Climate change represents one of the most pressing challenges for societies in the 21st century. This special issue of the Vienna Yearbook of Population Research (VYPR) brings together interdisciplinary contributions from 51 authors to explore the demographic dimensions of climate change. In many ways, human populations are at the center of the current climate crisis. On the one hand, anthropogenic forces are responsible for the unprecedented changes in the climate system that are currently being observed. It is the burning of fossil fuels that has significantly increased greenhouse gas concentrations, driving global warming and altering natural climate patterns. On the other hand, human populations are also profoundly affected by these changes, as they are facing increased risks from extreme weather events, rising sea levels and shifting ecosystems, which, in turn, impact livelihoods, food and water security, and health and well-being. This special issue provides a comprehensive overview of both the role of population as a driving force of climate change and the significance of its impacts in the areas of health and mortality, migration, and fertility and reproductive behaviors. In addition to 10 research articles, the special issue features seven debate articles by leading scholars, who provide reflections on the climate-population nexus and the role of demographic science in climate change mitigation. Demography offers a wide range of perspectives and methodological tools to understand and address the climate-population nexus, including in the areas of health and population data, mathematical and statistical modeling, and projections. We advocate for a holistic research perspective that incorporates issues related to increasing climate risks into demographic thinking, and vice versa. A thorough understanding of the intricate relationship between populations, population dynamics and climate change is necessary for the development of effective and equitable mitigation and adaptation strategies that address both global and local challenges over time.