Does anyone really know if there is any global warming much less any of the man made kind?
Yes absolutely the planet has warmed, then cooled, then warmed through history, and mostly predated human life.
During those non-human timeframes, oceans rose and shorelines changed widely.
What is missing is solid evidence that mankind has had a significant impact. The proof is not there.
Sunspot activity is probably a better explanation over history, than a few decades of internal combustion engines and fossil fuel burning electric power plants.
In the truly big picture, it would be highly pretentious to assume mankind could hold back a rising sea level to any meaningful extent.
It would be wise to investigate Holland and similar locations, for short term adaptations and measures.