What this means is that life for most of the developed world will be lived in flats. In Hong Kong, Paris and New York that is already the case. But in London many people have been spared the restrictions of flat-living because of the age and the style of our housing stock. Family houses still exist in the centre of town for those rich enough to buy them and anyone willing to go east can still buy a house on a tube line for less than £80,000.
But the apartment blocks are growing. In Docklands, and further west along the river in Fulham and Chelsea, not to mention in many of the smarter sites in cities such as Manchester and Newcastle, the move is towards flats. So far they have been built with young singles and couples in mind.
Council tenants have been among the few forced to bring up children in flats. They are being joined by many couples trapped by negative equity who bought a flat five or six years ago never imagining they would still be there. Now, with space becoming increasingly tight, many others may have to follow in their footsteps and learn how to live as families in flats.
The key, according to those with experience, is having good outdoor space where children can play. Rene Fenby, who works for the BBC French service in London, chose to live in a flat here, having brought up her two children in an apartment in Paris. "What happened to me as a child and what I did with my own children was to go to the park every day," she said. "It was an absolute ritual.
"It was either the park, or the square - there are lots of those in Paris. They are like communal gardens, and they always have an area for the children."
The outing was as much a release for the mothers as for the children. She was surprised when English people used to ask "How do you cope with the children?" "I don't think anyone would miss a house and garden if they had this perfectly satisfactory ritual," she said.
John and Marie Rogers have sampled flat life in New York, Paris and London. They arrived in Paris with one daughter of six months and had a second while they were there. Their apartment was on a large floor of an old house, with three bedrooms, one very large living room, a good sized kitchen, bathroom and study. John Rogers thinks many English people are put off the idea of a flat because in England they tend to be small.
They were 10 minutes' walk - "even with small children" - from two of Paris's largest parks. "They cater for kids very well. They have better play spaces," Mr Rogers said. But they did miss the freedom of being able to open the back door and let the children run around. "You do feel under pressure to do things with them," Mr Rogers said. "You are always under pressure to take them out."
"Children in France start full-time nursery school at the age of three, but even then the ritual continues. "The `goter' (tea) is packed and off they go to the park," Mrs Rogers said. "Just about every churchyard or green space has some sort of climbing frame. The children can stop off and play for a few minutes."
When the Rogers returned to England they initially lived in a flat in Richmond. It had a garden, but seemed more awkward than living in a flat in Paris. "There it was normal; here it was abnormal," Mr Rogers said. They have sinced moved to a house in the same area.
Parks and open spaces may be the saving grace of Paris, but what about Hong Kong? Its famous skyscrapers tend to house companies rather than families. Although the majority of people live in flats, they are normally in low-rise blocks. Susan Bowden spent a year as an Army wife in Hong Kong, living in an apartment block away from the city centre. With summer lasting for eight months of the year and temperatures and humidity rising to unbearable levels, a swimming pool took the place of a lawn.
"Hong Kong is a very outdoor place," Mrs Bowden said. "All modern developments have a good play park."
As in Paris, space inside was not a problem, with flats designed for families with children. Rooms were big, the bedroom area was separated from the living rooms and there was plenty of storage space.
But while apartment complexes are built to suit children, the city is not. "People don't have buggies in Hong Kong because the streets are too crowded," Mrs Bowden said.
The places that made life bearable for these families have been described by Sir Richard Rogers as "open-minded spaces". We need to provide more of these - busy squares, markets and parks - and fewer of the "single- minded spaces" like car parks, housing estates and shopping malls, he argues, if city life is to become civilised once more.Reuse content