ABSTRACT
In the last century the global consumption of materials, energy and water and associated pollution has increased by several orders of magnitude. Many of the most pressing global sustainability problems are caused by the extraction and processing of resources and their discharge after use. The increase in atmospheric carbon dioxide (CO2) concentration contributing to global climate change is but one of the many consequences of human resource use. Humanity appropriates roughly 25 per cent of the biomass produced annually by green plants to provide food, feed and fibre. Human activities have doubled the amount of reactive nitrogen in the biosphere. Meanwhile, the amount of some metals accumulating in landfills and in-use stocks (e.g. buildings, infrastructure or machinery) has reached a size similar to that of known reserves.
