This interesting concept is by France- and Belgium-based Vincent Callebaut Architectures. Lilypad is a proposal addressing the rising oceans caused by global warming. As coastal inhabitants are displaced, floating Lilypad cities will house 50,000 inhabitants each. Lilypads will inhabit the water lines of the oceans, following the warm ascending Gulf Stream or cold descending Labrador. The shape of the cities is inspired by the ribbed leaf of the giant lilypad, Amazonia Victoria Regia. The cities also mimic the leaf's double skin, creating one made of polyester fibres covered by a layer of titanium dioxide, which is said to absorb atmospheric pollution. Lilypad takes up the four main sustainability challenges launched by the OECD in March of 2008: climate, biodiversity, water and health. It also claims to have zero carbon emissions and to produce more energy than it consumes.