Geoengineering the climate: Science, Governance and Uncertainty: The Royal Society Study - John Shepherd (NOCS). The climate change we are experiencing now is caused by an increase in greenhouse gases due to human activities, including burning fossil fuels, agriculture and deforestation. There is now widespread belief that a global warming of greater than 2C above pre-industrial levels would be dangerous and should therefore be avoided. However, despite growing concerns over climate change, global CO2 emissions have continued to climb. This has led some to suggest more radical 'Geoengineering' alternatives to conventional mitigation via reductions in CO2 emissions. Geoengineering is deliberate intervention in the climate system to counteract man-made global warming. There are two main classes of geoengineering; direct carbon dioxide removal, and solar radiation management, which aims to cool the planet by reflecting more sunlight out to space. This talk will summarise the findings of a recent review of Geoengineering carried-out by the UK Royal Society discussing the climate effects, costs, risks, and research and governance needs for each approach.