‘Ticking timebomb’: sea acidity has reached critical levels, threatening entire ecosystems – study

Ocean acidification has already crossed a crucial threshold for planetary health, scientists say in unexpected finding

• More on this story: How the evil twin' of the climate crisis is threatening our oceans

The world's oceans are in worse health than realised, scientists have said today, as they warn that a key measurement shows we are running out of time" to protect marine ecosystems.

Ocean acidification, often called the evil twin" of the climate crisis, is caused when carbon dioxide is rapidly absorbed by the ocean, where it reacts with water molecules leading to a fall in the pH level of the seawater. It damages coral reefs and other ocean habitats and, in extreme cases, can dissolve the shells of marine creatures.