Integrated approaches across energy, water and environment systems can accelerate the process of mitigating climate change through urgent action. New scientific advances that extend multiple opportunities in this direction have emanated from the 2nd Latin American, 1st Asia Pacific, 4th South East European and 15th Conferences on Sustainable Development of Energy, Water and Environment Systems as represented in this editorial. The review of recent scientific advances connects the 27 research articles in this special issue with those of other researchers based on eight main themes. The first two themes relate to system flexibility for renewable energy penetration and urban solutions in the energy transition. The foci of these themes include enabling energy system flexibility, climate neutral islands, electrification solutions, optimizing urban energy systems, spatiotemporal modelling of heat demand and smart energy hubs. The next three themes relate to solar energy technologies, hydrokinetic, wind and osmotic innovations as well as bioenergy and combustion modelling. These themes include new advances for predicting and monitoring photovoltaic module performance, thermochemical energy storage for concentrated solar options, artificial intelligence for wind energy, micro-cogeneration, and waste-water utilization. The last three themes relate to batteries and hydrogen energy advances, including sector coupling opportunities, optimizing heat exchangers and networks as well as solutions for redesigning sectors and repurposing post-mining reservoirs for energy storage. There are multi-disciplinary interrelations among these themes and each contribution will support the wide-ranging opportunities for realizing the European Climate Law and any other similar targets around the world for sustaining planetary life-support systems on which sustainable development depends.