Sea rise could force millions in Florida to adapt or flee, study finds

If sea level rises 3 feet, 1.2 million people in Florida would be affected

The number of people threatened by rising seas fueled by climate change in the U.S. could be three times greater than previously estimated, with more than six million Floridians at risk under a worst-case scenario, according to a study published Monday.

For the first time, a team of researchers looked at ongoing population growth in areas where the National Oceanic and Atmospheric Administration has created flood maps that more accurately reflect local conditions. What they found was startling: projections that failed to factor in population growth in dense states like Florida hugely underestimated the number of people at risk and the cost of protecting them.

Combined with the findings from a 2015 report, that means Florida can claim two titles: most property at risk and now, most people.

“In terms of sheer number of people living in harm’s way [South Florida] is way at the top basically,” said Stetson University ecologist Jason Evans, one of three co-authors of the paper published in the journal Nature Climate Change. “It just pops out.”

Using the most conservative estimate of sea rise — three feet by 2100 — the team found that 4.3 million people are projected to live in coastal areas across the country expected to flood. Floridians account for 1.2 million. Using a higher estimate of six feet by 2100 — a number scientists increasingly say could be more likely given the faster melting of polar ice — the number of people triples to 13.1 million, with nearly half living in Florida. South Floridians account for a quarter of the statewide estimate, the authors said.

The findings could help planners determine where, when and what kind of fixes they want to make in advance of rising waters.