A Safe Operating Space for Humanity
Johan Rockström et al.
Nature 461, pp. 472-475
Full Text 
A sample of the international media coverage of this study:
BBC News  (UK): Humanity needs to take 'giant leap'
Sydney Morning Herald  (Australia): Planetary boundaries overstepped
Discover Magazine : 9 Eco Rules Humans Shouldn't Break If We Want to Survive
Miller-McCune : Planetary Boundaries? Go Ask the Romans
Scientific American : Setting boundaries: 10 guidelines to save Earth
Scientific American podcast : Are we pushing Earth's environmental tipping points?
Wired : 9 Environmental Boundaries We Don't Want to Cross
Spike TV : Planetary Boundaries