PussyGalore
Meow
Coming from a country of which three quarters of the surface area is already below sea level, I can tell you that there are definitely a lot of people who have legitimate reason to be wary of rising sea levels and subsequently of climate change.
How is it that your ancestors didn't know that sea levels change? This has been going on for thousands of years before modern industrialization. Hell, every ancient coastal civilization lost ports to changing sea levels; both by the sea extending further inland or receding away from land. For instance, there are ancient ruins of sea ports that have been discovered all over the Mediterranean, some underwater and some inland. It's been common knowledge for literally thousands of years that sea levels rise and fall all over the planet.
By the time the Netherlands began to coalesce into one unit the regional planners had to know of the yin and yang of the sea. There's no way they couldn't know it. Did they seriously suffer from such hubris that they thought reality would treat them differently this time around? Do they now believe that by blaming changing sea levels on mankind that that absolves them of responsibility for ignoring reality to begin with? It doesn't.
The bottom line is that if you decide to build a civilization below sea level in a coastal region then you have to accept the consequences for that decision in the long run. And trying to claim that changing sea levels are a man-made consequence when the truth is that it's been going on for millenia is pointless and stupid.