It is increasingly becoming evident that man’s activities within the environment are far exceeding the sustainable capacity of the earth. In essence, the environmental load equals the size of the world’s population x the prosperity or welfare per head of population x the environmental use per unit of prosperity (welfare). It is now apparent that in 50 years’ time there will be an unavoidable requirement to reduce the environmental load 20-50 times. As it is doubtful that this can be achieved, we must either accept an increasing erosion of environmental values and standards worldwide or set about making processes more efficient by minimizing mass and energy flows. Time is running out!