Figure 1 Adapted from Rockstrom et al 2009

At the time of writing we are awaiting the outcome of the Climate Change COP27 talks in Sharm el Sheik, Egypt. Looking back at a 2009 scientific paper outlining a safe operating space for humanity¹ and introducing the concept of “Planetary Boundaries), showed that 3 of the 9 boundaries were already being exceeded and were thus endangering the Earth’s system (figure 1), and continue to deteriorate.
COP 27 is primarily concerned with climate change and attempting to obtain agreement to lower anthropogenic greenhouse gas emissions which cause it; however, we should not just consider carbon emissions as the sole threat to the planet.

Considering Rockström’s 9 boundaries and briefly looking at the current situation. It should be recognised that Rockström’s 9 boundaries are irrevocably interlinked: i.e. CO² causes climate change but also acidification in the ocean; artificial nitrogen fixation during fertiliser production causes increased nitrogen levels in the ocean which adversely affects biodiversity – it also leads to increased levels of N²O, a “greenhouse” gas which also depletes the ozone layer. A picture emerges that is not reassuring with probable deterioration in all the boundaries but one.

1. The safe boundary for climate change, indicated by the concentration of atmospheric carbon dioxide, is proposed to be 350 ppm compared to a preindustrial level of 280, which would limit the subsequent global rise in temperature to about 1½ °C.² In 2009 the measured level was 387. The current level is 415.7 ppm³ which is 149 per cent of the pre-industrial levels and will give rise to a global increase of temperature of about 2.6°C – with all the dangers inherent in the subsequent extremes of climate produced⁴.

2. The safe rate of Biodiversity loss as represented as the extinction rate (number of species per million species per year, E/MSY) is 10 compared to a preindustrial level of 0.1 -1. In 2009 it was greater than 100 – it may now be 150–260 E/MSY ⁵

3. The 3rd exceeded boundary (Nitrogen/Phosphorous fertiliser production) was estimated to be 121 million tonnes per year in 2009 compared to a boundary limit of 35. In the early 2000’s, the production of nitrogen fertilizers stood at some 95 million metric tons. By 2020, this figure had increased to over 123 million tons. Production of phosphate fertilizers also increased, growing by roughly 18.6 percent ⁶.

4. Ocean acidification: The predicted pH decrease of approximately 0.3 units during the 21st century would be a greater change than possibly at any time in the last 300 million years⁷ .

5. Global Freshwater use: Water use has been increasing worldwide by about 1% per year since the 1980s and is expected to increase by 20% to 30% until 2050. The increase is mainly occurring in developing countries and emerging economies. It is currently approximately 4000km⁸.

6. Change in land use: It is estimated that land use change has affected almost a third (32%) of the global land area in just six decades (1960-2019) and, thus, is around four times greater in extent than previously estimated from long-term land change assessments⁹.

7. The damage from aerosols can be great, but their highly variable impacts left Rockström’s team unable to put a number on safe limits¹⁰.

8. Chemical pollution: The chemical pollution boundary has been expanded and renamed “novel entities” created entirely by us humans. They include emissions of toxic compounds such as synthetic organic pollutants and radioactive materials, but also genetically modified organisms, nanomaterials, and micro-plastics. These can persist in the environment for a very long time, and their effects are potentially irreversible¹¹.

9. At last some Good News! Stratospheric ozone depletion and the ozone hole have generated worldwide concerns. These concerns led to the adoption of the Montreal Protocol in 1987, which bans the production of CFCs, halons, and other ozone-depleting chemicals. Recovery is projected throughout this century, and the ozone hole is expected to reach pre-1980 levels by around 2075. The Montreal Protocol is considered the most successful international environmental agreement to date¹².

Returning to the subject of COP 27, the UN is the only global organisation we have capable of producing an agreed plan of action, although much of the output from the COP series of meetings until now has been well intentioned – but inadequate. My personal belief is that nothing effective will be done until we cross a tipping point whereby something truly dreadful happens. One might have thought that the recent increase in catastrophic fires, tropical storms, floods, heatwaves, cold spells, etc. would prove that urgent action was needed now.

Individually we should continue to do all can to reduce our own carbon footprints; it is however, only by government action that the planet can be saved; the success of the Montreal Protocol in repairing the holes in the ozone layer does show that united action by the world’s nations can bring about a change in behaviour resulting in a planet that is not wrecked for future generations.

¹ Rockström. J. et al, 2009. A safe operating space for humanity. Nature, 461, 472 – 475.

² Rockström. J. et al, 2009. A safe operating space for humanity. Nature, 461, 472 – 475.

³ United Nations. 2022. UN News:Climate change: CO2 and methane in our atmosphere reach record levels. New York. United Nations. Available from: https://news.un.org/en/story/2022/10/1129887

⁴ Climate Action Tracker. 2022. Temperatures. Climate Action Tracker. https://climateactiontracker.org/global/temperatures/ [Accessed 21 November 2022].

⁵ Robert H. Cowie, R.H., Boucher, P,. Fontaine. B,. 2022. The Sixth Mass Extinction: fact, fiction or speculation? Biological Reviews 97. 640–663. Cambridge: Cambridge Philosophical Society.

⁶ Fernández, L., 2022. Global fertilizer production 2005-2020, by nutrient. Statista. Available from: https://www.statista.com/statistics/1290786/global-fertilizer-production-by-nutrient/ [Accessed 19 November 2022]

⁷ 2015. Ocean Acidification: Saturation State. National Oceanic and Atmospheric Administration U.S. Department of Commerce. Available from: https://sos.noaa.gov/catalog/datasets/ocean-acidification-saturation-state/[Accessed 19 November 2022]

⁸ The Global Education Project. Fresh Water Available from: https://www.theglobaleducationproject.org/earth/fresh-water#global-fresh-water-use-1901-2014 [Visited 21 November 2022]

⁹ Pearce. F,.2010. Earth’s nine life-support systems: Aerosol loading. New Scientist. Obtainable from: https://www.newscientist.com/article/dn18578-earths-nine-life-support-systems-loading. [Accessed 19 November 2022]

¹⁰ Pearce. F,.2010. Earth’s nine life-support systems: Aerosol loading. New Scientist. Obtainable from: https://www.newscientist.com/article/dn18578-earths-nine-life-support-systems-loading. [Accessed 19 November 2022].

¹¹ The Anthropocene. 2022. Planetary Boundaries. Available from: https://www.anthropocene.info/planetary-boundaries.php. Visited 21 November 2022]

¹² UN Environment Programme. About Montreal Protocol. New York. UNEP
https://www.unep.org/ozonaction/who-we-are/about-montreal-protocol. [Accessed 21 November 2022].