Motorcycle taxi riders, known locally as a 'boda bodas', ride through a busy street market in the Kangemi district of Nairobi, Kenya.
(Bloomberg) -- With 10 billion people expected to cram into urban areas by mid-century, the world will add at least 14 new megacities — many of which are at risk of threats including food and water insecurity, conflict and high crime rates, as well as climate-change related disasters like flooding and drought.