Climate Change Dilemma for Coastal US: How Much Flooding Is Too Much?

"In the Florida Keys, residents are facing a question that may soon plague communities up and down the U.S. coastline: How much water are they willing to live with?

During a bad bout of high tides in 2015, a Key Largo neighborhood flooded for 34 days, stranding and infuriating the people who live there. County officials responded by agreeing to raise the roads, but keeping them dry year-round would require making the roads 28 inches higher. That would cost $7 million for less than a single mile; extrapolated across the Keys, zero days of flooding was a goal more ambitious than the county’s 75,000 full-time residents could afford.

So the county adopted a new standard across the Keys: Roads should be elevated enough so that they would flood, on average, no more than seven days a year. That meant roads in part of Key Largo would be raised six inches instead. “We have to make tough decisions,” said Rhonda Haag, Monroe County’s sustainability program manager. As climate change gets worse, “there may be sections of road that have to go under.”"

Christopher Flavelle and Daniel Levitt report for Bloomberg July 12, 2017.