As Lancet highlights, while coal is phased out of the energy system, in particular in electricity production, the rapid scaling up of zero-carbon energy production and use will be crucial. Critical renewable technologies for achieving this will be solar, wind and other safe renewable sources like geothermal. Solar is booming globally, as the Intertiol Energy Agency showed recently — a new era is upon us. The Lancet recognises that renewable energy continues to grow rapidly, mainly from increasing solar and wind investment, most notably in the US, Chi and Europe. A solar revolution is also under way in India.