The Archbishop of Canterbury has reminded governments of the need to preserve the world for the next generation.
More than 130 heads of state and government are meeting in Rio later this month for another round of talks on the environment and sustainable development.
The UN conference is bringing world leaders together to negotiate a "green economy" and non-binding sustainable development goals in areas such as food security, water and energy.
In a recorded video message for the Rio+20 conference, Dr Rowan Williams ask leaders to think about the kind of world they want to leave to their children.
“All religious people see the world as a gift from God," he says. "And all religious people are therefore bound to ask: if that’s the gift we’ve been given, how do we make it a gift to others, to the next generation?”
The Archbishop encourages leaders to consider how mankind can "inhabit a limited environment with grace, with freedom, with confidence".
“Are we handing on a gift, both material and spiritual, that really will make them live well, live happily, so that their future will be secure and they too will have a gift to give to their children and grandchildren in turn?” he asks.
With environmental campaigners skeptical of progress at the conference, the Archbishop highlights the key role government and faith communities have to play in achieving sustainability.
He urged collaboration in order to secure an equitable and inclusive green economy.
“Governments can, of course, and must, play their part in all this," he said.
"Governments need to give fiscal incentives to green development. They need to promote programmes that encourage us all to reduce our waste.
"They need to ‘green’ our economy, both at home and worldwide. And we, all of us, not least the faith communities, need to collaborate in that and support governments in that vision.”
He added: “Big changes come because small changes happen.”
The video message can be viewed here