Internal consistency of demographic assumptions in the shared socioeconomic pathways

A new set of alternative socioeconomic scenarios for climate change researches—the shared socioeconomic pathways (SSPs)—includes for the first time a more comprehensive set of demographic conditions on population, urbanization, and education as the central scenario elements, along with other aspects of society, in order to facilitate better analyses of challenges to climate change mitigation and adaptation. However, it also raises a new question about the internal consistency of assumptions on different demographic and economic trends under each SSP. This paper examines whether the interactions between the demographic and economic factors implied by the assumptions in the SSP projections are consistent with the research literature, and whether they are consistently represented in the projection results. Our analysis shows that the interactions implied by the demographic assumptions in the SSPs are generally consistent with findings from the literature, and the majority of the assumed relationships are also evident in the projected trends. It also reveals some inconsistency issues, resulting mainly from the use of inconsistent definitions of regions and limitations in our understanding of future changes in the patterns of interactions at different stages of socioeconomic development. Finally, we offer recommendations on how to improve demographic assumptions in the extended SSPs, and how to use the projections of SSP central elements in climate change research.     

Climate change and population migration in Brazil’s Northeast: scenarios for 2025–2050

This research contributes to an understanding of the relationship between climate change, economic impacts and migration. We model the long-term relationship (up to 45 years of projection) between demographic dynamics—particularly migration—driven by changes in the performance of the economy due to climate changes in the Northeast region of Brazil. The region is of particular relevance to the study of climate change impacts given its large human population (28% of Brazil’s population) and high levels of impoverishment, having an extensive semi-dry area which will be severely impacted by growing temperatures. Ultimately, the integrated model generates state- and municipal-level migration scenarios based on climate change impacts on the primary economic sectors and their articulations with other sectors. Results suggest that the predicted climate changes will impact severely the agriculture sector in the region, acting as a potential migration push factor to other regions in the country. Finally, we discuss how the increased vulnerability of some groups, particularly migrants, can be factored into Brazilian public policy and planning.     

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.     

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.     

Science,Modernity, and the Making of China's One‐Child Policy

China's one‐child‐per‐couple policy represents an extraordinary attempt to engineer national wealth, power, and global standing by drastically braking population growth. Despite the policy's external notoriety and internal might, its origins remain obscure. In the absence of scholarly research on this question, public discourse in the United States has been shaped by media representations portraying the policy as the product of a repressive communist regime. This article shows that the core ideas underlying the one‐child policy came instead from Western science, in particular from the Club of Rome's world‐in‐crisis work of the early 1970s. Drawing on research in science studies, the article analyzes the two notions lying at the policy's core—that China faced a virtual “population crisis” and that the one‐child policy was “the only solution” to it—as human constructs forged by specific groups of scientists working in particular, highly consequential contexts. It documents how the fundamentally political process of constituting population as an object of science and governance was then depoliticized by scientizing rhetorics that presented China's population crisis and its only solution as numerically describable, objective facts. By probing the human and historical character of population research, this article underscores the complexity of demographic knowledge‐making and the power of scientific practices in helping constitute demographic reality itself.     

Policy review: thoughts on addressing population and climate change in a just and ethical manner

Many believe that linking population growth to the issue of climate change will help to place family planning back into the political realm as an urgent matter of national and environmental security. Others worry, however, that focusing on the environmental impacts of demographic change places at risk the hard-fought and long-developed global consensus that individual rights and empowerment are what matters most in fostering sustainable development and stabilizing population growth. This paper focuses on United States population policy. It presents a brief historical background and summarizes the state of scientific evidence regarding the impacts of population growth on climate change. It then analyzes some of the underlying ethical issues involved in advancing an advocacy argument around increasing family planning as a way to slow population growth and mitigating climate change. Finally, it recommends a way in which advocates can frame the connections between population growth and climate change in a just and ethical manner.     

A spatial analysis of population dynamics and climate change in Africa: potential vulnerability hot spots emerge where precipitation declines and demographic pressures coincide

We present an integrative measure of exposure and sensitivity components of vulnerability to climatic and demographic change for the African continent in order to identify “hot spots” of high potential population vulnerability. Getis-Ord Gi* spatial clustering analyses reveal statistically significant locations of spatio-temporal precipitation decline coinciding with high population density and increase. Statistically significant areas are evident, particularly across central, southern, and eastern Africa. The highly populated Lake Victoria basin emerges as a particularly salient hot spot. People located in the regions highlighted in this analysis suffer exceptionally high exposure to negative climate change impacts (as populations increase on lands with decreasing rainfall). Results may help inform further hot spot mapping and related research on demographic vulnerabilities to climate change. Results may also inform more suitable geographical targeting of policy interventions across the continent.     

Intergenerational transfers in US county-level CO2 emissions, 2007

Research has shown that increases in carbon emissions and resulting climate change are not driven by population size alone, but also associated with industrialization, urbanization, and economic development. Further, industrialization and development may, in part, be driven by changing demographic structure, and in particular the process of population aging. Fluctuations in age composition shape aggregate production and consumption. Viewed through this lens, the carbon dioxide emissions of an analytical unit (county, province, state, nation) can be considered a product of its age composition. This analysis tests several demographic theories of age-specific production and consumption on US county-level carbon dioxide emissions. Using a modified STIRPAT framework, econometric estimates identify a positive correlation between county-level labor force participation and total carbon dioxide emissions. These effects are a result of general economic activity as opposed to growth only in energy intensive industrial sectors, a relationship that is widely hypothesized but under-developed in carbon emission estimates. In addition, results show larger households are associated with lower aggregate emissions, confirming the hypothesis that areas of declining household size will experience higher future emissions. In general, this research demonstrates the importance of adding nuance to emission estimates by integrating demographic dimensions beyond population size and growth.     

‘Closing the Gap’ in Indigenous life expectancies: what if we succeed?

In 2007–2008 the Council of Australian Governments agreed to six ambitious targets for addressing longstanding disparities between Indigenous and other Australians in health, education and employment outcomes. The ‘National Integrated Strategy for Closing the Gap on Indigenous Disadvantage’ (colloquially ‘Closing the Gap’) includes the goal of eliminating life expectancy gaps within a generation. This policy says nothing about what changes in the demographic structure of the population might be expected should there be even partial success towards this ambitious target. Information is required to analyse age and sex shifts for their effects on service demand and provision. In this study we apply cohort component projections modelling to the Northern Territory, the Australian jurisdiction with the largest Indigenous component in its population and the largest life expectancy gaps, to assess the demographic effects of closing the gap within a generation. Three scenarios are modelled: (1) No changes to Indigenous life expectancies from those estimated in 2010; (2) Complete success in closing the gap within a generation; and (3) A continuation of current forecasts about how Indigenous life expectancies will change into the future. Although closing the gap would only produce a small increase in the size of the next generation’s Indigenous population, over and above that projected with lower life expectancy scenarios, it would result in substantial changes in age compositions, with associated shifts in various demographic indices. These are pertinent to the planning and funding of core services into the future.     

The fall in household size and the rise of the primary individual in the United States

The long-term fall in household size in the United States is discussed within the framework of the aging of the population, continuing as the effects of fertility and mortality decline accumulate. Using distributions of households by size from U.S. census data 1790–1970 and a components of change analysis on primary individuals for 1950–1974, household changes are related to demographic change for the periods 1790–1900, 1900–1950, and 1950–1974. Fertility and mortality declines have unambiguous impact on household size until the increases in primary individuals begin. But these, too, have a theoretically interesting, if indirect relationship to population structure.     

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.     

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.     

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.

     

Australia’s population growth,composition and distribution: Emerging research needs

In 1993 the charter of the Bureau of Immigration Research (BIR) was widened to encompass other areas of population and its name changed to the Bureau of Immigration and Population Research (BIPR). The paper argues that for too long population policy and policy-related research in Australia has been synonymous with immigration policy and research and that this change presents an opportunity to redress this imbalance and broaden the range of areas across which government and private sector activity in Australia can be assisted through knowledge of population dynamics. It is essential, however, that the BIPR broaden the scope of its activity and the present paper presents a research agenda which encompasses a range of population issues of relevance to contemporary private and public sector activity. A version of this paper was presented to a seminar organized by the Centre for Immigration and Multicultural Studies and the Demography Program of the Australian National University for the Bureau of Immigration and Population Research in Canberra, 20 August 1993.     

Controlling population growth in Sri Lanka: perceptions,policies and strategies

Sri Lanka has been an oft-cited example in the demographic literature of developing countries over the past 4 decades. Despite its low level of per capita income, Sri Lanka has managed to achieve the lowest level of fertility in South Asia. Sri Lanka's population policies, especially with regard to fertility, have been rated as strong by some writers. The evolution of policies on population growth in Sri Lanka is described in the following sections: the problem of population growth, strategies for controlling population growth, the period of indirect government participation from 1948 to 1965, policy change during 1965-77, 1977 as the beginning of a new era of increasing government commitment to domestic population polices, and strategy changes from 1989 onwards. During this current, most recent, phase of population policy in Sri Lanka, the government has focused upon satisfying the demand for various family planning methods, demand which has been created by a well-promoted fertility control program during the preceding phases of policy implementation. Greater emphasis is simultaneously being given to improving reproductive health.     

Inter- and transdisciplinary approaches to population–environment research for sustainability aims: a review and appraisal

The causes and consequences of demographic changes for the environment, and the possible ways of influencing population dynamics to achieve ‘sustainability’, have been the subject of many debates in science and policy in recent decades. However, the body of knowledge concerning relationships between population dynamics and sustainability is quite fragmented, dispersed over many disciplines, and encompasses diverse theories, paradigms and methodologies. This paper reviews four selected frameworks: linear, multiplicative, mediated, and system-theoretical approaches and perspectives. We represent how population–environment relationships are conceptualized, provide examples of research questions and accepted approaches, and critically assess their utility for different sorts of research for sustainable development. We note the growing recognition of the value of embracing complexity in population–environment research, and how this is consistent with normative aims of development.     

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.     

Population policy: Personal notes

Abstract These are the population years: throughout the world, in both developing and developed countries, there has been a growing debate on population policy. In this paper population policy refers to governmental actions that are designed to alter population events, or that do alter them. The concern with policy seems to center in the relationships between four demographic variables (size, rates, distribution, composition) and four 'quality of life' categories as both determinants and consequences (comprehended here as economic, political, ecological/environmental, social). As to policy means, they can be seen as being five in number (information, voluntary programmes, change in social institutions, incentives and disincentives, and coercion) with the potential of affecting the three factors of fertility, mortality, and migration. The relationships and effects of these conceptual cross tabulations are illustrated.