Homeowners in South Florida are willing to open their wallets for climate protection, but they would rather pay for mangroves than concrete barriers.
A new University of Miami study shows residents strongly favor nature-based coastal defense capabilities, with green infrastructure projects more than tripling their economic explosions compared to traditional seawalls. The study, which surveyed 850 households in Miami-Dade, Broward and Palm Beach counties, found that residents pay an average of $61 to $63 per household for mangrove and coastal dunes projects each year.
The numbers tell a green story
When researchers deal with economics, the results were surprising. For a hypothetical 10-mile mangrove project that lasted 50 years, residents’ willingness to pay $1.08 billion, four times the estimated $230 million construction cost. This means the welfare cost ratio is 4.7, while the seawall is only 2.0.
“I found that all projects pass what we call cost-benefit analysis, which means the total benefit will outweigh the cost,” said Haoluan Wang, assistant professor of sustainable economics who led the study. “Then, if we put those numbers in context, I found that green infrastructure will be more cost-effective than gray infrastructure.”
Preferences involve not only US dollars and meaning. The benefit-cost ratio of coastal dunes and beach restoration projects is 5.64, while traditional seawalls lag behind 2.02.
Why Green beats Gray
The attraction of a living seawall is intuitive. The mangroves not only prevent storm surges, but also provide wildlife habitat, isolate carbon and attract visitors. The salt marsh filters the water while providing a leisure opportunity. The renovation of the beach creates a kind of coastline that attracts visitors to Florida first.
In contrast, traditional seawalls provide protection, but few others are protected. They are purely functional barriers that can actually accelerate erosion on adjacent beaches.
The survey response reflects this multi-faceted value. Overall, residents supported about 64% of the proposed climate adaptation projects, and green infrastructure received the highest approval rate. The mangrove project received support from 67% of respondents, while Seawalls managed only 62%.
Flood factors
Geography forms preferences in a predictable way. Residents living within a 100-year floodplain showed a significantly higher willingness to pay for protection projects – a logical response given their higher risk.
Interestingly, risk aversion actually showed lower support for adaptation programs, which may reflect broader climate suspicion in this group.
The main findings of the study:
- All three infrastructure types prove economically viable, with benefits outweighing costs
- Green infrastructure benefits and cost ratio doubles the ratio of gray infrastructure
- Residents pay $106.80 per year for basic seawall protection
- Project life is directly related to cost-effectiveness – longer projects provide better returns
The meaning of the real world
The study arrives as South Florida fights sea level rise accelerates. Forecasts suggest that by 2030 and by 2060, the water level may climb 6-10 inches, and across the tri-county area, the water level may climb to 14-26 inches.
Local governments have begun to incorporate these findings into their plans. Miami-Dade County revised its climate action strategy in 2021 to highlight swamp and mangrove restoration, while Broward County outlines strategies for community-wide harm mitigation programs.
“Under this study, local governments can raise property taxes to a certain level and let residents know that the increase will be used to implement these projects, and people are satisfied with that,” Wang noted.
Fairness Question
However, the study also highlights potential pitfalls. Climate gentrification is imminent, as infrastructure investments may disproportionately benefit wealthier coastal communities with the highest property value (and tax revenue).
The study found that demographics of support levels vary widely. Familiarity with adaptation strategies strongly predicts willingness to pay, raising concerns about community participation in different groups of people.
What is the way forward? Data suggest that decision makers should prioritize green infrastructure while ensuring equitable implementation across the community. As sea levels rise, the question is not whether South Florida needs coastal protection, but whether leaders will choose solutions that work with nature rather than solutions that oppose it.
The study, published in the Journal of Environmental Management, represents one of the first comprehensive economic analysis of comparing different coastal adaptation approaches in the context of real-world policy.
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