A new international report "An updated synthesis of the impacts of ocean acidification on marine biodiversity" shows beyond doubt that ocean acidification is an issue of serious environmental and policy concern. This timely synthesis has considered the impacts of ocean acidification across many levels of biodiversity, and as such represents an important resource for considering the future of our ocean explains Dr. Salvatore Arico, who acts as the principal focal point on biodiversity science and policy at UNESCO. As carbon dioxide in the atmosphere goes up (and there was a record-breaking increase in 2013), the pH of the ocean falls. That chemical response is unavoidable; what has been less certain is whether marine life will be affected. Ten years ago, only a handful of researchers were investigating the biological impacts of ocean acidification: whilst their results gave cause for concern, it was clear that a lot more measurements and experiments were needed. Around a thousand published studies later, it has now been established that many marine species will suffer in a high CO2 world, with consequences for human society.