Table 2 The ecological ceiling and its indicators of overshoot
From: Doughnut of social and planetary boundaries monitors a world out of balance
Dimension | Indicator (and planetary boundary) | Value (and % overshoot beyond boundary) | Historical trend | To eliminate overshoot by 2050 | |
|---|---|---|---|---|---|
2000–2001 | 2021–2022 | (%pt per year) | (%pt per year) | ||
Climate change | Atmospheric carbon dioxide concentration, parts per million (at most 350 ppm CO2) | 370 ppm (28%) | 416 ppm (94%) | +3.1** (worsening) | −3.4 |
Human-induced radiative forcing at the top of the atmosphere, Watt per square metre (at most 1 W m−2) | 1.8 W m−2 (78%) | 2.8 W m−2 (183%) | +5.5** (worsening) | −6.5 | |
Ocean acidification | Average saturation state of aragonite at the ocean surface (at least 80% of pre-industrial saturation state of 3.44 Ωarag) | 2.99 Ωarag (−34%) | 2.80 Ωarag (−6%) | +1.3** (worsening) | (within boundary) |
Chemical pollution | Production of hazardous chemicals, millions of tonnes per year (at most 5% of the 1,200 Mt of total chemicals produced in year 2000) | 933 Mt (1,455%) | 1,964 Mt (3,174%) | +81.8** (worsening) | −113 |
Nutrient pollution | Phosphorus applied to land as fertilizer, millions of tonnes per year (at most 6.2 Mt per year) | 14 Mt (123%) | 23 Mt (273%) | +7.1** (worsening) | −9.7 |
Nitrogen applied to land as fertilizer, millions of tonnes per year (at most 62 Mt per year) | 134 Mt (116%) | 193 Mt (212%) | +4.6** (worsening) | −7.6 | |
Air pollution | Asymmetry between Earth’s hemispheres of sunlight reaching the surface, owing to differences in atmospheric particle concentration (at most 0.1 inter-hemispheric difference in Aerosol Optical Depth) | 0.08 AOD (−29%) | 0.08 AOD (−29%) | – (not known) | (within boundary) |
Freshwater disruption | Proportion of land area with human-induced disturbance of blue-water flow deviating from Holocene variability (at most 10.2%) | 18.2% dev. (78%) | 18.2% dev. (78%) | – (not known) | −2.7 |
Proportion of land area with root-zone soil moisture deviating from Holocene variability (at most 11.1%) | 15.9% dev. (43%) | 19.3% dev. (74%) | +2.5** (worsening) | −2.6 | |
Land conversion | Area of forested land as a proportion of forest-covered land before human alteration (at least 75% of 64 million square kilometres) | 39 Mkm2 (55%) | 38 Mkm2 (61%) | +0.3** (worsening) | −2.2 |
Biodiversity breakdown | Rate of species extinctions per million species years (at most 10 E/MSY) | 100 E/MSY (900%) | 100 E/MSY (900%) | – (not known) | −32 |
Human appropriation of net primary productivity, billions of tonnes of carbon per year (at most 10% of 55.9 Gt C) | 15 Gt C (162%) | 17 Gt C (204%) | +2.0** (worsening) | −7.3 | |
Ozone-layer depletion | Concentration of ozone in the stratosphere, Dobson units (at most 5% decrease with respect to 1964–1980 value of 290 DU) | 283.0 DU (−50%) | 283.4 DU (−53%) | +0.1 (no change) | (within boundary) |
