Materials science is advancing rapidly.
For instance, Ventive Floathouse, led by engineer Michael Eliot, is developing a game changer material known as geopolymer concrete, which is carbon-negative and can last centuries in seawater. His experiments show its stronger, barnacle-resistant, easily repaired, sequesters C02, and is composed in part from fly ash, which is the byproduct of coal-burning normally disposed of in landfills. Floathouses will be carbon-negative and fly-ash-negative.
See our video: Seasteading! What About Pollution?