Climate research needs a greater focus on human populations

The way in which climate change will affect future populations will depend largely on people’s capacity to adapt to changing conditions. According to IIASA researchers, such characteristics can be forecast in the long term using well-established demographic methods.

Climate research has provided a range of scenarios showing how climate change will affect global temperatures, water resources, agriculture, and many other areas. Yet it remains unclear how all these potential changes could affect future human wellbeing. In particular, the population of the future – in its composition, distribution, and characteristics – will not be the same as the population observed today. That means that assessing likely impacts by relating the climate change projected for the future to today’s societal capabilities can be misleading. In order to understand the impacts of climate change on human beings, climate change research needs to explicitly consider forecasting human populations’ capacities to adapt to a changing climate.

The demographic tools to do this are already available and well established. Global IIASA population and human capital scenarios up to the year 2100 include not just numbers of people, but also their distribution by age, sex, and education level. These scenarios form the human core of the Shared Socioeconomic Pathways (SSPs) that are widely used in research related to climate change.

In an article based on a growing body of research from IIASA and the Vienna Institute of Demography [1], which was published in the journal Nature Climate Change [2], IIASA researchers discuss a conceptual model that can account for the changing characteristics of populations through the replacement of generations, called “demographic metabolism.”

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The concept of demographic metabolism can be described as the process whereby individuals in a population are constantly replaced, just like cells turn over in a body. People of today differ in many ways from their parents and grandparents, and the same will hold true for future generations. They differ in education levels, in health, environmental awareness, and many other factors—and what the research has shown is that these factors directly affect a population’s vulnerability to natural disasters or changes in the environment.

The researchers explain that some characteristics that people acquire early in life, like education, remain with them throughout their lives. Research by the IIASA World Population Program has shown that education in particular influences how vulnerable people are to natural disasters like floods and storms, which are expected to increase as a result of climate change. With more educated younger generations replacing the older ones through the demographic metabolism process, it may be possible to anticipate a future society with higher adaptive capacity.


[1] Butz WP, Lutz W, & Sendzimir J (2014). Special Feature, Education and Differential Vulnerability to Natural Disasters. Ecology and Society

[2] Lutz W, & Muttarak R (2017). Forecasting societies’ adaptive capacities through demographic metabolism model. Nature Climate Change 7 (3): 177-184.

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