Many of the world's largest coastal cities are sinking at alarming rates due to factors such as groundwater extraction and the weight of built infrastructure.
A potential solution is moving their residents to floating cities, if they can be built without creating a damaging ecological footprint in the ocean.
The issue of land subsidence or 'sinking' is not a new one. Vertical subsidence of up to 9m has been observed in coastal areas during the 20th century.
