In terms of cities and climate change, Miami Beach is the biggest canary in the coal mine. At approximately four feet above sea level, this 19-square-mile strip of artificial and natural islands faces frequent flooding during storms and high tides. (Last September’s king tide—a colloquial term for high tide—reached 2.2 feet.)

The city is aggressively fighting the watery onslaught: Over the next five years, Miami Beach will spend $400 to $500 million in anti-flooding defenses that include pumps, raised roads, and seawalls.

This is money well spent. The Miami area sits on limestone that absorbs floodwaters and can force the deluge back to the surface, making flood control a special challenge. Still, environmental concerns aren’t stopping new developments across Miami. The economic timeframe for developers (and the residents buying and renting) remains relatively short compared to the long-term threat.

In addition to flooding, another, more insidious threat looms: Miami maintains its Biscayne Aquifer by channeling freshwater from Lake Okeechobee to push back against saltwater intrusion, which means the region may have to choose between flooding or drinking salt water. By 2060, some estimates place sea-level rise at three feet. Further down the line, questions of how federal and private insurers will provide flood coverage
—and how eager banks will be to issue mortgages—may also arise.