Technological change has played a central role in historical transitions, and is expected to remain central to a future transition to global environmental sustainability. Technology can be conceived as the art of the science of the possible. It is art in being founded in human creativity and ingenuity. Historical analysis of technological change increasingly emphasizes the indispensability of a wide range of actors and institutions. Technology is science in its more obvious applications as hardware and devices wrought through lengthy periods of research, development, testing and learning. It also lends itself to scientific assessment, although it is important that this integrates rather than ‘holding constant’ the human dimension. An innovation systems framework developed as part of the Global Energy Assessment illustrates how the roles of actors, institutions, resources, and knowledge generation can be integrated with conventional technological development processes. Applying this framework to examine current innovation efforts for climate change mitigation reveals a marked asymmetry. Innovation inputs strongly favour large-scale energy supply technologies. But actual and required innovation outputs are weighted towards dispersed energy end-use technologies in which people are so much more central. This sets a challenge for the possibility space for future technological change. Scenario assessments as well as innovation efforts need rebalancing in favour of people.