If we could trap the CO₂ we produce in the deepest depths of the ocean, where should we do it? Maybe not where scientists first thought, says Josie Robinson. She explores the theory behind ocean iron fertilisation in the Southern Ocean, and describes her work on testing it.

This week in the Planet Earth podcast, Jerry Blackford and Steve Widdicombe of the Plymouth Marine Laboratory talk about the world's first carbon capture and storage leakage experiment which looks at its effects on the marine environment.

Adding iron to the Southern Ocean may not have the climate benefits that advocates of geoengineering have hoped for, a new study suggests.

Using gypsum to neutralise the red mud released in a 2010 industrial disaster has also proved to be an effective way of absorbing carbon dioxide from the air.