Freeport, Texas levees
Mapping indicates that even at one foot of sea level rise, Freeport, Texas is below sea level. But a 53-mile levee system, shown in red, keeps water away from Freeport, the large Dow Chemical plant, and the Bryan Mound Strategic Petroleum Reserve—the country's largest SPR site with storage capacity of 254 million barrels. The map above at right shows the entire area of Brazoria county surrounding the levee under water at five feet SLR.
However, during Hurricane Ike in 2008, water came to within two feet of topping the levee. According to NOAA, a tidal surge of 6.25 feet was recorded near Freeport, and was estimated to be 6 to 8 feet at Surfside Beach. That indicates that the levee will keep as much as 8 feet of water back, but that leaves no room for high tides and storm surges when sea level is five feet higher than today.
From the U.S. Army Corps of Engineers fact sheet that requested funding for a 2012 risk survey:
The existing Hurricane-Flood Protection System protects the strategically important petrochemical industry in the Freeport Vicinity, including the Strategic Oil Reserves. Tidal surge from Hurricane Ike came within 2 feet of overtopping the levee in September 2008. If a tidal surge overtops the levee it would potentially endanger the lives of approximately 45,000 people, cause $6 billion dollars worth of commercial, residential, and public property in the Freeport area, and could cause disruption to the $20 billion-dollar, strategically-important petrochemical industry.
The question comes back to fight or flight: Building higher levees will hold higher waters back. But sea levels might not stop after five feet—that's an arbitrary number, and it's likely that over time it will continue to rise. However, moving towns and a very dense industrial zone presents real challenges.
20,000 years ago, at the height of the last ice age, ocean levels were more than 200 feet lower than they are today. On average, not accounting for the cycles of climate, that's a rise of less than one-eighth inch per year. Mankind didn't start farming until 18,000 years ago, and industrialized development has largely taken place only in the last 150 years. With the accelerated pace of today's warming climate, we are looking at water rising an average of close to three-quarters of an inch every year. This is not something anyone could have predicted. We have taken for granted that geologic and temperate change is slow. It's not now.