In some cases, residential lots, roads and parks are expected to be abandoned to the sea. That already happened in some parts of New York and New Jersey affected by Hurricane Sandy.
"This is not something that we can address alone," said Theodore Becker, mayor of Lewes, Del., a town of a few thousand residents that swells with summertime visitors.
The new analysis showed high tides could bring floods to Lewes every second day on average by 2045 - a risk that local and state leaders are toiling to reduce.
"We engage in at least two programs to educate people about what they can do to prepare themselves," Becker said. "We have a very engaged community. They get it."
To reduce future risks and impacts from current flooding, Lewes lawmakers recently adopted new rules for building and renovating homes in flood-prone regions. The city is also seeking funding from the state to elevate roads that frequently flood. It protects and enhances sand dunes, which can buffer floods.
"Lewes is an interesting example of a fairly proactive community in terms of sea level rise preparedness," said California-based climate scientist Kristina Dahl, one of the authors of the new study.