Studying the effect of acidic oceans on fish
27 March 2014 Last updated at 12:05 GMT
BBC Newsnight has seen a UN report due out on Monday, 31 March, saying there is conclusive proof that emissions of carbon dioxide (CO2) from modern society are turning the oceans more acidic.
It warns that a mass extinction of some species may be under way.
Around 24 million tonnes of CO2 from industrial society is absorbed into the sea every day, turning whole oceans more acidic.
Scientists are working to assess to effect the acid will have on sea life.
Dr Jodie Rummer, of James Cook University in Australia, explains how they measure the impact on fish.
Viewers in the UK can see more on this on Newsnight on Thursday, 27 March, at 2230 on BBC Two.