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.