physical capitalcould substitute for labour, particularly skilled labour. The use of drastically undervalued nature, therefore, was economic not simply in providing a subsidy to the market economy, but also in keeping down labour costs and keeping organized labour under control. (I will look more closely at the implications of this relationship to labour in the next section.) For millennia the human economy remained quite small relative to the scale of the planets ecosystems. Today, however, the very scale of the economy means that we can no longer ignore externalized costs. Such costs reflect new forms of pollution and environmental destruction that threaten not just local environments, but the integrity and balance of the entire planets biosphere. Previously, local or regional communities may have been threatened, but today the scale of destruction threatens the survival of the entire human species. It is not only that many of natures materials are becoming scarcerequiring ever more destruction to extract thembut the biological sinks that have absorbed industrial waste are increasingly incapable of functioning any longer. Many of ecosystem servicesincluding pure air and water and the absorption of humanitys wastecan no longer be taken for granted, since they are not only valuable, but irreplaceable.