As world leaders gather in Brazil for Rio+20, the Elders and Youngers answer your questions on sustainable development, the world we want and how we can achieve it.

Watch the Q&A videos of Fernando Henrique Cardoso, Mary Robinson and Gro Harlem Brundtland with the Youngers.

"We have not yet seen the necessary courage or political will to turn good intentions into effective, collective action."

In an opinion piece published in newspapers around the world, Gro Brundtland and Fernando H Cardoso outline the key steps that must be taken to guarantee Rio+20's success and lasting impact on sustainable development.