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The projected size and spatial distribution of the future population are important drivers of global change and key determinants of exposure and vulnerability to hazards. Spatial demographic projections are widely used as inputs to spatial projections of land use, energy use, and emissions, as well as to assessments of the impacts of extreme events, sea level rise, and other climate-related outcomes. To date, however, there are very few global-scale, spatially explicit population projections, and those that do exist are often based on simple scaling or trend extrapolation. Here we present a new set of global, spatially explicit population scenarios that are consistent with the new Shared Socioeconomic Pathways (SSPs) developed to facilitate global change research. We use a parameterized gravity-based downscaling model to produce projections of spatial population change that are quantitatively consistent with national population and urbanization projections for the SSPs and qualitatively consistent with assumptions in the SSP narratives regarding spatial development patterns. We show that the five SSPs lead to substantially different spatial population outcomes at the continental, national, and sub-national scale. In general, grid cell-level outcomes are most influenced by national-level population change, second by urbanization rate, and third by assumptions about the spatial style of development. However, the relative importance of these factors is a function of the magnitude of the projected change in total population and urbanization for each country and across SSPs. We also demonstrate variation in outcomes considering the example of population existing in a low-elevation coastal zone under alternative scenarios.

The global population is aging at the same time as heat exposures are increasing due to climate change. Age structure, and its biological and socio-economic drivers, determine populations’ vulnerability to high temperatures. Here we combine age-stratified demographic projections with downscaled temperature projections to mid-century and find that chronic exposure to heat doubles across all warming scenarios. Moreover, >23% of the global population aged 69+ will inhabit climates whose 95th percentile of daily maximum temperature exceeds the critical threshold of 37.5 °C, compared with 14% today, exposing an additional 177–246 million older adults to dangerous acute heat. Effects are most severe in Asia and Africa, which also have the lowest adaptive capacity. Our results facilitate regional heat risk assessments and inform public health decision-making. By 2050 > 23% of the global population aged 69 + will live in climates with acute heat exposure– the 95th percentile of the distribution of maximum daily temperatures–greater than the critical threshold of 37.5C, compared with 14% in 2020, an increase of 177–246 million older adults exposed to dangerous acute heat.

The human population is at the centre of research on global environmental change. On the one hand, population dynamics influence the environment and the global climate system through consumption-based carbon emissions. On the other hand, the health and well-being of the population are already being affected by climate change. A knowledge of population dynamics and population heterogeneity is thus fundamental to improving our understanding of how population size, composition, and distribution influence global environmental change and how these changes affect population subgroups differentially by demographic characteristics and spatial distribution. The increasing relevance of demographic research on the topic, coupled with availability of theoretical concepts and advancement in data and computing facilities, has contributed to growing engagement of demographers in this field. In the past 25 years, demographic research has enriched climate change research-with the key contribution being in moving beyond the narrow view that population matters only in terms of population size-by putting a greater emphasis on population composition and distribution, through presenting both empirical evidence and advanced population forecasting to account for demographic and spatial heterogeneity. What remains missing in the literature is research that investigates how global environmental change affects current and future demographic processes and, consequently, population trends. If global environmental change does influence fertility, mortality, and migration, then population estimates and forecasts need to adjust for climate feedback in population projections. Indisputably, this is the area of new research that directly requires expertise in population science and contribution from demographers.

In Moldova, there has been a long-term decline in the population, mainly due to high levels of emigration. The article presents an analysis of population dynamics in Moldova over the last three decades, and estimates the contributions of fertility, mortality and migration to this process. Using population censuses, data on the population with usual residence, vital statistics and data on Moldovan immigrants from the host countries’ statistical institutes,we estimate population changes between 1991–2021, and present demographic projections up to 2040. The results show that migration outflows account for more than 90% of the depopulation trend, with high levels of premature mortality accelerating the natural decline. The fall in births is associated with a decrease in the reproductive-age population. The total fertility rate has been decreasing gradually, while the cohort fertility rates have not fallen below 1.75 live births per woman. Past migration and low fertility are projected to result in long-term population decline. Demographic ageing is expected to increase. While population decline cannot be stopped, its scale can be limited through reductions in emigration and mortality. This study on population decline in Moldova helps to complete the demographic picture of Europe in the 20th century and into the 21st century.

Irrigation in the Mediterranean is of vital importance for food security, employment and economic development. This study systematically assesses how climate change and increases in atmospheric CO2 concentrations may affect irrigation requirements in the Mediterranean region by 2080–2090. Future demographic change and technological improvements in irrigation systems are taken into account, as is the spread of climate forcing, warming levels and potential realization of the CO2-fertilization effect. Vegetation growth, phenology, agricultural production and irrigation water requirements and withdrawal were simulated with the process-based ecohydrological and agro-ecosystem model LPJmL (Lund–Potsdam–Jena managed Land) after an extensive development that comprised the improved representation of Mediterranean crops. At present the Mediterranean region could save 35 % of water by implementing more efficient irrigation and conveyance systems. Some countries such as Syria, Egypt and Turkey have a higher savings potential than others. Currently some crops, especially sugar cane and agricultural trees, consume on average more irrigation water per hectare than annual crops. Different crops show different magnitudes of changes in net irrigation requirements due to climate change, the increases being most pronounced in agricultural trees. The Mediterranean area as a whole may face an increase in gross irrigation requirements between 4 and 18 % from climate change alone if irrigation systems and conveyance are not improved (4 and 18 % with 2 °C global warming combined with the full CO2-fertilization effect and 5 °C global warming combined with no CO2-fertilization effect, respectively). Population growth increases these numbers to 22 and 74 %, respectively, affecting mainly the southern and eastern Mediterranean. However, improved irrigation technologies and conveyance systems have a large water saving potential, especially in the eastern Mediterranean, and may be able to compensate to some degree for the increases due to climate change and population growth. Both subregions would need around 35 % more water than today if they implement some degree of modernization of irrigation and conveyance systems and benefit from the CO2-fertilization effect. Nevertheless, water scarcity may pose further challenges to the agricultural sector: Algeria, Libya, Israel, Jordan, Lebanon, Syria, Serbia, Morocco, Tunisia and Spain have a high risk of not being able to sustainably meet future irrigation water requirements in some scenarios. The results presented in this study point to the necessity of performing further research on climate-friendly agro-ecosystems in order to assess, on the one hand, their degree of resilience to climate shocks and, on the other hand, their adaptation potential when confronted with higher temperatures and changes in water availability.

We estimate disability prevalence rates and gaps in social conditions in eight Latin America and the Caribbean (LAC) countries and project current and future disability prevalence rates in the region. Using data from representative samples of the population in eight countries, we find that reported disability prevalence varies widely across countries, ranging between 4.5 percent in Trinidad and Tobago (2011) to 24.9 percent in Brazil (2010). Differences in surveying approaches and demographic structures likely explain a part of this variation. We find marked sociodemographic gradients for disability. We also report significant disability gaps: people living with disabilities have lower educational attendance and completion rates and lower employment rates. We use age and sex-specific disability rates from our sample of countries and information on the current and future demographic structures in LAC countries to project disability prevalence for the whole region. We project that the total number of people with disabilities in this region will increase by approximately 60 million between 2020 and 2050. Our projections suggest that countries need to systematically plan and implement inclusion policies to adequately address the growing population of people with disabilities in the years to come.

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.

Population dynamics has been acknowledged as a key concern for projecting future emissions, partly because of the huge uncertainties related to human behaviour. However, the heterogeneous shifts of human behaviour in the process of demographic transition are not well explored when scrutinizing the impacts of population dynamics on carbon emissions. Here, we expand the existing population–economy–environment analytical structure to address the above limitations by representing the trend of demographic transitions to small-family and ageing society. We specifically accommodate for inter- and intra-life-stage variations in time allocation and consumption in the population rather than assuming a representative household, and take a less developed province, Sichuan, in China as the empirical context. Our results show that the demographic shift to small and ageing households will boost energy consumption and carbon emissions, driven by the joint variations in time-use and consumption patterns. Furthermore, biased pictures of changing emissions will emerge if the time effect is disregarded. Future demographic changes will impact on energy use and hence carbon emissions through time-use and consumption pattern shifts. Using representative national time-use data, Yu et al. model scenarios for demographic transitions in China to explore shifts in energy demand as households change in size and age.

Every four years, the National Institute for Public Health and the Environment (RIVM) conducts a public health foresight study to support evidence-based policymaking in the Netherlands. These studies project future health challenges by estimating risk factors, incidence, prevalence, and mortality for a wide range of diseases over the next 25 years. The foresight approach at RIVM uses advanced modeling techniques, including demographic projections, disease models, age-period-cohort models, and risk factor analyses. Both quantitative and qualitative inputs are used, drawing on historical data, surveys, registries, and expert consultations. The analyses also enable projections of disability-adjusted life years (DALYs), calculated by combining Years of Life Lost (YLL) and Years Lived with Disability (YLD). The results highlight future changes in disease burden. Dementia is projected to rise strongly, mainly due to an increase in YLL. Arthrosis will also grow, driven primarily by a rise in YLD. Cardiovascular diseases, although becoming less lethal, will continue to cause a significant burden, with YLD levels remaining high. Producing DALY projections requires key methodological choices. For YLL, remaining life expectancy is based on projected life tables from future all-cause mortality, rather than aspirational life tables. For YLD, it is assumed that the severity distribution of diseases stays constant, even though improvements in detection and treatment could change outcomes. Uncertainty is important and should ideally be addressed through scenario development. Despite limitations, RIVM's foresight studies are essential for proactive public health planning. By identifying future disease burdens and opportunities for action, these projections help policymakers better prepare for emerging challenges, strengthen health resilience, and optimize healthcare systems.

ObjectiveClimate change is expected to increase global temperatures. How temperature-related mortality risk will change is not completely understood, and how future demographic changes will affect temperature-related mortality needs to be clarified. We evaluate temperature-related mortality across Canada until 2099, accounting for age groups and scenarios of population growth.MethodsWe used daily counts of non-accidental mortality for 2000 to 2015 for all 111 health regions across Canada, incorporating in the study both urban and rural areas. A two-part time series analysis was used to estimate associations between mean daily temperatures and mortality. First, current and future daily mean temperature time series simulations were developed from Coupled Model Inter-Comparison Project 6 (CMIP6) climate model ensembles from past and projected climate change scenarios under Shared Socioeconomic Pathways (SSPs). Next, excess mortality due to heat and cold and the net difference were projected to 2099, also accounting for different regional and population aging scenarios.ResultsFor 2000 to 2015, we identified 3,343,311 non-accidental deaths. On average, a net increase of 17.31% (95% eCI: 13.99, 20.62) in temperature-related excess mortality under a higher greenhouse gas emission scenario is expected for Canada in 2090–2099, which represents a greater burden than a scenario that assumed strong levels of greenhouse gas mitigation policies (net increase of 3.29%; 95% eCI: 1.41, 5.17). The highest net increase was observed among people aged 65 and over, and the largest increases in both net and heat- and cold-related mortality were observed in population scenarios that incorporated the highest rates of aging.ConclusionCanada may expect net increases in temperature-related mortality under a higher emissions climate change scenario, compared to one assuming sustainable development. Urgent action is needed to mitigate future climate change impacts.