Humanity’s greenhouse gas emissions may be acidifying the oceans at a faster rate than at any time in the last 300 million years. The sheer speed of change means we do not know how severe the consequences will be.
As well as warming the planet, carbon dioxide seeps into the oceans and forms carbonic acid. As a result the water becomes more acidic.
The pH is currently dropping by about 0.1 per century. This ocean acidification harms organisms such as corals that rely on dissolved carbonate to make their shells. It also disrupts behaviour in some animals.
Acidification is not the only threat to the oceans from greenhouse gases. Marine life also faces a threat from rising water temperatures and less dissolved oxygen.