Green Climate: South Florida residents are willing to pay more in taxes to fund both gray climate adaptation projects, like seawalls, and green ones, such as mangrove forests, but the benefit-cost ratio for green infrastructure projects is more than double that of gray, according to a University of Miami study.
The study, published in the Journal of Environmental Management, is one of the first to examine the cost effectiveness of coastal climate adaptation infrastructure by comparing the price tags of different projects with residents’ willingness to pay for them, said Haoluan Wang, an assistant professor of sustainable economics in the Department of Geography & Sustainable Development at the College of Arts and Sciences.
“Coastal areas in Florida are facing negative impacts from climate change and sea level rise, and now we have to think about different ways to adapt,” Wang said. “This is one of the first papers to put adaptation infrastructure cost and benefit numbers into context and provide additional evidence for policymakers.”
To research this issue, Wang surveyed 850 households in Miami-Dade, Broward, and Palm Beach counties about their preferences for three different types of climate adaptation infrastructure that help protect coastal areas from erosion: seawalls, mangrove forests and salt marshes, and coastal dunes and beach renourishment. Each project in the survey was tied to a specific increase in taxes. For example, residents were asked whether they would vote for 10 miles of new seawalls expected to last for 10 years if it meant that their household had to pay $25 more per year in taxes.
Wang found that South Florida residents strongly support coastal climate adaptation projects. The survey respondents said they were in favor of roughly 64 percent of the projects, with green infrastructure receiving the highest levels of support and seawalls receiving the lowest. In monetary terms, respondents said they would be willing to pay, on average, roughly $61 and $63 more per household per year for mangrove and coastal dune projects, respectively, than for seawalls.
After determining how much residents were willing to pay for different projects, Wang calculated how much total tax revenue could be raised for those projects using data on households in the study area. Then he compared those amounts with engineering cost estimates for each project.
What I found is that all the projects pass what we call the cost-benefit analysis, which means the aggregate benefits will outweigh the cost,” Wang said. “Then, if we put those numbers into context, what I found is that green infrastructure will have a higher benefit-cost ratio compared to gray infrastructure.”
For example, the aggregate willingness to pay for a 10-mile mangrove project with a lifespan of 50 years was $1.08 billion, the study found, but the estimated cost for such a project is $230 million, resulting in a benefit-cost ratio of 4.7. The benefit-cost ratio for dune and mangrove projects was more than double that of seawalls.
Wang said it’s not surprising that South Florida residents prefer green infrastructure over gray, since green infrastructure has additional environmental and ecological benefits, such as providing habitats for wildlife and attracting tourism.
Wang’s findings have important implications for policymaking in South Florida. The results indicate widespread support for public investment in climate adaptation infrastructure and suggest that policymakers should prioritize green infrastructure over gray.
“According to this study, local governments can increase property taxes by a certain level and let the residents know the increase will be used for implementing these projects, and people are fine with that,” Wang said.
This study is the second in a series on climate adaptation in South Florida that Wang has completed with support from a Provost’s Research Award. His previous study looked at socio-demographic disparities in residents’ familiarity with coastal climate adaptation strategies. Newswise/SP