Ecological sustainability is about having a viable material relationship between human and ecological systems. Life (nature’s economy) creates order using solar energy and photosynthesis to concentrate, structure and organise dispersed matter from the environment into plants, animals, mineral ore bodies, fossil fuel reserves, ecosystems and ultimately, the intricate web of living and non-living ecological relationships that constitutes the biosphere. Life (together with geological processes) makes matter useful and human economic systems survive by consuming useful matter or ‘usefulness’. The catch is that ‘usefulness’ is used up or degraded by modern economic activity.

Prior to the current industrial age, humans had a viable relationship with the global ecological system. Then human consumption of ‘usefulness’ increased exponentially as industrial production fuelled by vast stores of fossilised solar energy took off. Consequently, the ecological and material basis of our existence, which consists of ‘usefulness’, is disappearing.

Ecological sustainability requires humans to consume ‘usefulness’ no more quickly than nature’s economy produces it.