The Ocean Acidification Symposium was presented by the Centre for Chemical and Physical Oceanography, in November of 2012. The day-long symposium featured brief presentations from a wide range of researchers, of which this is one: Professor Phil Boyd discusses large scale geo-engineering projects that may mitigate climate change. There are two basic forms of mitigation plans - Solar Radiation management, or carbon dioxide removal. Professor Boyd explores ways to assess the usefulness of different approaches.