This is an excerpt from a research article by Kathrine Richardson, et al, which was recently published in Science Advances Magazine. The entire article can be found here.
The transgression of a majority of Earth’s nine planetary boundaries (i.e., Climate change, Ocean acidification, Biosphere integrity, etc.), by human activities have now brought humanity well beyond a “safe operating space.”
This planetary boundaries framework update finds that six of the nine boundaries are transgressed, suggesting that Earth is now well outside of the safe operating space for humanity. Ocean acidification is close to being breached, while aerosol loading regionally exceeds the boundary. Stratospheric ozone levels have slightly recovered. The transgression level has increased for all boundaries earlier identified as overstepped. As primary production drives Earth system biosphere functions, human appropriation of net primary production is proposed as a control variable for functional biosphere integrity. This boundary is also transgressed. Earth system modeling of different levels of the transgression of the climate and land system change boundaries illustrates that these anthropogenic impacts on Earth system must be considered in a systemic context.
Fig. 1. Current status of control variables for all nine planetary boundaries.
Six of the nine boundaries are transgressed. In addition, ocean acidification is approaching its planetary boundary. The green zone is the safe operating space (below the boundary). Yellow to red represents the zone of increasing risk. Purple indicates the high-risk zone where interglacial Earth system conditions are transgressed with high confidence. Values for control variables are normalized so that the origin represents mean Holocene conditions and the planetary boundary (lower end of zone of increasing risk, dotted circle) lies at the same radius for all boundaries (except for the wedges representing green and blue water, see main text). Wedge lengths are scaled logarithmically. The upper edges of the wedges for the novel entities and the genetic diversity component of the biosphere integrity boundaries are blurred either because the upper end of the zone of increasing risk has not yet been quantitatively defined (novel entities) or because the current value is known only with great uncertainty (loss of genetic diversity). Both, however, are well outside of the safe operating space. Transgression of these boundaries reflects unprecedented human disruption of Earth system but is associated with large scientific uncertainties
Meanwhile, this update of the planetary boundaries framework may serve as a renewed wake-up call to humankind that Earth is in danger of leaving its Holocene-like state. It may also contribute to guiding the substantial human opportunities for sustainable development on our planet. Scientific insight into planetary boundaries does not limit, but stimulates, humankind to innovation toward a future in which Earth system stability is fundamentally preserved and safeguarded.
SCIENCE ADVANCES
13 Sep 2023
Vol 9, Issue 37