Marine scientists across the world are hunting for clues to one of the biggest environmental challenges facing our planet today – ocean acidification. For years we’ve known the ocean absorbs about a quarter of the carbon dioxide (CO2) in the atmosphere – but as carbon emissions continue to rise, the seawater chemistry is changing. And in increasingly acidic waters, marine animals can’t form the skeletons and shells vital for their survival. Thousands of species are in danger. Could acid oceans bring down entire ecosystems? With the clock ticking these marine scientists are facing the challenge of their careers. From the icy polar seas to the world’s most pristine coral reefs, ACID OCEAN tracks the latest in marine scientific research and meets an Australian scientist who has made a game-changing discovery. Nestled among Papua New Guinea’s stunning coral gardens, coral ecologist Dr Katharina Fabricius has found a unique reef, which opens a window to the future of our oceans. Will she uncover the secrets of the acid ocean?