While the UN was discussing climate change at the General Assembly, a new report showed that seven out of nine critical limits for Earth’s health have now been passed.
Bleached staghorn coral in the Great Barrier Reef | Credit: Matt Kieffer/Creative Commons
The Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research revealed that last year, ocean acidification had breached a boundary for the first time. The increasing acidity of the ocean is caused by the absorption of excess CO2 from the atmosphere, which they said was driven mainly by burning fossil fuels made worse by deforestation.
Acidification makes it harder for organisms like oysters and corals to build their shells or skeletons, disrupting marine ecosystems and potentially affecting food security and coastal protection. Corals, both in cold water and in the tropics are at risk, as are Arctic environments.
Currently, the institute says there are only two planetary boundaries that are within safe limits—air pollutants and the ozone layer in the stratosphere—successes they attribute to international action on aerosol emissions, although parts of the world, such as South and East Asia, and parts of Africa and Latin America, are still experiencing dangerous particulate pollution.
The other boundaries that have been breached are climate shifts in temperature and weather patterns, changes in land systems like deforestation, freshwater use, biosphere functioning and resilience, biogeochemical flows such as water or nitrogen cycles, and novel entities like chemicals and microplastics.
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