Delaware state climatologist says Bethany Beach could face far more frequent minor tidal flooding by 2050

Kevin Brinsen, Delaware’s chief climatologist and director of the Center for Environmental Monitoring and Analysis at the University of Delaware, told a Bethany Beach meeting that rising sea levels are already increasing coastal flood frequency and that the trend is likely to accelerate.

Brinsen said long-term tide-gauge records from Lewes show sea level rise averaging about 1.5 inches per decade over the full record and roughly 2.2 inches per decade in the most recent 40 years. “By 2050, you’re talking about somewhere between 140 to 200 days per year,” he said, referring to the number of days the Lewes gauge would exceed the National Weather Service’s minor-flood threshold under central scenarios.

The projection matters locally because the town’s low-lying areas, including Fred Hudson Road and neighborhoods near the Loop Canal, are already showing regular tidal inundation at the minor-flood threshold Brinsen used. He emphasized that the graphs presented focused on tidal-related flooding (sea level and tides) rather than rainfall-driven street flooding.

Brinsen summarized how the state produced its localized projections: researchers downscaled data from 13 global climate models and examined a set of scenarios that differ mainly by future greenhouse-gas emissions and the amount of ice-sheet loss. Depending on the scenario, mean annual temperatures for Delaware could rise 6°F to 10°F by 2100, and the growing season could lengthen by 30–60 days.

On precipitation, Brinsen said models show a small upward trend but greater variability; extreme convective rainfall events remain difficult to project with confidence. He cautioned that some results, especially large ice-sheet contributions to sea level, are less certain beyond midcentury.

During audience questions, Brinsen explained datum and threshold issues when asked whether the charts combined rainfall and tidal flooding: the graphs were counting days above NOAA’s minor-flood threshold and did not include short-duration, rainfall-driven street flooding. He also said local vertical land motion contributes to relative sea-level change — “we’re sinking at maybe a millimeter a year” — while larger ice-sheet contributions are uncertain on decadal timescales.

Brinsen pointed listeners to forthcoming state products and tools, including a coastal flood exposure mapper and the state’s updated climate projections report, which the state plans to release alongside the climate action plan early in 2026. “That should come out sometime later this year, early 2026,” he said.

The presentation and the question-and-answer period highlighted the difference between tidal exposure (the subject of the projections) and storm- or rainfall-driven flooding that town staff also track. The town will present additional local analysis and public workshops later this year.