The Sisters of Notre Dame have a very clear picture of this on their website and other links to follow.    http://rio-20-snd.com/2012/06/15/a-safe-and-just-space-for-humanity/

“Humanity’s challenge in the 21st century is to eradicate poverty and achieve prosperity for all within the means of the planet’s limited natural resources. In the run-up to Rio+20, this discussion paper presents a visual framework – shaped like a doughnut – which brings planetary boundaries together with social boundaries, creating a safe and just space between the two, in which humanity can thrive. Moving into this space demands far greater equity – within and between countries – in the use of natural resources, and far greater efficiency in transforming those resources to meet human needs. More information”   http://oxfamblogs.org/doughnut/  If you scroll down there is a 4 minute video explaining the dounut.  Well worth looking at!