Report on planetary health: soon seven out of nine borders crossed
The Earth has already crossed six out of nine planetary boundaries. According to climate impact researchers, a seventh boundary is about to be crossed.
The effects of ocean acidification are apparently most noticeable in the Arctic and Antarctic.
(Image: Michal Balada/Shutterstock.com)
On Tuesday, the results of the first Planetary Health Check, or PHC for short, were published by the Planetary Boundaries Science initiative. The report, which was compiled under the leadership of the Potsdam Institute for Climate Impact Research, publishes conclusions about the health of the Earth based on the planetary boundaries. It shows that six out of nine planetary boundaries have already been exceeded and by how far. A seventh exceedance of defined threshold values is apparently imminent: ocean acidification is close to the critical threshold value.
Acidification refers to a drop in the pH value of the oceans. Acidification is triggered by the increased absorption of COâ‚‚ from the atmosphere. Acidification harms calcifying organisms such as corals, plankton, snails, mussels and sea urchins and threatens the marine food web. It also reduces the oceans' ability to absorb COâ‚‚. According to the report, the effects are most noticeable in the Antarctic and Arctic.
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Although the degree of acidification is currently still just within the range defined as safe, the indicator for acidification, the aragonite saturation state, is approaching the critical limit, according to the report. New studies indicate that even current levels can be problematic for marine organisms, making a reassessment of the safe limit necessary.
Four out of nine critical Earth system processes in high-risk zones
The nine boundaries outline humanity's safe operating space for a stable and resilient planet. They relate to nine critical Earth system processes that affect life-support systems on Earth. These include climate change, overloading with novel substances, depletion of the ozone layer in the stratosphere, aerosol pollution of the atmosphere, acidification of the oceans, disruption of biogeochemical cycles, changes in freshwater systems, changes in land use and changes in the integrity of the biosphere. If a threshold is exceeded, the risk increases that tipping points will be crossed, meaning that the Earth will be irreversibly damaged in one of these areas.
Thresholds have already been exceeded in the case of climate change, the introduction of new entities and changes to the integrity of the biosphere and biogeochemical fluxes. All four areas are already in high-risk zones. To a lesser extent, the limits have been exceeded in the areas of land system change and freshwater. Ozone depletion in the stratosphere has apparently remained stable. According to the report, there has even been a slight improvement in atmospheric aerosol pollution.
(kst)
