In Miami Beach, the city engineer, Bruce A. Mowry, has come up with a plan for combating the flooding. He rips up problematic streets, raises them with extra dirt and repaves them, installing new drains and giant pumps that can push water back into the bay. The approach has already been shown to work in several neighborhoods.

A controversy has erupted about whether Miami Beach is polluting Biscayne Bay with the water, but the city is pushing ahead. Miami Beach plans to spend at least $400 million on its plan by 2018, raising the money through fees imposed on homes and businesses.

The huge county government for the region, Miami-Dade County, is developing its own resilience strategy, one likely to cost billions. It has committed to rebuilding some of its decaying infrastructure, like a sewage plant, in a way that safeguards against sea-level rise and storm surges.

“I don’t see doom and gloom here; I see opportunity,” said Harvey Ruvin, the clerk of courts for Miami-Dade County, who has been a leading voice on the environment in Florida for a half-century, and who recently led a county task force on sea-level rise. “We’re talking about the most robust possible jobs program you can think of, and one that can’t be outsourced.”

Many of the Republican mayors in the region are on the same page as Democrats in requesting national and state action on climate change, as well as pushing local steps. James C. Cason, the Republican mayor of Coral Gables, has convened informational sessions that draw hundreds of residents, and he has received no complaints for his stance.

“I hope in coming years when we have to spend a lot of money, the citizens will still support it,” Mr. Cason said in an interview.

Still, his city, and others in South Florida, have some hard decisions to make.

Some property owners cannot afford to raise their sea walls, putting their neighborhoods at increased risk of flooding. Will they be held legally responsible when floods do occur? A strict policy could force some people from their homes. Conversely, should public money be spent to do the work, even if it largely benefits private property?