S14E7 - Greg Ferraro on the impacts of chronic sea level rise on coastal ag land values

Oct. 27, 2026 GES Colloquium | What happens when farmland’s future looks saltier?

Effects of Current and Future Chronic Sea Level Rise Exposures on U.S. East and Gulf Coast Agricultural Land Values

Greg Ferraro, PhD

Postdoctoral Researcher at OARS, University of Maryland, Profile

Full details at https://ges.research.ncsu.edu/event/colloquium-2026-10-27/ | Watch the video

Related links:

Salinity-Affected Lands in Transition (SALT) Program
Saltwater is seeping into Maryland’s coastal forests. This team is helping landowners prepare, Stanford School of Sustainability, 9/29/26

AI-generated Overview and Summary

This GES colloquium session featured a research presentation by Greg Ferraro, a recent PhD graduate in economics from NC State University and former AgBioFEWS Fellow with the GES Center, now a postdoctoral researcher at the University of Maryland. The talk focused on the economic impacts of sea level rise and saltwater intrusion on agricultural land values along the U.S. East and Gulf Coasts. Drawing on nearly 40 years of land transaction data and environmental exposure metrics, Greg presented evidence that coastal agricultural land is experiencing significant and measurable financial depreciation driven by chronic sea level rise — with landowner expectations of future conditions playing an outsized role in current land valuations.

Key Concepts or Theories

Ricardian Land Value Model: A framework linking land sale prices to current and expected future environmental and economic conditions
Saltwater Intrusion (SWiSLR): The process by which rising ocean levels push saline water into freshwater tables and cropland, causing soil degradation and crop loss
Coastal Flood Days: A localized metric recorded by tidal gauges indicating days when ocean heights cause overland flooding
Relative Mean Sea Level (RMSL): A localized measure of sea level change accounting for both ocean height and land subsidence
Forward-Looking Capitalization: The concept that landowners incorporate expectations of future environmental deterioration into current land prices
Resilience vs. Disaster-Response Policy: A policy framework distinction between reactive disaster payments and proactive, long-term resilience planning

Important Questions Raised

How do landowner expectations of future sea level rise influence current agricultural land values?
What behavioral changes are farmers and landowners making in response to chronic saltwater intrusion?
How should policymakers transition from disaster-based responses to resilience-based planning, and who decides how to allocate limited resources?
Can alternative land uses — such as aquaculture, wetland conservation, or carbon sequestration easements — offset the economic losses from saltwater-degraded farmland?
How does the financial framing of environmental damage affect public and policymaker understanding compared to ecological framing?

Key Takeaways and Summary of Learning Objectives

Agricultural land within 0.1 miles of the projected 2100 inundation zone has lost approximately 20% of its value relative to unexposed comparable land as of 2023.
Across 70 million acres studied along the U.S. East and Gulf Coasts, aggregate land value losses total approximately $6 billion.
The majority of land value depreciation is driven not by current exposure, but by landowners' forward-looking expectations of worsening sea level rise conditions.
Landowners appear to be relatively accurate in predicting near-term sea level rise trends, as evidenced by alignment between implied forecasts from land values and realized environmental data.
Saltwater intrusion damages are described as "unequivocal" compared to other climate-agriculture relationships, where yield impacts remain more contested.
Current U.S. agricultural policy is primarily oriented toward disaster relief rather than chronic resilience planning, representing a significant policy gap.
Interdisciplinary communication and collaboration are critical skills for researchers working at the intersection of economics, environmental science, and policy.

Topic 1: Sea Level Rise — Environmental Context and Observed Impacts

Global mean sea level has risen steadily since 1880, with an observable acceleration beginning around 2000. Expert forecasts project continued and potentially exponential increases through the end of the century, with even the most optimistic scenarios indicating substantial rise. Locally, this manifests through two key metrics: coastal flood days — the number of days per year when tidal gauges record overland flooding — and Relative Mean Sea Level (RMSL), which accounts for local land and ocean dynamics.

Using NASA Landsat satellite imagery of Dare County, North Carolina, Greg illustrated visible changes between 1985 and 2024, including expansion of marshland, dead vegetation, and saltwater-intruded cropland. At 2 feet of sea level rise — projected for approximately 2100 — entire coastal zones are expected to be permanently inundated. The most exposed areas in the study include New Jersey, Delaware, Maryland, Virginia, North Carolina, and Gulf Coast regions of Texas and Louisiana.

The primary mechanism of agricultural damage is saltwater intrusion: rising ocean pressure forces saline water into freshwater aquifers and drainage canals, depositing salt directly into soil — a phenomenon visually described as "salt burn" — causing crop failure and long-term soil degradation. Flooding duration also increases, as elevated water tables cause storm and rain water to pool for longer periods.

Relevant Q\&A

Question: "Can you go back to the slide showing the difference in farm sale prices and the coastal outlines? I noticed a lot of blank space in areas where I would expect farming activity. Is that due to farmers holding onto land, or a lack of trust in this kind of research?"

Answer: Greg noted that the dataset, while large, is incomplete due to county- and state-level variation in record quality. North Carolina, for example, had significant misclassification of agricultural land as vacant. Beyond data quality, variation in sales does reflect socioeconomic and cultural factors — rural landowners tend to hold land for heritage reasons, while more urbanized states like New Jersey show near-complete transaction coverage due to higher agricultural land turnover.

Topic 2: Economic Findings — Land Value Depreciation and Landowner Behavior

Greg employed a forward-looking Ricardian model to analyze approximately 440,000 agricultural land transactions recorded between 1980 and 2023 across the U.S. East and Gulf Coasts. The model separates the effect of current sea level rise exposure from the capitalized effect of expected future exposure, allowing for insight into both present damages and landowner forward-looking behavior.

Key findings include:

20% average value loss for parcels within 0.1 miles of the projected 2100 inundation zone as of 2023, compared to unexposed comparable sales.
More than double the estimated land depreciation when forward-looking expectations are included in the model, compared to current exposure alone.
Spatial concentration of damages: Nearly all aggregate losses are concentrated in the closest distance bin (within 0.1 miles of the inundation zone), with effects dropping sharply to approximately 1.5% at the next distance band.
Agriculturally abundant and high-value zone: The most affected coastal strip contains a disproportionately large share of cropland acres and commands some of the highest per-acre land values in the study area, partly due to coastal amenities and high agricultural productivity.
Landowners are holding onto exposed land rather than selling, suggesting that potential buyers — including urban developers — may share similar pessimistic expectations about future conditions, reducing demand.
Crop choice is shifting in exposed areas, though not uniformly toward salt-tolerant varieties. Market value, insurance availability, and hybrid seed options all factor into adaptation decisions.
Landowner forecasts are relatively accurate: Implied sea level rise expectations derived from land value changes closely track realized flood day and RMSL data over the study period, supporting the interpretation that forward-looking capitalization reflects genuine behavioral responses rather than statistical noise.

Relevant Q\&A

Question: "Your study looked at changes in agricultural land value with the most significant effects in the 0.1 mile inundation zone. Have you looked at changes in private property values within coastal areas, and would you expect to see similar patterns?"

Answer: Greg confirmed that existing literature on residential properties does show deterioration in coastal areas. While his research design was not specifically structured to isolate residential effects, his dataset includes residential sales as a control variable and does capture effects. He noted that residential coastal property involves additional complexity, including government-built protections, gentrification dynamics, and social equity considerations, making it a rich area for further study.

Question: "Could sea level rise be affecting sales because farmers are trying to sell damaged land — creating a selection problem in your data?"

Answer: Greg addressed this directly, noting that he tested the likelihood and timing of sales and found that agricultural land in exposed areas is actually less likely to be sold, not more. This finding reduces concern about selective selling of less productive land driving the observed price discounts. The higher baseline sale values in the most exposed zone further support the interpretation that the depreciation reflects genuine environmental capitalization rather than compositional bias.

Topic 3: Policy Implications and Future Research Directions

Greg argued that current U.S. agricultural policy is structurally misaligned with the nature of chronic sea level rise. Existing programs — including disaster payments and flood insurance — are designed for acute events such as hurricanes, not for the gradual, persistent degradation caused by saltwater intrusion. There is currently no coherent framework for prioritizing resilience investments, identifying cost-effective interventions, or distinguishing between landowners who are already self-adapting and those who need support.

Greg's postdoctoral work at the University of Maryland addresses several of these gaps through three interconnected initiatives:

OARS Project / SALT Research Program: Collaborative research with UMD's Agroecology Lab and Stanford's Wetlands Ecology Group focused on saltwater intrusion and natural resource management across the Mid-Atlantic.
Online Landowner Tool (developed with UMD App Club): A web application that allows landowners to input parcel information and receive tailored guidance on mitigation options, conservation programs, and technical assistance based on their objectives (e.g., continuing crop production vs. transitioning to conservation easements).
Sanford Internal Grant: An integrated modeling project combining econometric analysis, causal inference, and behavioral economics to evaluate Chesapeake Bay programs and develop a comprehensive picture of how landowners perceive and respond to saltwater intrusion — and how policy should evolve accordingly.

A field survey tool is also under development to help farmers and land managers visually assess the current stage of saltwater intrusion on their land.

Relevant Q\&A

Question: "Speaking of socioeconomic factors — you discussed the challenge of moving policy from disaster response to resilience planning. In reality, money is not infinite. How do you decide, or who decides, which approach to prioritize?"

Answer: Greg acknowledged that the information needed to make that determination does not yet exist in a usable form. There is currently no reliable way to assess the cost-effectiveness of resilience investments relative to disaster payments, or to identify which landowners are already self-adapting versus those who need intervention. He noted that disaster payments persist partly because they address immediate, visible losses with no alternative. He expressed hope that his research — by quantifying the costs of inaction through land value depreciation — can begin to frame that policy conversation more concretely.

Question: "Are there cases where landowners whose farmland has converted to marshland are being approached with alternative uses — such as wetland crops, aquaculture, or conservation easements — that could help them maintain land value?"

Answer: Greg confirmed this is a central focus of the UMD and Stanford research programs. Conservation easements, carbon sequestration credits, and recreational uses can generate meaningful income, and some landowners — particularly smaller operators — are receptive to ecological benefit framing. However, he cautioned that severe saltwater intrusion can cause ecological breakdown even in marshland, potentially leaving land unproductive in any capacity. He also noted that from a purely economic standpoint, if alternative uses were clearly the most valuable option, more landowners would already be pursuing them — though he acknowledged this framing may be insufficient from a policy perspective.

Question: "You mentioned that your postdoc position valued your interdisciplinary background, some of which came from AgBioFEWS. Can you comment on how this translates into your current position and what hard and soft skills you use daily?"

Answer: Greg identified communication as the most critical skill — specifically, the ability to convey research findings to audiences outside one's own discipline and to demonstrate relevance to interdisciplinary teams. He noted that economists are often brought in at the end of projects to "put a dollar on it," and that learning to contribute meaningfully during the planning phase of interdisciplinary work required deliberate effort. The AgBioFEWS experience provided both practical exposure to interdisciplinary collaboration and a credible signal to prospective employers that he could function effectively in such environments.

Actionable Next Steps / Assignments

Attendees are encouraged to complete the GES community needs survey on responsible AI literacy, initiated by Alice Cheng in the Communications department as part of a GES Center seed funding grant. The survey takes approximately 10 minutes and is accessible via QR code or link shared during the session.
Those interested in meeting with next week's speaker, Megan D'Amico from NC Biotech, should watch for communications to sign up for one-on-one meetings and a post-talk lunch. Her talk is titled "Growing North Carolina's Bioeconomy."

Supplemental Resources

Arizona State University dataset on insured crop loss: Recommended by an audience member as a potentially valuable complement to Greg's existing USDA-based data, particularly for analyzing acute versus chronic climate disruption and recovery curves.
AGU (American Geophysical Union) satellite datasets: Referenced by an audience member as containing well-organized soil moisture, salinity, and agricultural productivity data that could be integrated with Greg's economic modeling to build county- or state-level resilience curves.
University of Maryland paper on agricultural land converting to marshland: Referenced by Greg as complementary research documenting land loss that falls outside transaction-based datasets, as converted marshland cannot be captured in sales records.

__ Recorded from NC State’s GES Colloquium, this podcast examines how biotechnologies take shape in the world: microbiome engineering in built environments, gene editing and gene drives, forest and agricultural genomics, data governance and equity, risk and regulation, sci-art, and public engagement in practice.

Genetic Engineering and Society Center

Colloquium Home | Zoom Registration | Watch Colloquium Videos | LinkedIn | Newsletter

GES Center at NC State University—Integrating scientific knowledge & diverse public values in shaping the futures of biotechnology.

Produced by Patti Mulligan, Communications Director, GES Center, NC State

Find out more at https://ges-center-lectures-ncsu.pinecast.co