Safe and just Earth system boundaries

Area of Science:

• Earth System Science
• Environmental Science
• Planetary Health

Background:

• The stability of the Earth system and human well-being are interconnected but often studied in isolation.
• Under-recognition of these interdependencies leads to independent management approaches.
• This disconnect poses risks to both environmental resilience and human societies.

Purpose of the Study:

• To quantify safe and just Earth system boundaries (ESBs) across critical Earth system components.
• To integrate considerations of both environmental safety and human justice into boundary setting.
• To establish a quantitative foundation for safeguarding the global commons.

Main Methods:

• Utilized advanced Earth system modeling techniques.
• Conducted comprehensive literature assessments.
• Quantified ESBs at both global and subglobal scales for climate, biosphere, water, nutrient cycles, and aerosols.

Main Results:

• Justice considerations were found to be more constraining than safety for climate and atmospheric aerosols.
• Seven of eight globally quantified safe and just ESBs have been exceeded.
• At least two regional safe and just ESBs are exceeded across more than half of the global land area.

Conclusions:

• Current Earth system boundaries are largely exceeded, indicating significant risks.
• Integrated safe and just ESBs are crucial for maintaining planetary resilience and human well-being.
• The study provides a quantitative framework for managing the global commons for present and future generations.