The Crisis: By 2100, rising seas could displace 630 million people and submerge coastal cities worth trillions. As U.N. Secretary-General António Guterres warns, "Low-lying communities and entire countries could disappear forever." Traditional land-based solutions—like resource-heavy reclamation—accelerate biodiversity loss, emit massive CO₂, and fail against storm surges. Coastal urbanization needs a radical rethink.