Researched
Planetary Boundaries
In 2009 Johan Rockström and 27 colleagues named nine Earth-system limits, such as climate and biodiversity, that mark a safe operating space; by 2025 seven were crossed.
Open in the interactive tree →The Nature paper 'A safe operating space for humanity' covered climate change, biosphere integrity, land-system change, freshwater, nutrient flows, ocean acidification, aerosols, ozone depletion and novel entities such as plastics and synthetic chemicals, with quantified limits for seven of them. Updates in 2015 and 2023 found four and then six boundaries transgressed, and the 2025 Planetary Health Check added ocean acidification as the seventh. The framework turned a vague worry about global environmental change into numbers that can be tracked each year.
Prerequisites
- Ecology and the Ecosystem1935The biosphere boundary rests on ecosystem science.
- Ozone Hole and Montreal Protocol1987The ozone boundary and the idea of a global limit come from the Montreal Protocol.
- IPCC Climate Assessments1988The climate boundary follows the IPCC's assessments.
Unlocks
- Halting Mass ExtinctionopenBiosphere integrity is one of the nine boundaries and sets the target.
- Stopping Ocean AcidificationopenOcean acidification is a boundary and was reported as crossed in 2025.