Not long ago, demographers expected new technology tohollow out cities as people began to telecommute from tranquil suburbs. But no – even in weightless industries like finance people prefer to press into ever closer contact with each other inglass towers to do their exchanging and specializing, and they are prepared to pay absurdly high rents to do so. By 2025, it looks as if there will be five billion people living in cities (and rural populations will actually be falling fast), and there will beeight cities with more than twenty million people each: Tokyo, Mumbai, Delhi, Dhaka, Sao Paolo, Mexico City, New York and Calcutta. As far as the planet is concerned, this is good news because city dwellers take up less space, use less energy and have less impact on natural ecosystems than country dwellers.
The world’s cities already contain half the world’s people, but they occupy less than 3 per cent of the world’s land area. ‘Urban sprawl’ may disgust some American environmentalists, but on a global scale, the very opposite is happening: as villages empty, people are living in denser and denser anthills. As Edward Glaeser put it, ‘Thoreau was wrong. Living in the country is not the right way to care for the Earth. The best thing that we can do for the planet is build more skyscrapers.