The global indicator for ocean acidification, the aragonite saturation state, has worsened and is very close to exceeding the safety threshold
Living Outside the “Safe Space” of the Last 10,000 Years
We have likely already exceeded 7 out of 9 planetary boundaries – one more than the last “check-up” of the Earth. Thus, we are largely living outside the “safe operating space” in which humanity can thrive while keeping the planet stable and resilient.
This is the warning contained in the Planetary Health Check report, a new framework for monitoring the limits of the Earth system developed by scientist Johan Rockström. The publication will be annual and will focus on the interdependence among various boundaries and the achievement of certain tipping points.
“Once a boundary is exceeded, the risk of permanently damaging the Earth’s vital support functions increases, as does the likelihood of triggering tipping points that lead to irreversible changes. If multiple boundaries are violated, the risks increase significantly,” explain the authors of the report.
Planetary Boundaries: Alert for Ocean Acidification
In the latest update, ocean acidification has come under the spotlight. This process damages calcifying organisms, negatively impacts marine ecosystems, and reduces the ocean’s efficiency in functioning as a carbon sink. The indicator used to assess this phenomenon – the aragonite saturation state – has dropped to 2.8. The threshold not to be exceeded is 2.75, and it is “close to exceeding the limit.”
The map of changes in ocean pH from 1980 to 2022 shows that there is virtually no corner of the planet recording an improvement. Ocean acidification is affecting oceans worldwide, with “more pronounced effects in the Southern Ocean and the Arctic Ocean,” the report states. Some areas “have already become undersaturated concerning aragonite,” posing real risks to vulnerable calcifying organisms that play an important role in the food web.
The Other Planetary Limits
All indicators related to the 6 planetary boundaries that had already been exceeded are worsening. These include:
- Climate change
- Introduction of new entities
- Change in biosphere integrity
- Modification of biogeochemical flows
- Change in the Earth system
- Change in freshwater systems
The first four limits are now in a zone considered “high risk,” while the last two have been exceeded but with a smaller margin.
Meanwhile, the indicator for stratospheric ozone depletion remains stable, and there has been a slight improvement in atmospheric aerosol loading.
