The science of climate change predicts global warming of several degree Centigrade by 2100 if the CO2 level in the atmosphere continues to increase to double its pre-industrial level – and it is now going to be very difficult indeed to keep CO2 below that level. Moreover, the climate will continue to change for a long time after that, even if we manage to reduce greenhouse gas emissions, as the oceans only slowly absorb the CO2 from the air. The big picture is that while global total emissions eventually need to be reduced by at least a factor of 4, global population growth and industrial growth by the developing nations will mean that we probably need to reduce emissions per unit of GDP by a factor of forty. Can science and technology provide the solutions necessary for this kind of reduction? The low carbon energy technologies available to us can all contribute, but they are unlikely to be enough. CO2 capture and storage from power plants (CCS) and even perhaps from ambient air, in order to allow continued use of fossil fuels, is likely to be a vital development, and attempts to geo-engineer the climate are also conceivableâ€¦ However, some mix of education, economic incentives and regulation will be needed to make these developments happen, and happen soon.