Global poverty is moving to the cities. Emma Joseph explores the dramatic increase in slums around the world

Two years ago, for the first time in human history, the number of people living in urban areas surpassed that of those living in rural ones. This has meant an exponential growth in the number of cities globally. In 1800, just 50 million people lived in cities. Today, three billion of us live in more than 100 cities around the world. And the growth of urban living is destined to continue: one million babies are delivered in cities each week.

According to UN Secretary-General Kofi Annan, "The locus of global poverty is moving to cities, a process now recognised as the urbanisation of poverty."

The mass migration of people from the countryside to the towns involves a host of problems, one of the most pressing being the dramatic increase in slums.

According to the United Nations (UN), 32% of the global urban population - or one billion people - now live in slums. This figure is set to double in the next 30 years unless urgent action is taken. Africa now has 20% of the world's slum dwellers and Latin America 14%, while in Asia more than 550 million people live in what the UN calls unacceptable conditions.

Slum dwellers constitute 60% of the population of India's most populous city, Mumbai. Many live in dreadful conditions, with little or no clean water, inadequate housing and high levels of infant mortality.

32% of the global urban population (one billion people) now live in slums. This figure is set to double in the next 30 years

The Booker prize winning novelist Arundhati Roy, who left her Kerala home at 16 and lived in a squatter's camp in Delhi to "make sense of her country", has been a vocal critic of the treatment of India's slum dwellers. "You have the huge poverty of India around you, the slums in the city.

Who are these people? They're the 33 million that have been displaced," she says. The Indian government's dam development programme has displaced 50 million of India's poorest people. "Then the government wants to bulldoze their slums," she continues. "People are so, so angry, but they're so helpless."

Reporting from Asia and Latin America as part of BBC World Service's season on the theme of land, I'm asking why there has been such a huge exodus of people from villages to towns. I'm exploring the day-to-day reality of living in a slum, from a basic lack of amenities, to the obstacles people face in raising and rearing a family. "Slumming It" also explores the chance of people ever getting out of the slums.

A chance the UN would like to convert into a guarantee - target 11 of the UN's Millennium Development Goal 7 is to "significantly improve" the lives of at least 100 million slum dwellers by the year 2020. How realistic is that goal, and what are governments doing to meet it?

While some governments have cleared away slums, replacing them with new housing. The problem is that slum clearances fail to address the wider social problems that cause them to grow.

Emma Joseph is a producer and presenter with BBC World Service. She joined the BBC in 1995 as a freelance researcher. Recently, she returned to her native Caribbean for a special series for BBC News on HIV/Aids

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