As CO2 levels rise in seawater, they make the chemical formation of calcium carbonate very difficult, affecting everything from tiny Antarctic pteropods to massive boulder corals on the Great Barrier Reef.
The waste CO2 being pumped out by human civilisation isn’t only responsible for causing climate change as it builds up in the atmosphere. In the centuries since the Industrial Revolution, it has also been quietly dissolving into Earth’s oceans, and very gradually increasing their levels of acidity.
In this way, the oceans have helped mitigate the effects of greenhouse gases, absorbing about 25% of the excess CO2 produced in the past two centuries. But this buffering effect comes at a price.
“By absorbing around a quarter of the total human production of CO2, the ocean has substantively slowed climate change. But it also has less desirable consequences, since the dissolved CO2 affects seawater chemistry, with a succession of potentially adverse impacts,” notes a 2014 United Nations report.