Nine guardrails for a stable planet.
The boundaries describe human pressure on critical Earth-system processes. They are interconnected guardrails — not nine independent environmental problems.
Climate Change
How much warming can the Earth system absorb before risks rise sharply?
Biosphere Integrity
How much life can we lose before ecosystems lose their ability to function?
Land-System Change
How much natural land can we convert without destabilising climate, water and ecosystems?
Freshwater Change
How much can we alter rivers, groundwater, soils and rainfall patterns?
Biogeochemical Flows
How much nitrogen and phosphorus can we add before natural cycles are overloaded?
Ocean Acidification
How much CO₂ can the ocean absorb before its chemistry becomes unsafe for marine life?
Novel Entities
How many human-made substances can we release before we outpace our ability to assess and control them?
Atmospheric Aerosol Loading
How much can airborne particles alter climate, rainfall and health?
Stratospheric Ozone
Can we keep the ozone layer strong enough to shield life from harmful ultraviolet radiation?