A National Oceanic and Atmospheric Administration gauge at Virginia Key, just off the Miami shoreline, had an average sea-level height from 2012 to 2016 that was about 4 inches higher than the average from two decades earlier. At Lake Worth, a bit further north on the coast, there has been a similar increase since the mid-1980s. A gauge near Naples, Fla., saw a jump of about six inches from the early 1980s to the most recent five-year period.

If the sea is higher, it takes less additional rain to cause a flood, especially at high tide. Superstorm Sandy in 2012 saw massive flooding, thanks to the combination of heavy rain, a high tide — and higher overall sea levels. That’s why Miami floods regularly now, so much so that real estate agents are making long-term bets on property in the Miami area that’s higher above sea level.

AD

AD

Sam Purkis, a marine geologist at the University of Miami, told Scientific American that such moves might not be enough.

“What will happen, more than likely, is that you’ll have one big hurricane, and you’ll get a big inundation into the city,” Purkis said. “And that will serve to rot out the infrastructure — the sewer lines, the electricity, the telecoms. Everything that’s under the road. That becomes very costly to keep replacing every time this happens.” … [H]igher ground won’t be pleasant with “all of the rotting detritus and just general mayhem that that’s going to cause,” Purkis said. “So by the time the city starts to flood, it’s probably not great to be in the high areas either.”

This isn’t just happening near Miami. Across the world, and particularly on the Gulf Coast, sea levels are rising fairly quickly.

Sea-level trends

Why? Two main reasons with one cause. The first is that land-based ice is melting, meaning more runoff into the oceans. Second, oceans are warmer than they used to be, and warmer water occupies more volume. The common thread there, as you’ve probably realized, is global warming.

There have always been floods. There has always been melting ice. There have always been storms, and there have always been hot days. That those sentences are all true doesn’t undercut the abundant data that the world is warming and that the result will probably be storms with more intense precipitation, hotter days more frequently, more rapidly melting ice and quicker coastal floods. Not everywhere, not consistently and not all at once. But, scientists say, that’s the trend.