Stone Age settlement found under the sea in Denmark

> As today’s world faces rising sea levels driven by climate change, the researchers hope to shed light on how Stone Age societies adapted to shifting coastlines more than eight millennia ago.

Unfortunately I don't expect there is any particularly reusable solution to be uncovered. Ancient peoples facing rising tides almost certainly just walked a bit inland and built new huts there. They probably thought nothing of it. They were a far more physically mobile culture, without great dependence on immense, immovable infrastructure - nor on rigid land ownership rules.

Our culture's migration will be entirely different.

I think the rigidity of land ownership will be put to the test because of climate change.

I think for a lot of people, their deeded land is in eventually in terms of lat/long, and if the water swallows their land or their land falls in the sea, they're pretty much SOL. Depending on the rules of their locality, they may keep ownership of the land that's now underwater: it may effectively cease if underwater land is not subject to private ownership, or it may continue but not be of value because you may not be able to exclude other people from the land (or the waters above it) or develop it.

For some though, the deed may be defined in terms of the coastline, and then they're going to have an interesting legal battle. But this isn't without precedent; coastlines and waterways change and things defined against them adapt.