More frequent or intense floods, heatwaves, wildfires, droughts and typhoons devastate people’s homes, livelihoods and the natural world. A clean energy transition is urgently needed to reduce carbon emissions and prevent the impacts worsening. Wealthy countries have the prime historic responsibility for the climate crisis and therefore for its mitigation. But as the clean energy transition gathers speed, it inevitably also impacts lower-income, lower-emitting countries and communities. This research report, written by 20 co-authors from Africa, Asia, Latin America, the Middle East, the US and Europe, investigates the implications of the energy transition for them, and asks how the world can achieve a truly just, as well as fast, transition.