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Table 1 Summary of the Planetary Boundaries (adapted from Steffen et al. [12], Table 1)

From: The Planetary Accounting Framework: a novel, quota-based approach to understanding the impacts of any scale of human activity in the context of the Planetary Boundaries

Earth system process Control variable Planetary Boundary
Climate change Atmospheric concentration of carbon dioxide ≤ 350 ppm
Change in radiative forcing ≤ 1 W/m2
Biodiversity loss Global extinction rate ≤ 10E/MSY
Nitrogen and phosphorus cycles Reactive nitrogen removed from the atmosphere ≤ 62Tg
Phosphorous flowing into oceans ≤ 11Tg
Stratospheric ozone depletion Stratospheric concentration of ozone measured in Dobson Units (DU) ≤ 5% below pre-industrial levels (290 DU)
Ocean acidification Mean saturation state with respect to aragonite in the oceans ≥80% of the pre-industrial level
Fresh water use Freshwater consumption ≤4000 km3/yr
Change in land-use Area of forested land as a percentage of original forest cover ≥ 75%
Novel entities NA NA
Atmospheric aerosol loading Aerosol optical depth NA
Regional limit of ≤0.25
  1. ppm: parts (of carbon dioxide) per million (parts of atmosphere)
  2. Radiative forcing: the change in energy flux in the atmosphere measured in Watts per square meter of Earth’s surface area (W/m2)
  3. E/MSY: extinct species per million species per year
  4. Saturation state with respect to aragonite is an indicator of ocean acidity
  5. Aerosol optical depth is a measure of the fraction of sunlight that is absorbed or reflected – a value of 0 indicates perfectly clear skies – a value of 1 indicates no sunlight penetration