1105. Quantifying Earth-System Boundaries

The planetary boundaries were proposed in 2009 (Rockström et al. 2009). Then, in 2023, the concept of "safe and just Earth-system boundaries (ESBs)" was also proposed (Rockström et al. 2023). Today, in relation to these, I would like to introduce the latest report by the Earth Commission of the Lancet Planetary Health, published in the Lancet Planetary Health journal (Gupta et al. 2024). Rockström is also listed as a co-author in this report.

The health of the planet and its people is at risk. The committee quantified "safe and just ESBs" and made an assessment based on them.

"Safe" means that biophysical stability can be maintained and strengthened over the long term, but if that is not the case, the Earth will be at risk. "Just" means that the risk of serious damage to current and future generations, countries, and communities can be minimized, but if that is not the case, people will be at risk. The more stringent of the two criteria, safe and just ESBs, is defined.

The committee also defines a "minimum access level" that is assumed to give everyone minimum access to food, water, energy, and infrastructure. The area between the ESBs and the minimum access level is called a "safe and just corridor." If the minimum access level exceeds the ESBs, the corridor itself does not exist. The ideal situation would be for the world to be within this corridor. It is necessary to enter the corridor, but it is also important that resources are distributed fairly within the corridor.

Eight ESBs have been defined for five domains: biosphere (functional integrity and natural ecosystem area), climate, nutrient cycles (phosphorus and nitrogen), freshwater (surface and ground), and aerosols. Seven of them are already exceeding their limits: functional integrity, natural ecosystem area, climate, phosphorus, nitrogen, surface water, and groundwater. The eighth, air pollution, is exceeding its limits at the local level in many places.

Modeling results show that without social change and redistribution of natural resource use, those who currently do not reach the minimum level will place pressure on the Earth system. It is also predicted that the climate ESBs will not be achieved by 2050, even if everyone in the world lives at the minimum, unless there is a transformation of the energy and food systems. Therefore, a safe and just corridor cannot be achieved without fundamental social change and technological change. Moreover, systemic changes that will lead humanity to a safe and just corridor will include reduction and reallocation of consumption, and changes to the economic system, technology, and governance.

Reference: 
Gupta, Joyeeta, et al. "A just world on a safe planet: a Lancet Planetary Health–Earth Commission report on Earth-system boundaries, translations, and transformations." The Lancet Planetary Health (2024). https://doi.org/10.1016/S2542-5196(24)00042-1
Rockström, J., Steffen, W., Noone, K. et al. A safe operating space for humanity. Nature 461, 472–475 (2009). https://doi.org/10.1038/461472a
Rockström, J., Gupta, J., Qin, D. et al. Safe and just Earth system boundaries. Nature 619, 102–111 (2023). https://doi.org/10.1038/s41586-023-06083-8

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