Draft Declaration on Planetary Boundaries, from planetaryboundariesinitiative.org,

meant for the Rio+20 conference already. Here with a better seminal graph on the title page, as taken from the Nature article. For more info, see Resources on the project page. Still more info, like videos with experts etc. is at the Stockholm Resilience Centre site. The Declaration has been submitted to the Rio+20 process, see the text of the submission with an added reference to phosphorus threshold (the reference is copied below).
[ICO]NameLast modifiedSizeDescription
[PARENTDIR]Parent Directory  -  
[IMG]Figure1_Beyond_the_boundary.png2012-02-16 22:54 354K 
[ ]declaration_on_planetary_boundariesv1_large.pdf2012-02-17 02:12 406K 
[DIR]old_figure/2012-07-27 13:54 -  
[DIR]working/2012-02-21 18:41 -  
Some comments on the need of such a declaration see an article by Peter Roderick at stakeholderforum.org.

The Declaration is based primarily on the paper:
Rockström, J et al. Planetary boundaries: Exploring the safe operating space for humanity. Ecology and Society 14, 32 (2009). Available online at www.ecologyandsociety.org/vol14/iss2/art32.

A shorter text on the same theme appeared in Nature,
Rockström, J., W. Steffen, K. Noone, .. Persson, S.F. Chapin III, E.F. Lambin, T.M. Lenton, M. Scheffer, et al. 2009. A safe operating space for humanity. Nature 461: 472.475.
It is commented on the Nature site.

A later paper, finding that the planetary boundary for eutrophication of freshwater by phosphorus has been crossed already, is
Carpenter, S. R. & Bennett, E. M. Reconsideration of the planetary boundary for phosphorus. Environmental Research Letters 6, 014009 (2011). Available on the IOPscience site as a 0.5 MB pdf

In 2015, an update on the science of planetary boundaries appeared in Science. For more information, see the topics at stockholmresilience.org and its another page