So the waves only erode coastline when the sea is above the mean from the start of the industrial revolution? It can't cause a lot of coastline erosion because

So the waves only erode coastline when the sea is above the mean from the start of the industrial revolution? It can't cause a lot of coastline erosion because it's only 1.5 feet, and we have 100 years to prepare for the gargantuan task of adding some sandbags around a few low lying roads.