More of us live in cities than ever before. And every day, an estimated 180,000 people leave their homes in the suburbs or countryside to join in.
Fast forward and, according to the UN, by 2050 6.3 billion people - or 70 per cent of the world's population - will be city dwellers. Already, so-called megacities such as Tokyo and Sao Paulo have become monstrous, sprawling testaments to humanity; the foremost product of our impulse to master the environment, but portents reminders, too, that our mastery is still limited. Forget London's reputedly creaking public transport system - currently being tested against an influx of visitors to the 2012 Olympics - in Sao Paulo, around 2.5 million of the 17 million inhabitants still live in makeshift slum housing, without sanitation.
Cities are an inextricable part of our shared future. That means we need our cities to become more functional, more efficient, safer, and more beautiful. Now, the people behind a much talked-about new project say they have a radical answer. Or, rather, they say you and I have: City 2.0 (www.thecity2.org) is an online platform for crowdsourcing a vision of the 21st-century city. Last month, the project won the prestigious TED (Technology, Entertainment, Design) prize, the first time the award has been made to an idea rather than an individual.
TED makes the award of $100,000 (Dh367,300) to those who persuade it of a vision to change the world for the better. City 2.0 did just that, by helping to formalise the growing trend for architects, designers, artists and ordinary citizens to think creatively about how we can better live together in the cities of the future. Proponents call it "citizen-powered change", and a "big open tent" to share insight, resources, and success stories.
Thanks to the TED money, the Ugandan artist Ruganzo Bruno Tusingwire can make real his mad-but-beautiful idea to use thousands of recycled plastic water bottles to build an amusement park for the slum children of Kampala. The British designers Alastair Parvin and Nick Lerodiaconou have got funding for their Wikihouse project (www.wikihouse.cc), an open-source construction set that lets anyone build a plywood house using simple online templates. The pair hope Wikihouse technology will transform slums such as those seen in Sao Paulo and help after natural disasters when super-fast, cheap housing becomes a life saver. Meanwhile, mapmakers Asim Fayaz, Omer Sheikh and Khurram Siddiqi have won funding for a simple idea that will transform the maze that is their native Lahore (population 11 million): street signs, so that people can find their way around.
Got an idea to improve the lives of millions of 21st-century city dwellers? Visit the City 2.0 website, where anyone can throw suggestions into the mix. The TED curator Chris Anderson hopes the site will become a vast clearing house of communal ideas, a kind of Wikipedia for urban planning that will "empower citizens to connect with each other to help reshape their own cities".
The shape and function of our cities has, after all, always been shaped by ordinary city-dwellers: our daily travels, our consumer impulses, our capacity for meanness or generosity. Now we have the tools - it's about time we really put our minds to the job.