Doughnut Economics: Seven Ways to Think Like a 21st-Century Economist

by Kate Raworth

In 2009, an international group of Earth-system scientists, led by Johan Rockström and Will Steffen, took on this question and identified nine critical processes—such as the climate system and the freshwater cycle—that, together, regulate Earth’s ability to maintain Holocene-like conditions (all nine are described more fully in the Appendix). For each of these nine processes, they asked how much pressure it can take before the stability that has allowed humanity to thrive for thousands of years is put in jeopardy, tipping Earth into an unknown state in which novel and unexpected changes are likely to happen. The catch, of course, is that it is not possible to pinpoint exactly where danger lies and, given that many of the shifts could be irreversible, we’d be wise not to find out the hard way. So the scientists proposed a set of nine boundaries, like guard-rails, where they believe each danger zone begins—equivalent to placing warning signs upstream of a river’s treacherous but hidden waterfalls. What do those warning signs say? To avoid dangerous climate change, for example, keep the concentration of carbon dioxide in the atmosphere below 350 parts per million (ppm). In terms of limiting land conversion, ensure that at least 75 percent of once-forested land remains forested. And when it comes to using chemical fertilisers, add at most 62 million tonnes of nitrogen and 6 million tonnes of phosphorus to Earth’s soils each year. There are, of course, many uncertainties behind...