Flood risks expected to grow across Florida due to climate change

by Andrew Morrell

Global climate change has already done a great deal to reshape the landscape in Florida and elsewhere. A new report from Zillow in partnership with Climate Central takes a new look at areas where major flooding is expected to occur every 10 years on average. Unless worldwide greenhouse gas emissions are dramatically cut, these 10-year floods are expected to grow more widespread for the rest of the 21st century.

While they may be known as 10-year floods, these events are growing more common due to climate change and sea level rise. More alarmingly, Zillow found, was the rate of housing development in coastal states most at risk for more frequent and damaging flood events in the coming years. Even though 10-year flood zones have not grown as much in Florida as they have in several other coastal states over the last decade, many of these areas still are seeing rapid population change. Climate Central estimated that in just the last 10 years, 2,645 homes have been built in parts of Florida where major flooding is expected to occur about once per decade on average by 2050. Only New Jersey has built more homes in areas at high risk for flooding once every 10 years by 2050.

The Miami area hasn’t built as many new homes in high-risk areas lately, although plenty of existing homes are still at greater risk, assuming sea levels continue rising at roughly the same rate. A map of areas where annual flooding is expected by 2050 includes large portions of western Miami Beach south of 41st Street. Much of the coastline along the mainland would also be at greater risk, although flood risks would be unchanged for most inland areas.

Across all of Florida, homes within the 10-year flood zone by the year 2100 would increase to between about 700,000 and 1.6 million, depending on global greenhouse gas emissions.

“Overall, sea level rise is making the odds of a South Florida flood reaching more than 4 feet above high tide, by 2050, on par with the odds of losing at Russian roulette,” wrote Benjamin Strauss, CEO and chief scientist of Climate Central, in a previous article. “Miami-Dade and Broward counties each have more people below 4 feet than any state, except Florida itself and Louisiana.”

Climate Central’s study echoed a report issued last year by the Union of Concerned Scientists. In that report, researchers projected that, as soon as 2030, 2,600 homes in Miami Beach could be inundated by floodwaters. That number is expected to grow to 45,000 by 2045.

Many factors are at play in these scenarios that make an accurate risk assessment difficult, however. For one, sea levels could rise at a different rate depending on how much, or how little, the world is able to control climate change in the future. Climate Central factored in protection from existing levees and dams in their analysis, too, although they noted that a separate study by the American Society of Civil Engineers found most flood protection features inadequate nationwide. South Florida is also in a unique situation due to its geology: Much of the state is composed of porous limestone bedrock, making flooding possible even in areas with some man-made protection.

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