Planetary boundaries, equity and global sustainability: why wealthy countries could benefit from more equity

The planetary boundaries concept, which aims to define a safe operating space for humanity within the dynamics of the Earth System, has often been criticised on the basis of a presumed conflict between global equity and environmental sustainability goals. However, a re-analysis of the equity-environmental sustainability relationship suggests that significant synergies can be developed to build a more unified approach for working towards global sustainability. The synergies are especially strong for those planetary boundaries based on processes that are aggregated from very heterogeneous distributions at sub-global levels. It is possible to address the biophysical aspects of these boundaries from an Earth System perspective in ways that often may be, and sometimes must be, compatible with enhancing many aspects of social equity. Furthermore, it may well be in the self-interest of wealthy nations to achieve a more spatially equitable world in terms of access to resources and ecosystem services. Combining social equity considerations with the biophysical planetary boundaries approach may therefore constitute a necessary, and perhaps even sufficient, condition for achieving global sustainability.