Barack Obama will skip a United Nations summit billed as a "once-in-a-generation opportunity" to make progress on global development, sending Hillary Clinton in his place.

As the global summit in Rio approaches, negotiations are still in flux, but some ideas that could advance the global sustainability agenda are gaining momentum.

As world leaders prepare for the Rio+20 meeting in just over a week, now is a fitting moment to assess the true legacy of the original Earth Summit in 1992.

Between 20-22 June, world leaders will join thousands of delegates, business leaders and NGOs at the decade-in-the-making Rio +20 summit.

The chair of an influential group of MPs lambasted David Cameron on Monday for not going to next week's Rio+20 Earth summit, saying it sent a signal to the world that Britain does not see sustainability as a priority and that the PM is not showing global leadership.

By Felix Dodds and Michael Strauss with Maurice F. Strong
Routledge Publishing, June 2012

New book Only One Earth looks back over what has been achieved in the past forty years since the United Nations Conference on the Human Environment in Stockholm, and ahead to what critically needs to happen at Rio+20 and beyond.  Written by Stakeholder Forum’s Executive Director, Felix Dodds, and Earthmedia’s Michael Strauss, with Maurice F. Strong, Former Secretary-General, “Earth Summit” [1992]; UN Conference on Human Environment [1972] and Executive Director, UNEP [1972-76].

Rachel Hall was part of a Unicef UK group that prepared a list of priorities that young people want to be taken up at the summit. She explains what they expect from world leaders.

Like many young people, I take the things most politicians say with a large pinch of salt. But I was genuine impressed by Caroline Spelman, the secretary of state for environment, when I met her on Thursday. I believed her when she pledged to speak for children at the Rio+20 Earth summit this month.