The migration to cities and the high birth rates there are creating urban sprawls and suburbanization which annually consume tens of millions of hectares of open spaces. Vast conurbations with populations of multi-millions are created and continue to increase in size.
In the USA, for example, 25% of the population lives on 1.8% of the country's total land surface, creating, on the eastern seaboard, a megalopolis extending from Massachusetts to Maryland. Each year, over half a million hectares (equal to the state of Delaware) are built on or surfaced with (asphalt or concrete). In Europe 60 to 80% of the population lives in dense conurbations which increasingly take land from the surrounding area. This is true around Paris, in southeast England, in the built-up areas of the Ruhr, and in the Netherlands Randstadt, for example. In England and Wales, it is calculated that 80% of the 3 million new homes required by the year 2000 will urbanize an additional 11 or 12% of the land.