Professor Andrew Hurrell talks on the upcoming Rio+20 Conference

Two decades after the Earth Summit in Rio, world leaders are to convene again at the Rio+20 Conference to discuss sustainable development. Andrew Hurrell featured on BBC Radio 4s The World Tonight to discuss what the conference, which is taking place later this month, could achieve.

"If one wanted to be optimistic about what might happen, " he said, "given the background of the global economic crisis, this is precisely the moment when refocusing development ought to be very firmly on the agenda of every major leader in the world, but there are enormous 'buts'..."

You can hear the whole programme here (Andrew appears at around 0.33.41 on the iPlayer clock).