The Optimum Population Trust is holding a conference on how population growth will affect climate change, with a leading environmentalist, Dr Martin Desvaux warning that the UK will be unable to reach its carbon emission reduction targets whilst sustaining its population. Correspondent Caroline Duffield reports from Lagos, Nigeria on the problems caused by a rapidly growing population, while correspondent James Rodgers reports from Moscow, where the population is shrinking. Professor John Guillebaud, professor of family planning and reproductive health at UCL, discusses how population growth can be brought down without infringing on people's right to reproduce.