Sub-National Population Projections for Mexico Under the Shared Socioeconomic Pathways (SSPs) in the Context of Climate Change

Abstract

Demographic projections are important for Impacts, Adaptation and Vulnerability (IAV) assessments around climate change. When linked with physical models that delineate alternative outcomes of climate hazards, they lead to enhanced understanding of the location and size of the most vulnerable populations, thereby improving hot-spot analysis for more targeted intervention planning. These demographic projections should be consistent with the Shared Socioeconomic Pathways (SSPs) so their combination with climate projections offers a diverse set of perspectives for climate change risk assessments. Most SSP based projections have been developed at a national level, which mask local-scale heterogeneities. Mexico is a heterogeneous country in terms of climate hazards, demographic characteristics, aging population, and socioeconomic inequalities across regions and states. Thus, we translate the extended SSP scenarios to quantitative demographic assumptions based on regional distinct background conditions. We then use a multi-regional cohort component model to generate SSP-based demographic projections by gender and age for each Mexican state from 2020 to 2100. We also discuss several applications to highlight the added value of using spatially refined demographic projections for IAV analysis and targeted policymaking aimed at improving the resilience of Mexico’s population in relation to climate change. Our projections indicate that, under certain SSPs, domestic migration is a major driver of population change in some states. Our subnational SSP-based demographic projections are the first set of this type of projections for Mexico informed by regional differences in demographic processes, thereby enhancing the evaluation of medium-term and long-term effects of climate change in localized scales.