Annual Report 2025: Population and Just Societies Program Highlights

Population aging is reshaping societies worldwide, raising new questions about how aging should be measured and addressed in policy. IIASA research advanced new approaches to demographic change.

A key study examined how aging is measured in research and policy. A review analyzed 211 studies in consumer behavior research and found that chronological age – simply counting years lived – remains the dominant measure. However, aging is more complex, reflecting differences in health, capabilities, and social participation across the life course. The study calls for stronger interdisciplinary approaches that draw on insights from demography and gerontology to develop more meaningful measures of aging.

Another line of IIASA research focused on population aging and demographic change. Sergei Scherbov, coauthor of the study, developed a framework that measures aging consistently from both cross-sectional and longitudinal perspectives, allowing researchers to better understand how populations age over time.

The work also explored strategies to address population decline in low-fertility countries, particularly in Eastern and South‑Eastern Europe. The analysis showed that reducing premature mortality, through stronger health systems and disease prevention, could slow population decline more effectively than policies aimed at increasing birth rates.

“Governments have already made massive investments in citizens’ education and health,” says Scherbov. “When people die prematurely from preventable diseases, that societal investment is lost.”

Together, these studies highlight the importance of better aging metrics and stronger health policies to respond to demographic change.

Further information: pure.iiasa.ac.at/20893, pure.iiasa.ac.at/21298

Climate change is often linked to displacement and migration, but a 2025 IIASA-led study highlights those who cannot move, revealing an urgent and often overlooked challenge for climate adaptation.

The research shows that many vulnerable groups remain “trapped” in high-risk areas due to economic hardship, social constraints, or political barriers, including people living in informal settlements, conflict zones, or regions with limited resources to support relocation. Their needs are frequently overlooked in climate and disaster planning, leaving them exposed to escalating risks.

“Involuntarily immobile populations are large and varied in their exposure to different threats,” explains lead author Lisa Thalheimer. “Cultural and legal barriers, limited access to humanitarian assistance, and other constraints, such as conflict and poverty, make the livelihoods of such populations particularly vulnerable to climate-induced threats.”

Conducted through a wide international collaboration including partners from IIASA member countries such as the United States and Germany, the study identifies practical ways to better support these populations. These include improving local infrastructure, strengthening basic services, and explicitly considering immobility in climate risk assessments and policy design. The findings emphasize that protecting people in place is as important as managing migration.

The study calls for more inclusive approaches that recognize different forms of vulnerability and ensure that adaptation strategies reach those most at risk. By shifting attention to immobile populations, the research broadens the scope of climate action, highlighting the need for solutions that safeguard both those who move and those who cannot.

Further information: pure.iiasa.ac.at/20455

Demographic change and evolving education patterns are reshaping labor markets across Europe. IIASA research advanced new tools to better understand future workforce dynamics and support policy decisions.

A recent study used the Link4Skills‑Mic dynamic microsimulation model to project labor supply across the European Union up to 2060. Developed under the Horizon Europe Link4Skills project, the model integrates demographic and education dynamics to explore how workforce skills may align – or fail to align – with future job requirements.

The results point to growing structural mismatches. While the number of highly educated workers is projected to rise, this does not automatically translate into better labor-market outcomes.

Instead, overqualification may increase in some sectors, while vacancies persist in others. The researchers tested several policy options, including expanded training, increased migration, and longer working lives. The analysis shows that no single measure can resolve emerging skill gaps. Instead, coordinated policy packages will be needed to address labor-market imbalances in Europe’s aging and increasingly knowledge-based economy.

The Link4Skills research builds on broader work strengthening the evidence base on human capital. Last year, the group advanced methods for education reconstruction, migration-flow forecasting, and subnational population projections.

IIASA researchers also launched EduCohorts, aimed at improving the demographic consistency of literacy data. In parallel, the Skillsin‑Literacy Adjusted Mean Years of Schooling (SLAMYS) dataset was extended to 2025, providing improved global indicators of skillsadjusted human capital.

Further information: pure.iiasa.ac.at/21058, pure.iiasa.ac.at/21056, pure.iiasa.ac.at/21055, pure.iiasa.ac.at/20773, pure.iiasa.ac.at/20889

Nature-based solutions (NbS) are increasingly promoted to address climate-related risks and support disaster resilience. However, turning these ambitions into real-world projects requires stronger governance frameworks and better financing mechanisms.

IIASA research advanced the understanding of how NbS can be implemented and scaled. Across projects including HuT, NATURANCE, Firelogue, and the completed PHUSICOS initiative, seven publications examined how governance structures, financing, and stakeholder collaboration shape the success of NbS for climate adaptation and disaster risk reduction.

A key study highlighted a persistent gap between political ambition and implementation. Although NbS are widely supported in policy discussions, their uptake remains limited due to governance challenges such as insufficient expertise, limited evidence on effectiveness, and conflicts among stakeholders. The research emphasizes that overcoming these barriers – through co-design processes, clearer guidance, and more coordinated governance – will be essential to move from planning to action.

Other studies explored pathways for scaling NbS through policy, finance, and capacity-building innovations. Achieving global goals will require integrating these approaches into land-use planning, regulatory frameworks, and public investment strategies.

Additional research examined community insurance mechanisms supporting NbS, governance of urban green spaces, and lessons from disaster risk reduction and early warning systems.

Beyond academic research, IIASA researchers also contributed to a chapter of the European Commission expert report Policy Imperatives for a Competitive and Resilient Nature‑Positive Economy (2025), synthesizing evidence from EU NbS projects to inform implementation and financing discussions.

Further information: pure.iiasa.ac.at/20638, pure.iiasa.ac.at/20339, pure.iiasa.ac.at/21049