This paper attempts to numerically evaluate some of the main 'sustainability' problems facing our society. It is a similar approach to that of the Natural Step, which outlines the four sustainability principles that cannot be violated to ensure a sustainable society operating within the ecosphere.

The research put forth in Nature is a first attempt at identifying those limits, which is tricky business. In identifying planetary boundaries, we can show how close we actually are to crossing the 'rough' limits we've defined for the system. At the same time, it may encourage inaction on issues where we still have some wiggle room.

For more thoughts on the proposed framework (which is actually based in Stockholm), check out the following article and comments added by leading experts on a few of these issues.