O ne of the most sobering experiences of my professional life was working in the team in the 1980s which produced the Brundtland report, Our Common Future, for the UN secretary general. The report helped to define the concept of sustainable development, the recognition that economic growth (or development) has to be environmentally sustainable, respecting the importance of environmental limits and costs. It was sobering partly because it brought out clearly the nature of the threats; the scientific findings of global warming and climate change emerged from the Bellagio conclave at that time, and the scientific work on mass extinctions was solidifying.

It was also sobering because of the very different reactions of the representatives of rich and poor countries. While the former demanded a reversal of the fixation with economic growth and its environmental, resource-depleting, side effects, the latter wanted more growth in living standards to counter the environmentally negative effects of poverty: high birth rates, lack of facilities for sanitation, polluting forms of primitive energy like green wood and charcoal burning.