Alternative voices from Rio+20

Direct from the alternative presentations at the Rio Plus 20 conference, you will hear two short hot speeches on the economy that's never counted, and the assault on a new science of planetary boundaries. Independent environmental journalist Stephen Leahy sent us the exclusive audio of Kate Raworth and Johan Rockstrom in Rio.

Then we'll journey to Australia. The self-sufficient John Morgan tells us about his 9 star home that needs no furnace or air-conditioner. Plus a look at Australia's new carbon tax, coming into effect July 1st.

But first, a group of 21 scientists, from very different fields of study, produced a special briefing for the Journal Nature, ahead of the meeting of world leaders in Rio de Janeiro for the second Earth Summit.

They concluded Earth, our planet home, could be heading for a massive shift, a new state not seen for millions of years. It's spine-chilling, so I'll need to call on my radio side-kick for this program, none other than Charles Prince of Wales.