HARDtalk - Roger Martin, Optimum Population Trust Chairman

The human population is expected to increase from 6.9 billion in 2010 to more than 9 billion by 2050. Some argue the planet cannot cope, that family planning is a matter of survival and families should limit themselves to no more than two children. Carrie Gracie speaks to Roger Martin, chair of the Optimum Population Trust, who claims population control remains an 'irrational taboo' which is betraying generations to come.