Demographic scenarios by age,sex and education corresponding to the SSP narratives

In this paper, we translate the five narratives as defined by the Shared Socioeconomic Pathways (SSPs) research community into five alternative demographic scenarios using projections by age, sex and level of education for 171 countries up to 2100. The scenarios represent a significant step beyond past population scenarios used in the Intergovernmental Panel for Climate Change context, which considered only population size. The definitions of the medium assumptions about future fertility, mortality, migration and education trends are taken from a major new projections effort by the Wittgenstein Centre for Demography and Global Human Capital, while the assumptions for all the other scenarios were defined in interactions with other groups in the SSP community. Since a full data base with all country-specific results is available online, this paper can only highlight selected results.     

Enhancing engagement between the population,environment, and climate research communities: the shared socio-economic pathway process

Demographers have much to contribute to climate change science. This paper describes a new framework being developed by the climate research community that holds potential as an organizing tool for population–climate scholarship, as well as being useful for identifying demographic research gaps within the climate change field. The shared socio-economic pathways (SSPs) represent plausible alternative trends in the evolution of social and natural systems over the twenty-first century at the scale of the world and large regions. The SSPs can help identify population–environment research gaps by illuminating areas of intersection that will shape climate futures but require deeper scientific understanding—the association between urbanization and energy consumption is an example. Also, to vastly enhance the policy relevance of local case studies, the parameters outlined within the SSPs can offer a basic level of harmonization to facilitate generalization. In this way, the SSP framework can increase the relevance and accessibility of population research and, therefore, offer a mechanism through which demographic science can truly offer policy impact.     

Understanding Global Demographic Convergence since 1950

Is the world converging to a single demographic regime? Or are groups of countries following distinct paths through the process of demographic transition? The answers to these questions are pivotal to our understanding of the nature and mechanisms of population change. They are also key elements for deriving the assumptions that should underlie population projections. There has been considerable interest in global demographic convergence during the last decade, with most work drawing on statistical methods that are widely used in economics. This article takes a different approach to most of the existing literature, examining the fertility and mortality trajectories over time that various appropriately defned world regions have followed. The data suggest that five distinct regional histories can be traced in mortality, and three in fertility, and that global convergence has moved more rapidly and unambiguously in fertility than in mortality.     

Population Scenarios Based on Probabilistic Projections: An Application for the Millennium Ecosystem Assessment

Probabilistic population forecasts offer a number of advantages to users. However, in some cases population is one component of a larger analysis that may take a different approach to uncertainty. For example, integrated assessments of environmental issues such as climate change or ecosystem degradation have typically used a small number of alternative scenarios to explore uncertainty in future environmental outcomes. In such cases, population projections that are provided only as probability distributions are difficult to use. I present a method of employing probabilistic population projections to derive individual, deterministic projections that can be used within scenarios for integrated assessments. The principal advantages of this approach are that (1) it provides a less ad hoc way of defining deterministic projections intended to be consistent with more comprehensive scenarios that describe, among other things, future socio-economic developments; (2) it provides more flexibility in specifying input assumptions for deterministic projections as compared to choosing off-the-shelf projections, allowing population assumptions to be tailored to the scenario; and (3) it provides a quantitative assessment of the uncertainty associated with any given deterministic projection. I describe the application of the method to the development of population projections used in integrated scenarios for the Millennium Ecosystem Assessment, an international scientific effort to assess the current conditions of and future outlook for global ecosystem goods and services. Results show that the MA scenarios are each consistent with a relatively wide range of demographic outcomes. For some scenarios, ranges of plausible outcomes in some regions overlap substantially, indicating that particular population projections could be consistent with more than one scenario. In other cases, uncertainty ranges for different scenarios are distinct, indicating that a projection consistent with one scenario is unlikely to be also consistent with another. Comparing variances of the conditional projections also provides insight into how much different storylines constrain future demographic developments. The development of the MA projections points to important areas of future research on correlations among demographic rates and on uncertainty across scales. It also serves as an illustration of how probabilistic and alternative scenario-based approaches to uncertainty can be combined within a single integrated analysis.This revised version was published online in April 2005 with corrections to figures 1-3.     

Demographic Changes in North Korea: 1993–2008

Given the scarcity of population data, few demographic analyses have been conducted on population trends in North Korea. Using the 1993 and 2008 population and housing census data, we prospectively reconstruct population change in the country during the 15 intercensal years. Reconstruction of the population trends of North Korea enables us to assess the consistency of the available demographic evidence and to assess the demographic impact of the famine in the 1990s. According to the results of the population reconstruction and our counterfactual population projections, the famine caused between 240,000 and 420,000 total excess deaths—lower than the previous estimate of 600,000–1 million; and the human costs of the deteriorating living conditions between 1993 and 2008 may be estimated as 600,000 to 850,000 total excess deaths attributable to economic decline in the post‐Cold war era. The reconstructed population trends mirror the continuing deterioration of the living conditions in North Korea since the early 1990s.     

The United Nations on World Population in 2300

The Population Division of the United Nations biennially issues detailed population estimates and projections covering the period 1950–2050. The most recent revision of these estimates and projections, the 2002 assessment, was released in February 2003. At irregular intervals, the Population Division also publishes long‐range projections. The most recent of these, covering the period up to 2150, was issued in 2000, based on the 1998 assessment. On 9 December 2003, the Population Division released the preliminary report on a new set of long‐range projections, dovetailing with the 2002 assessment, that extend over a much longer time span: up to 2300 ( http://www.un.org/esa/population/publications/longrange2/longrange2.htm ). Unlike previous long‐range projections, which, apart from China and In‐dia, were prepared for large regional groupings only, the new projections are elaborated separately for 192 countries. Given the enormous uncertainties of the character of demographic trends over such an extended period, the information content of these projections is somewhat elusive. However, they are expected to be used to provide the demographic input for long‐range models of global climate change. Long‐range population projections also serve to demonstrate the unsustainability of certain seemingly plausible assumptions as to the future course of particular demographic parameters. In the present case, for example, the high‐fertility projection, reflecting a sustained total fertility rate at the relatively modest level of 2.35, by 2300 would yield a population of some 32 billion in the countries now classified as less developed. Or, in a yet more extreme exercise 0/reductio ad absurdum, maintaining constant fertility at present rates would result in a population size of some 120 trillion in the countries now classified as least developed. Apart from the “high fertility” and “constant fertility” models just cited, the projections are calculated for three additional instructive variants: “low fertility,”“medium fertility,” and “zero growth.” Underlying each of the five variants is a single assumption on mortality change: expectation of life at birth creeping up, country‐by‐country, to a 2300 level ranging between 88 and 106 years. International migration is set at zero throughout the period 2050‐2300 in each variant. Thus the projections are unabashedly stylized and surprise‐free, providing a simple demonstration of the consequences, in terms of population size and age structure, of clearly stated assumptions on the future course of demographic variables. Reproduced below is the Executive Summary of the preliminary report on the UN long‐range projections presented to a UN technical working group on long‐range projections at its December 2003 meeting in New York and slightly revised afterward. A full final report on this topic by the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat will be published later in 2004.     

Population Projections and Demographic Knowledge in France and Great Britain in the Postwar Period

This study examines how official national population projections—a key mechanism for the production and dissemination of demographic knowledge—contributed to differing interpretations of population and fertility trends in France and Great Britain in the decades following World War II, despite these countries' similar fertility rates during most of this period. Projections presented different visions of the demographic future in the two countries. In France, publication of multiple variants emphasized future contingency, with low variants illustrating future population decline due to prolonged below‐replacement fertility. In Britain, publication of a single variant, assuming near‐replacement‐level fertility rates, projected moderate growth. National population projections thus created divergent representations of the two countries' demographic futures: an ever‐present threat of population decline in France, and a reassuring image of stability in Britain. Two principal mechanisms that contributed to cross‐national differences in population projections—national demographic history and institutional configurations—are discussed.     

Replacement Migration: A Questionable Tactic for Delaying the Inevitable Effects of Fertility Transition

This article critiques a recent U.N. Population Division report, Replacement Migration: Is it a Solution to Declining and Ageing Populations? The report explores the use of increased immigration to bolster future population size and change age distribution patterns in a group of developed countries. Fertility rate declines and lengthening life expectancies associated with demographic transition inevitably yield an aging population and a falling potential support ratio (PSR), a situation which some demographers and economists view with alarm. As the U.N. report itself suggests, replacement migration can only temporarily delay population aging and decline. These issues are ultimately better addressed through changes in retirement policy. Population projections should be used only with great caution in designing long-term demographic policy. In particular, some assumptions used to make the U.N. projections are questionable, and even minor changes in those assumptions would yield substantially different policy conclusions. Replacement migration also raises difficult environmental questions by moving large numbers of people from low to high per-capita consumption nations. Modest population decline, particularly in more developed countries, may have significant local and global environmental and climate policy benefits.

     

How do Recent Population Trends Matter to Climate Change?

Although integrated assessment models (IAM) of the Intergovernmental Panel on Climate Change (IPCC) consider population as one of the root causes of greenhouse gas emissions, how population dynamics affect climate change is still under debate. Population is rarely mentioned in policy debates on climate change. Studies in the past decade have added significantly to understanding the mechanisms and complexity of population and climate interactions. In addition to the growth of total population size, research shows that changes in population composition (i.e. age, urban–rural residence, and household structure) generate substantial effects on the climate system. Moreover, studies by the impact, vulnerability and adaptation (IAV) community also reveal that population dynamics are critical in the near term for building climate change resilience and within adaptation strategies. This paper explores how global population dynamics affect carbon emissions and climate systems, how recent demographic trends matter to worldwide efforts to adapt to climate change, and how population policies could make differences for climate change mitigation and adaptation.     

U.S. Family Household Momentum and Dynamics: An Extension and Application of the ProFamy Method

The classic headship-rate method for demographic projections of households is not linked to demographic rates, projects a few household types without size, and does not deal with household members other than heads. By comparison, the ProFamy method uses demographic rates as input and projects more detailed household types, sizes, and living arrangements for all members of the population. Tests of projections from 1990 to 2000 using ProFamy and based on observed U.S. demographic rates before 1991 show that discrepancies between our projections and census observations in 2000 are reasonably small, validating the new method. Using data from national surveys and vital statistics, census microfiles, and the ProFamy method, we prepare projections of U.S. households from 2000 to 2050. Medium projections as well as projections based on smaller and larger family scenarios with corresponding combinations of assumptions of marriage/union formation and dissolution, fertility, mortality, and international migration are performed to analyze future trends of U.S. households and their possible higher and lower bounds, as well as enormous racial differentials. To our knowledge, the household projections reported in this article are the first to have found empirical evidence of family household momentum and to have provided informative low and high bounds of various indices of projected future households and living arrangements distributions based on possible changes in demographic parameters.     

Can Knowledge Improve Population Forecasts at Subcounty Levels?

Recent developments in urban and regional planning require more accurate population forecasts at subcounty levels, as well as a consideration of interactions among population growth, traffic flow, land use, and environmental impacts. However, the extrapolation methods, currently the most often used demographic forecasting techniques for subcounty areas, cannot meet the demand. This study tests a knowledge-based regression approach, which has been successfully used for forecasts at the national level, for subcounty population forecasting. In particular, this study applies four regression models that incorporate demographic characteristics, socioeconomic conditions, transportation accessibility, natural amenities, and land development to examine the population change since 1970 and to prepare the 1990-based forecast of year 2000 population at the minor civil division level in Wisconsin. The findings indicate that this approach does not outperform the extrapolation projections. Although the regression methods produce more precise projections, the least biased projections are often generated by one of the extrapolation techniques. The performance of the knowledge-based regression methods is discounted at subcounty levels by temporal instability and the scale effect. The regression coefficients exhibit a statistically significant level of temporal instability across the estimation and projection periods and tend to change more rapidly at finer geographic scales.     

Aids and population growth in sub-Saharan Africa: Assessing the sensitivity of projections

Despite different models to project the course of the AIDS pandemic and a scarcity of data to provide standard input parameters for those models, a limited consensus emerges from distinct sets of population projections. In sub-Saharan Africa, population growth rates are projected to remain positive in spite of the pandemic over the next few decades. To investigate this conclusion, alternative projections of an HIV/AIDS epidemic and its related mortality are first produced from different sets of input parameters and assumptions. Their incorporation into the population projections of a fast-growing country illustrates the robustness of projected population growth rates under very different scenarios of the future epidemic but with the common assumption that it will not affect the mortality of the uninfected population, fertility nor migration. This paper then shows that the projected growth rates are much less robust when interactions between the epidemic and the demographic regime are allowed and identifies several potential mechanisms for such interactions. In particular, it suggests that improving our confidence in the medium-term projections of the demographic impact of AIDS in the region requires less a refinement of the projections of the epidemic than a better understanding of its impact on the timing of the postulated fertility decline.     

Dudley Kirk on Population Changes and Prospective Power Relations after World War II: A View from 1943

The theory of demographic transition in its best‐known modern formulation was developed in the early 1940s by a small group of researchers associated with Princeton University's Office of Population Research, under the leadership of Frank W. Notestein. A notable early adumbration of the theory in print—in fact preceding the most often cited contemporaneous articles by Notestein and by Kingsley Davis—was by Dudley Kirk, one of the Princeton demographers, in an article titled “Population changes and the postwar world,” originally presented by its author on 4 December 1943 at the 38th Annual Meeting of the American Sociological Society, held in New York. It is reproduced below in full from the February 1944 issue of American Sociological Review (Vol. 9, no. 1, pp. 28–35). In the article Kirk, then 30 years old, briefly discusses essential elements of the concept of the demographic transition. He characterizes trends in birth and death rates as closely linked to developmental changes: to the transition “from a peasant, self‐sufficient society to an urban, industrial society.” He sees the countries of the world as arranged on a “single continuum of development” and, correspondingly, on a continuum of demographic configurations. These countries, he suggests, may be divided into three broad groups: the first, with high mortality and high fertility, possessing great potential population growth; the second, “caught up in the tide of industrialization and urbanization,” hence exhibiting birth and death rates that are both declining but in a pattern that generates rapid population growth; and a third, with low fertility and low mortality, pointing toward the prospect of eventual depopulation. He describes the temporal and geographic process of material progress and demographic change as one of cultural and technological diffusion emanating from the West. But Kirk's main interest in this article is the effects of the patterns generated by economic change and the ensuing demographic transition on shifts in relative power—military and economic—within the system of nations, both historically and in the then dawning postcolonial era. On the latter score, even if occasionally colored by judgments reflecting perspectives unsurprising in 1943, such as in his assessment of the economic potential of the Soviet Union, Kirk's probing of the likely consequences of evolving trends in power relationships as shaped by shifting economic and demographic weights—issues now largely neglected in population studies—is often penetrating and remarkably prescient. His views on the implication of these trends for the desirable American stance toward the economic and demographic modernization of less developed countries—friendly assistance resulting in rapid expansion of markets, and trade speeding a social evolution that also brings about slower population growth—represent what became an influential strand in postwar US foreign policy. Dudley Kirk was born 6 October 1913 in Rochester, New York, but grew up in California. After graduating from Pomona College, he received an M.A. in international relations from the Fletcher School of Law and Diplomacy of Tufts University in 1935 and a Ph.D. in sociology from Harvard in 1946. He was associated with Princeton's OPR between 1939 and 1947, where he published his influential monograph Europe's Population in the Interwar Years (1946) and, with Frank Notestein and others, coauthored the book The Future Population of Europe and the Soviet Union (1944). From 1947 to 1954 he was demographer in the Office of Intelligence Research of the US State Department, the first person having that title in the federal government. From 1954 to 1967 he was director of the Demographic Division of the Population Council in New York, and from 1967 until his retirement in 1979 he was professor of population studies at Stanford University. In 1959–60 he was president of the Population Association of America. Dudley Kirk died 14 March 2000 in San Jose, California.     

Population,projections, and policy: A cautionary perspective

Population projections depend on censuses, vital statistics and sample surveys, all of which have deficiencies that are most marked in the less developed countries (LDCs). Long-range projections by international agencies have recently undergone major revisions, while forecasts of the U.S. population have changed drastically over the past four years. The United Nations typically prepares “high,” “medium” and “low” projections. Even the high projection contains optimistic assumptions about fertility decline, while assumptions of constant or increasing fertility receive no serious attention. The paper suggests that high and constant fertility projections should receive more attention from policy makers, with medium estimates treated more as targets achievable only through considerable programmatic effort. At the same time, economic and social plans should be laid for dealing with the population sizes implied by the “high” variants.     

Cuba: the demography of revolution

Cuba's post-revolution demographic trends, especially in regard to fertility and emigration, and the causes and consequences of these trends, were examined using available statistical data. The authors maintain that both fertility and emigration trends were highly infuenced by economic factors. The trends are described in the context of the social and economic changes instituted by the revolutionary government. Government policies were aimed at 1) eradicating inequalities in housing, income, education, and health; 2) improving the status of women; and 3) upgrading the living standards of the rural population. Government policies did alleviate many social problems and greatly improved the health and educational status of the population; however, these policies had a marked adverse effect on economic performance. The demographic transition began in Cuba earlier than in most other developing countries and it began long before the 1959 revolution. These earlier changes must be taken into account when assessing the impact of post-revolution policies on demographic trends. Cuba's birthrate declined from 26-14.8/1000 population between 1959-1979 and the total fertility rate declined from 3.7-1.9 between 1970-1978; however, during the 1960s there was a baby boom and the birth rate for 1963 exceeded 35/1000 population. The baby boom was largely a response to the temporary improvement in economic conditions which occurred shortly after the revolution. The decline in fertility during the 1970s was due in part to the increased availability of abortion and contraceptive services and to a decline in the marriage rate; however, Cuba's deteriorating economy was also a major contributing factor. The baby boom of the 1960s is negativley affecting the current economy of the country. Individuals born during the baby boom are entering adulthood and are contributing toward Cuba's current unemployment problems. Prior to the revolution, Cuba experienced a high rate of in-migration. Immediately after the revolution this pattern was reversed and between 1959-1980 more than 800,000 Cubans emigrated. Most of these emigrants went to the U.S. A large proportion of the earlier emigrants were members of the upper and middle socioeconomic classes. Recent emigrants were more evenly representative of all segments of Cuba's population. The socioeconomic characteristics of the emigrants are described and their adjustment in the U.S. is discussed. Tables provide statistical data on Cuba's demographic trends.     

Masculinity,Money, and the Postponement of Parenthood in Nigeria

In southeastern Nigeria, several interconnected processes of social change are combining to delay parenthood. Most of the demographic and social sciences literature examining the postponement of parenthood has paid primary attention to women. To address this gap, this article foregrounds the changing social landscape of masculinity as a significant context within which to situate these demographic changes. At the core of Nigerian men's perceptions, decisions, and behaviors with regard to delaying fatherhood is a fundamental contradiction, one that seems to be common in many settings—at least many African settings—of contemporary demographic transition. The contradiction is that while the postponement of parenthood is associated historically with positive social and economic indicators, when Nigerian men articulate their rationales for delaying fatherhood (and marriage) they commonly describe feelings of uncertainty connected to a sense of struggle and deprivation. This article connects men's anxieties about—and delays embarking on—marriage and parenthood to their experiences of economic uncertainty, and specifically to the perceived need for money as the foundation for successful reproduction.     

Women,Demography, and Politics: How Lower Fertility Rates Lead to Democracy

Where connections between demography and politics are examined in the literature, it is largely in the context of the effects of male aspects of demography on phenomena such as political violence. This project aims to place the study of demographic variables’ influence on politics, particularly on democracy, squarely within the scope of political and social sciences, and to focus on the effects of woman-related demographics—namely, fertility rate. I test the hypothesis that demographic variables—female-related predictors, in particular—have an independent effect on political structure. Comparing countries over time, this study finds a growth in democracy when fertility rates decline. In the theoretical framework developed, it is family structure as well as the economic and political status of women that account for this change at the macro and micro levels. Findings based on data for more than 140 countries over three decades are robust when controlling not only for alternative effects but also for reverse causality and data limitations.     

Impacts of population change on vulnerability and the capacity to adapt to climate change and variability: a typology based on lessons from “a hard country”

This article describes and analyzes the impacts of population and demographic change on the vulnerability of communities to climate change and variability. It begins with a review of existing literature on the effects of population change on anthropogenic greenhouse gas emissions, the exposure of settlements to climate risks, and on the capacity to adapt to climate change. The article explores the relationship between population change and adaptive capacity through detailed examination of empirical findings from a study of small communities in eastern Ontario, Canada currently experiencing a combination of changes in local climatic conditions and rapid demographic change caused by in-migration of urban retirees and out-migration of young, educated people. The combination of changing demographic and climatic patterns has placed increased stress on local social networks that have long been critical to climate adaptation in that region. The case study and literature review are used to create a general typology of the relationship between population change and vulnerability that may be used as a framework for future research in this field.     

Demographic aspects of climate change mitigation and adaptation

This paper addresses the contribution of changes in population size and structures to greenhouse gas emissions and to the capacity to adapt to climate change. The paper goes beyond the conventional focus on the changing composition by age and sex. It does so by addressing explicitly the changing composition of the population by level of educational attainment, taking into account new evidence about the effect of educational attainment in reducing significantly the vulnerability of populations to climatic challenges. This evidence, which has inspired a new generation of socio-economic climate change scenarios, is summarized. While the earlier IPCC-SRES (Intergovernmental Panel on Climate Change—Special Report on Emissions Scenarios) scenarios only included alternative trajectories for total population size (treating population essentially as a scaling parameter), the Shared Socio-economic Pathways (SSPs) in the new scenarios were designed to capture the socio-economic challenges to climate change mitigation and adaptation, and include full age, sex, and education details for all countries.     

中国人口的迁移转变——基于迁移率的考察

经典人口转变理论侧重死亡和生育转变过程的测量、描述和解释,地理学家将迁移转变纳入人口转变框架,以完善人口转变理论。不过与死亡和生育转变研究不同,中国的迁移研究侧重基于对迁移流动人口规模和结构的考察分析,少有采用人口学意义上的迁移率指标的研究。文章利用2010—2015年历次中国综合社会调查的合并数据,通过人口学方法和泊松回归模型,计算和分析了1950—2015年中国人口迁移率趋势及社会经济差异。中国的迁移转变在宏观趋势上与中国的政治经济变迁高度一致。与死亡和生育转变相比,其波折性更强,说明更易受到经济社会政策变化的冲击。同时也观察到逢“0”和逢“5”年份的申报偏好。另外,迁移的社会经济差异明显。男性迁移率高于女性,但是两性差异在不断缩小;乡城迁移和未婚迁移大幅度增长;而越来越多受教育程度较高人群加入迁移,使得受教育程度越高的人群具有越高的迁移率。可以认为基于迁移率的考察揭示了中国迁移转变更具体生动的过程。