Study quantifies mangroves’ economic value in reducing storm surge damage

GREENVILLE, N.C. (10/16/2025) — A new interdisciplinary study spearheaded by East Carolina University faculty at the Coastal Studies Institute provides some of the most detailed estimates to date of how mangrove forests reduce property losses from tropical cyclone–driven storm surges in Florida. The findings underscore the vital role of mangroves as a form of nature-based infrastructure in coastal risk management and adaptation planning.

The study, titled “The spatially variable effects of mangroves on flood depths and losses from storm surges in Florida” (Narayan et al., 2025), uses high-resolution hydrodynamic and economic loss modeling to simulate flooding under two scenarios: one reflecting present-day mangrove coverage and a second fictional scenario in which all mangroves are removed. This work, conducted in partnership with industry risk modelers Moody’s RMS, the Center for Coastal Climate Resilience at the University of California Santa Cruz and The Nature Conservancy, combined industry risk models to estimate the net, location-specific benefits and trade-offs that mangroves provide by attenuating storm surges and reducing flood depths across the coastal landscape.

Key Findings & Impacts

• In Collier County (western Florida), mangroves reduce average annual property loss by approximately $67.5 million, which corresponds to a benefit of about $270,000 per square kilometer of mangroves per year.
• Mangroves reduced storm surge losses during Hurricane Irma (2017) by $725 million (14%) and Hurricane Ian (2022) by $4.1 billion (30%).
• The study found that most of the protective benefits of mangroves accrue from more frequent, moderate storm events (return periods under 30 to 50 years), rather than only the largest, rare storms.
• The protective effects are spatially variable. For inland properties, damages are invariably lower with mangroves present. However, for properties located between or seaward of mangrove patches, there can be mixed or even negative effects — in some spots, mangroves may redirect or concentrate floodwaters, increasing local inundation. Such nuance emphasizes the importance of high-resolution risk modeling and coastal planning.

“In this collaboration with the risk modeling industry, we show the value of mangrove forests in reducing property damages from storm surges every year. Similar to how salt marsh wetlands from New York to North Carolina reduced damages during Hurricane Sandy, coastal properties in Florida avoided anywhere between 14 to 30% in surge losses during hurricanes Ian and Irma due to mangroves acting as natural defenses,” said Siddharth Narayan, ECU and CSI lead on the project.

The results of this study provide actionable, quantitative evidence for the value of mangroves as a nature-based defense asset, offering a potentially cost-effective, sustainable element in coastal resilience strategies.

The paper is available on the Cell Reports Sustainability website.

Contact: John McCord, mccordr@ecu.edu, 252-475-5450 

###

East Carolina University News Services

Howard House, 1001 E. Fifth Street

Greenville, NC 27858

ecunews@ecu.edu

Phone: 252-328-6481