We can't stop sea level rise, and rebuilding all those coastal cities on higher ground is far too expensive (and would produce too much carbon pollution). So we have to find a way to keep them livable even as the waters rise. Photo CC 2009 by Robert Payne: https://www.flickr.com/photos/rob_moments/9534629478
Electric cars and buses would be built or retrofitted as amphibious vehicles, easily transform into boats to traverse flooded areas where the streets become canals. Networks of sidewalks modeled on floating piers, with occasional drawbridges over the canals, would enable pedestrian and bicycle access. Shorter buildings would be the biggest challenge. Some might be converted into houseboats, while new materials might enable others to become inverted aquariums on the new seafloor, with roof entrances where you can dock your boat-car.