Aging in Place or Moving to Higher Ground: Older Adults’ Adaptation to Sea Level Rise in Honolulu, Hawaii

Coastal communities face escalating risks from rising sea levels and the increasing growth of vulnerable, aging populations in high-risk zones. These threats are expected to intensify as population growth and aging trends continue. In response to these challenges, this study represents a novel investigation into the synergistic impacts of demographic shifts and climate change in shaping the vulnerability of coastal communities, particularly focusing on elderly populations. This study’s primary objectives are to assess the potential impacts of these threats on vulnerable older adults and to explore effective adaptation strategies. To achieve these objectives, we used census tract data from Hawaii and the Hamilton–Perry cohort-component method to project the elderly population trends in each census tract for Honolulu in 2050. The vulnerabilities of older adults were estimated under different sea level rise level conditions and mapped according to three planning scenarios: (1) maintaining the status quo; (2) relocating or redeveloping vulnerable elderly residents to safer, low-density neighborhoods; (3) relocating or redeveloping vulnerable elderly residents to secure, high-density areas with amenities for older adults. We further evaluated transportation accessibility to emergency services in these scenarios. The findings reveal that with a projected sea level rise of 1.1 feet, the number of elderly individuals without timely access (within 8 min) to emergency and healthcare services would double by 2050. This is primarily attributed to reduced transportation access and increased aging in high-risk areas. Compared to the status quo, both relocation (or redevelopment) strategies significantly improve the vulnerable elderly population’s access to emergency and healthcare services, even without enhancements in transportation and infrastructure. Given that many developments and aging trends are yet to fully unfold, we propose that existing adaptation strategies should prioritize land use development, along with housing and transportation solutions that align with development scenarios 2 and 3, to support age-friendly activities and lifestyles. By directing population growth towards less vulnerable zones in the coming decades, we can achieve protective effects equivalent to those of future relocation efforts, but without incurring substantial protection or relocation costs.