So, I just had a fun experience in my game wrt. the whole Flood Barrier cost escalation. I played Kupe, and my capital was naturally on the cost. Not a lot of tiles were going to be submerged, but I wanted to build flood barriers anyway. I was a bit late to the party, focusing on culture rather than science, so I think GW was up to level 2 before I got the barriers started. This would probably be early modern era. Game ended with a few turns left of atomic era, and my capital was still building flood barriers. This was probably 60 turns later or more. At this point there were still 18 turns remaining on the production time.
Now it's not like my capital was a production powerhouse, but it was still within reach of an industrial zone with power plant and it was a pretty big city. I just let it keep producing to see if it would actually ever get to finish the barriers, but as others have also reported, the sea level kept rising and raising the cost faster than I cut turns off. This was a large map, we were three civs doing a moderate CO2 release (on a map scaled for 10), one additional civ doing minor release, the rest barely any, and deforestation was only up to 10 %. So I definitely feel something needs to be done about the production scaling of the flood barriers.
