The UN Summit on Sustainable Development is under way in Brazil. <br /><br />Also known as the Rio+20, or Rio Earth Summit, it is being attended by many of the world's most influential leaders. <br /><br />But Rio de Janeiro, the host city, is also home to some of the world's worst slums, and extreme poverty. <br /><br />Al Jazeera's Rob Reynolds reports from Rio de Janeiro.
