If we want to avoid the climate catastrophe that awaits us, then we need to urgently cut planetary CO2 emissions by half. This is the absolute minimum. Unfortunately the experts are predicting that global energy consumption will double between now and the year 2050. And so we need to square the circle… Reasonable energy consumption is the only solution that is realistic, reasonable, and sustainable. This revolution in social and economic behaviour, including individuals, will affect all areas including consumption, agriculture, transportation, homes, urbanism, and leisure.