Architect Vincent Callebaut has designed a city that floats on the ocean and can house 50,000 people. Why? Given the projections for rising ocean levels due to melting ice caps, a lot of land, especially coastlines, will be under water in the 21st century. As Callebaut explains,

According to the less alarming forecasts of the GIEC (intergovernmental group on the evolution of the climate), the ocean level should rise from 20 to 90 cm during the 21st century with a status quo by 50 cm (versus 10 cm in the 20th century). The international scientific scene assesses that a temperature elevation of 1°C will lead to a water rising of 1 meter. This increase of 1 m would bring ground losses emerged of approximately 0.05 percent in Uruguay, 1 percent in Egypt, 6 percent in the Netherlands, 17.5 percent in Bangladesh, and up to 80 percent approximately in the atoll Majuro in Oceania (Marshall and Kiribati islands and step by step the Maldives islands).

To combat this loss of livable terrain, Callebaut proposes building his rather brilliant floating cities, called Lilypads. Each Lilypad can support up to 50,000 residents, and relies on a type of design called biomimicry, which uses shapes found in nature (such as the nautilus) and then imitates these designs and processes to solve human problems. In this case, the Lilypad design is inspired by the shape of the water lily. It is half terrestrial and half aquatic, and includes features such as lagoons that purify rainwater. The city relies on renewal technologies such as solar and wind power, and is designed to float on gulf coasts. Even cooler? The city's tiatium dioxide "skin" is designed to process CO₂ in the atmosphere, thus helping to reduce climate change.

While this city is still in the very hypothetical stage, I find it reassuring that there are architects diligently working on ways to deal with these possible issues. It's especially heartening when such a beautiful design is presented.