It’s 12-36 inches (a big deal at 6 feet elevation) but the bigger issue isn’t the average but the peak during storms and flood events with such water tables. That affects less obvious things like the sewage system, coastal erosion, etc. Billions of dollars in things like sea walls and disaster relief will probably keep Miami around as a major city but it’s not going to be cheap and the uncertainty over the period of a 30 year mortgage will have a big impact on the real estate market.

Here’s a report you might find interesting:

https://www.rff.org/publications/reports/florida-climate-out...

It's solveable but the cost will be huge. The immediate problem is drainage of rainfall. Even a slight rise in sea level will drastically reduce the rate of drainage and lead to frequent flooding. So roads and buildings will have to be elevated and new larger drainage channels dug, with pumps in some places.

Sea walls are ineffective with a karst substrate.

I remember this logic when multi-billion dollar multinationals were issuing and securitizing bad mortgages.

Didn’t pan out like they thought

Multi-billion dollar multinationals that mostly only care about the next quarter’s earning call?