Safe and just Earth system boundaries

The stability and resilience of the Earth system and human well-being are inseparably linked1–3, yet their interdependencies are generally under-recognized; consequently, they are often treated independently4,5. Here, we use modelling and literature assessment to quantify safe and just Earth system boundaries (ESBs) for climate, the biosphere, water and nutrient cycles, and aerosols at global and subglobal scales. We propose ESBs for maintaining the resilience and stability of the Earth system (safe ESBs) and minimizing exposure to significant harm to humans from Earth system change (a necessary but not sufficient condition for justice)4. The stricter of the safe or just boundaries sets the integrated safe and just ESB. Our findings show that justice considerations constrain the integrated ESBs more than safety considerations for climate and atmospheric aerosol loading. Seven of eight globally quantified safe and just ESBs and at least two regional safe and just ESBs in over half of global land area are already exceeded. We propose that our assessment provides a quantitative foundation for safeguarding the global commons for all people now and into the future. © 2023, The Author(s).

This work is part of the Earth Commission, which is hosted by Future Earth and is the science component of the Global Commons Alliance. The Global Commons Alliance is a sponsored project of Rockefeller Philanthropy Advisors, with support from the Oak Foundation, MAVA, Porticus, the Gordon and Betty Moore Foundation, the Tiina and Antti Herlin Foundation, William and Flora Hewlett Foundation and the Global Environment Facility. The Earth Commission is also supported by the Global Challenges Foundation and the Frontiers Research Foundation. Individual researchers were supported by the European Research Council (Grant on Climate Change and Fossil Fuel 101020082 to J.G. and Advanced Grant grant ERC-2016-ADG 743080 to J. Rockström), the Open Society Foundations (J.F.A. and T.M.L.), the Australian Government (Australian Research Council Future Fellowship FT200100381 to S.J.L. and Australian Research Council Discovery Early Career Researcher Award DE230101327 to C.N.) and the Swedish Research Council Formas (Grant 2020-00371 to S.J.L.).