It is estimated that by 2050, the global population will rise to 9.7 billion, from 7.7 billion in 2019.1 The global economy is expected to more than double over the same period.2 Urbanization, automation, and the rise of living standards will increase the demand for energy globally. More than half of the world’s population now lives in cities and towns, and the United Nations projects that the global urban population will increase to around 68% by 2050.3 If we continue with business as usual, this scale of expansion will accelerate climate change, and degrade the quality of air and water upon which all living organisms depend. To protect the environment without tempering economic growth, we need to redouble our commitment to reducing the consumption of energy and natural resources.