One of the great themes of the social debate about environmental protection has been the question whether environmental quality can be safeguarded without major economic or social change. With the advent of the notion of ‘sustainable development’ in the late 1980s a new consensus emerged which sug gested that the economy and the environment could be complementary, so long as the economy internalised the costs of damage to the environment and techno logical innovation provided for smarter and cleaner ways of doing things. Sustainable development rested on the argument that it would be possible, through the adjustment of incentives and the application of knowl edge, to reconcile increases in welfare with a healthy environment. This conviction grew out of the great successes achieved through environmental regulation, beginning in the 1960s, which had brought radical improvements in environmental quality — air, water and soil — in richer, industrialised countries. New tech nologies — less toxic products, more effi cient produc tion processes and a panoply of abatement techniques — modifi ed the environmental impact of social and eco nomic activities, while also enabling growing welfare. By adjusting the economic incentives of innovators in such a way that socially-desired trade-offs were made between economic and social welfare and environmen tal quality, growth and sustainability could be recon ciled — so the argument ran (cf. Elkington 1994).

But great themes don’t disappear; they lie dormant for a while, only to return in a different guise. Through the 1980s and 1990s it became increasingly clear that while many local and tangible environmental problems were being solved, new forms of environmental prob lems were emerging. These were being caused by the cumulative and global effects of social and economic activities, which — measured purely in terms of their energetic and material scale — were coming to have a major impact on biophysical systems. It had long been recognised that human activity has transformed land use and vegetation at the surface of the Earth (Clark et al. 1990), but it became apparent that the great biogeochem-ical cycles (such as the carbon, nitrogen, phosphorous and sulphur cycles) were also being profoundly modifi ed by industrial and agricultural activity (Schlesinger 1991; Ayres et al. 1994), with often poorly-understood conse quences for the functioning, dynamics and stability of atmospheric, hydrological and ecological systems.