Scientific achievements

In 2015, the World Population Program (POP) continued its cutting edge research in the areas of multidimensional population dynamics by age, sex, and level of education; redefining age and aging; vulnerability to environmental change; and economic performance and human capital.

Adapted from: © Vítek Prchal | Dreamstime

Adapted from: © Vítek Prchal | Dreamstime

In 2015, POP investigated different aspects of human capital as well as its role in understanding population dynamics.

The model that combines principals of the theory of the demographic metabolism and the tools of multi-dimensional demography was applied to project and analyze the attitudes towards homosexuality in many countries around the world [1].

Pioneering work on redefining population aging to account for its dynamic nature used a “characteristics approach” to measure population aging and the further development of new and more meaningful dependency ratios [2][3][4][5][6][7][8].

Substantial progress was made in further understanding the links between education and disaster and climate change vulnerability and adaptability [9] as well as the role of community participation and strong social networks in preparedness to natural disaster [10].

Researchers working in the Religion, Education, and Demography project have accomplished the first demographic projections of the religiosity using data on age, fertility, mortality, migration, and religious switching for multiple religious groups around the world [11][12][13].

Advancing the theory of demographic metabolism

This theory puts the age-old wisdom that societies change through generational replacement into analytical form. Using the tools of multidimensional demography it presents a formalized model that allows for quantitative forecasts of such societal changes for decades into the future. More

Linking population and climate change

In a new article published in the journal Population Studies [1], Wolfgang Lutz and Erich Striessnig show that population growth and changes in demographic structure are key factors influencing future climate change and people’s ability to adapt. More

Redefining the meaning of age

Life expectancies and levels of health in many developed and developing countries have increased significantly over the past decades, and are expected to continue increasing. In contrast to these profound changes, the concepts that demographers have used to analyze population-level aging have remained largely static. This project proposes alternative dynamic definitions of age. More

More meaningful dependency ratios

If age is not viewed as a static measure, but modified to reflect changing health, life expectancy, and cognitive performance, this has significant consequences for many demographic indicators. Most importantly, the conventional old-age dependency ratio, which assumes that everybody below 65 is productive and everybody above is unproductive, becomes very misleading when used over longer time horizons. More

Vulnerability to natural disasters

Explicitly accounting for population heterogeneity—in particular with respect to level of education—provides an analytical tool for anticipating future vulnerability. Community participation and strong social networks can also aid preparedness to natural disasters in vulnerable regions, shows new research conducted in the south of Thailand. More

Economic performance and human capital

IIASA research has firmly established the fact that improvements in the educational attainment structure of populations are a key driver of economic growth. The new set of global Shared Socioeconomic Pathways scenarios—which define alternative population trajectories by age, sex, and six levels of educational attainment—reflect this, showing that economic growth trajectories follow those of human capital. More

Aging and health

World Population Program (POP) researchers are partners in a new international research project on aging and health, funded by the EU’s Horizon 2020 research and innovation program. The initiative aims to achieve a better understanding of aging by identifying patterns of healthy aging pathways. More

Identifying common sources of population heterogeneity

The World Population Program (POP), with three other IIASA programs—Energy (ENE), Mitigation of Air Pollution and Greenhouse Gases (MAG), and Ecosystems Services and Management (ESM) – continues to implement the crosscutting project “Accounting for socioeconomic heterogeneity in IIASA models” started in 2014. More

The future of world religions

The religious profile of the world is rapidly changing, driven primarily by differences in fertility rates and the size of youth populations among the world’s major religions, as well as by people switching faiths. New research provides insights into future trajectories of religious change in the world. More

Global human capital data sheet 2015

The Global Human Capital Data Sheet 2015, produced by the World Population Program (POP), presents new population projections by age, sex, and level of educational attainment for all countries in the world with projections to 2060. Alongside this, a visualization tool allows exploration of the projections, focusing on progress in female education. More


[1] Striessnig E and Lutz W. Demographic Metabolism at Work. Submitted to Demography.

[2] Sanderson WC and Scherbov S (2015). Faster Increases in Human Life Expectancy Could Lead to Slower Population Aging. PLoS ONE 10(4): e0121922.

[3] Sanderson, WC and Scherbov S (2015). A new perspective on patterns of aging in Europe by education and gender. Journal of Population Ageing, 1–19. doi:10.1007/s12062-015-9125-z

[4] Sanderson WC and Scherbov S (2015). An easily understood and intergenerationally equitable normal pension age. In The Future of Welfare in a Global Europe ed. Marin B pp. 193-220, Ashgate Publishing, Ltd UK.

[5] Sanderson WC and Scherbov S (2015). Are we overly dependent on conventional dependency ratios? Population and Development Review 41(4): 687–708.

[6] Gietel-Basten S, Scherbov S, and Sanderson W (2015). Remeasuring ageing in Southeast Asia. Asian Population Studies 11(2): 191–210.

[7] Bordone V, Scherbov S, and Steiber N (2015). Smarter every day: The deceleration of population ageing in terms of cognition. Intelligence 52: 90–96.

[8] Steiber N (2015). Population aging at cross-roads: Diverging secular trends in average cognitive functioning and physical health in the older population of Germany. PLoS ONE 10(8): e0136583.

[9] Lutz W and Striessnig E (2015). Demographic aspects of climate change mitigation and adaptation. Population Studies 69(sup1): S69–S76.

[10] Witvorapong N, Muttarak R, and Pothisiri W (2015). Social Participation and Disaster Risk Reduction Behaviors in Tsunami Prone Areas. PLOS ONE. DOI:10.1371/journal.pone.0130862

[11] Stonawski M, Skirbekk V, Hackett C, Potančoková M, Connor P, and Grim B (2015). Global population projections by religion: 2010-2050. Yearbook of International Religious Demography 2015. pp 99-116. 

[12] Hackett C, Stonawski M, Potancokova M, Grim B, and Skirbekk V (2015). The future size of religiously affiliated and unaffiliated populations. Demographic Research, 32(1):829-842.

[13] Pew Research Center (2015). The Future of World Religions: Population Growth Projections, 2010-2050.

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Last edited: 25 February 2016


Wolfgang Lutz

Program Director

World Population

T +43(0) 2236 807 294

International Institute for Applied Systems Analysis (IIASA)
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Phone: (+43 2236) 807 0 Fax:(+43 2236) 71 313