| Sumario: | Background
Studies have documented the effect of increased nuisance high-tide flooding on traffic disruption and delays as well as infrastructure maintenance and repair costs. Recent research suggests that high-tide flooding is also associated with more extreme outcomes, including increased mortality risk among adults aged 65 years and older. The aim of this study was to leverage these new findings to project future premature deaths and associated economic costs among older adults in coastal areas of the USA throughout the 21st century under various climate change scenarios.
Methods
We estimated the relationship between global sea level rise and high-tide flooding. We then employed five projections of relative mean sea level from the Fifth National Climate Assessment to develop a probabilistic distribution of high-tide flooding scenarios. Combining population and baseline mortality projections with published estimates of the association between high-tide flooding and premature mortality among adults aged 65 years and older in Florida, USA, we generated a distribution of predicted high-tide flooding mortality impacts across coastal areas of the USA. Because this analysis assumes no change in adaptation strategies, we also presented a stylised scenario that assumes additional action is taken to limit mortality risk.
Findings
Our main specification (without additional adaptation) anticipates approximately 230 additional deaths of older adults per year in 2020 relative to 2005, corresponding to monetised damages of US$3·1 billion. By 2100, the model projects nearly 10 000 additional deaths in this age group per year under the same scenario, a 43-fold increase relative to modelled 2005 levels. With some protective measures, the model predicts 5700 additional premature deaths, representing a 57% reduction relative to the main results.
Interpretation
The cost of premature mortality in older adults is greater in magnitude than other modelled effects of climate-induced high-tide flooding (eg, value of lost time due to traffic delays). Results suggest further action is needed to (1) identify and protect components of road networks critical for emergency access, (2) build additional, more accessible critical care delivery facilities, and (3) manage the retreat of vulnerable populations to areas with better access to critical care facilities.
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