Turnover in changing urban landscapes: a demographic perspective of diversity at the submunicipal level

In recent decades, migration has played an increasingly central role in population change amid very low fertility and mortality, accelerating population turnover resulting in an unequal increase of diversity across territories and generations, accelerating demographic metabolism, the generational succession driving social change. Residents’ perceptions of these fast changes have been instrumentalized by longstanding conspiracy theories, crystallizing in what is known as the “Great Replacement”. This paper counters such narratives by analysing these demographic processes through the case study of three Spanish Mediterranean cities. We measure these demographic dynamics at sub-municipal levels and across cohorts, assessing diversity not merely as the accumulation of origins but as the relative balance between groups. Results show that in a context of rising inequality and job insecurity for both natives and migrants, fast demographic changes, rather than ethnic replacement, reflect complex population dynamics shaped by cohort structures, local socioeconomic conditions, and urban migration histories. Replacement theories capitalize on negative perceptions of demographic change, attributing it as the cause of public discontent over rising inequality. Exposure to diversity is highest in younger “empty” cohorts and economically vulnerable areas: neighbourhoods shaped by twentieth-century internal migration and central areas undergoing gentrification.