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

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

Earth system process	Control variable	Planetary Boundary
Climate change	Atmospheric concentration of carbon dioxide	≤ 350 ppm
Climate change	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
Nitrogen and phosphorus cycles	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
Atmospheric aerosol loading	Aerosol optical depth	Regional limit of ≤0.25

ppm: parts (of carbon dioxide) per million (parts of atmosphere)
Radiative forcing: the change in energy flux in the atmosphere measured in Watts per square meter of Earth’s surface area (W/m²)
E/MSY: extinct species per million species per year
Saturation state with respect to aragonite is an indicator of ocean acidity
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

ISSN: 2520-8748