertility, mortality, immigration, and emigration, as well as on the policy consequences of key demographic megatrends. They also provided numerical estimates of future fertility and life expectancy levels in 2050 and 2100, with 80% confidence intervals. It is worth noting that the participation and geographical coverage of the respondents do not allow this survey to be considered representative for country specific analysis. Nevertheless, it does offer valuable insights into the demographic challenges of the future, their drivers, uncertainties, and potential consequences.
