2026 Theses Master's

A fatal assumption: Examining the imperfect relationship between climate disaster damages and deaths

Maclennan, Ellie

Planners face increasingly climate hazard-burdened cities, introducing a host of risks to urban life. To plan for these hazards, planners must rely on tools to assess risks, many of which aim to combine risks across domains (e.g., people, buildings, etc.) to produce a singular risk metric. These risk indices assume risk to people and buildings can be combined, and can lead users to falsely believe areas of lower overall risk must be lower risk to people, too. However, while disaster risk research has expanded rapidly in the past couple of decades, one basic question remains understudied: how closely do climate disaster structural damages and deaths actually correlate, and what happens if these diverge? This study investigates the relationship between damages and deaths through correlation analysis at the national scale.

Findings suggest this correlation ranges widely by hazard type and state. How and where people died was also explored to begin to explore why this correlation may differ. Then, population resilience factors were explored to understand their role in predicting fatalities versus damages. While results varied across hazards, it appears factors that predict any deaths vary and are different from the predictors of the number of deaths, which was better predicted by damages for Winter Storms and Hurricane/Tropical Storms.

Lastly, in order to see how structural damages and deaths diverging impacts risk assessments, FEMA’s National Risk Index was recalculated to compare risk to people and risk to buildings, which were then contrasted against the NRI’s standard composite risk index. This analysis identified 20 counties (many of which are major cities) that had calculated risk to people values much higher than predicted by FEMA’s composite index. This illustrates the danger of assuming risks to buildings and people can be summed together to inform decision-making. Taken together, disentangling deaths from damage offers hope. If extreme disasters can occur without any deaths, eliminating climate disaster deaths is possible in the United States, so long as this target is made explicit.