Think it’s mainly about keeping it liveable now. Searise is a lost case anyhow for a place like Venice, 2100 or 2200 what’s the difference, It’ll be lost beneath the waves or hidden behind such a tall permanent seawall that the bay basically dies (and starts smelling, sanding etc). No-one is discussing really long term, at all concerning cc sealevels. Most coastal areas are just an illusion to keep dry long term (100+ years from now), there’s no turning back damages done. Planning with optimistic 2100 sealevels is really short term compared to the scale of the issue.