In the years since the first edition of Understanding Sustainable Development was written and published, quite a lot has happened. There have been a number of climate change conferences, the twentieth anniversary of the first Rio Earth Summit has been and gone, the impact of the financial crash of 2007–8 still rumbles on, a near-nuclear catastrophe occurred in Fukushima in Japan, and the Millennium Development Goals have been replaced by the Sustainable Development Goals (SDGs). We continue to witness increasingly extreme weather events, the ice cap at the North Pole is likely to disappear within fifteen to twenty years, the amount of carbon in the atmosphere grows inexorably, as does the global population in the innumerable towns and cities where most of us live. And not to forget that human beings share the planet with other creatures – the sixth mass extinction of these other creatures continues apace, too. The world is quickly changing and not exactly for the better. The planet’s ecosystems are more stressed than ever before and peak oil has led to the exploration of oil in regions that were once out of bounds, such as the Arctic, as well as a revival of interest in nuclear power, the rapid development of the fracking industry and the enlargement of the area devoted to extracting oil from tar sands in Canada. The geopolitical climate has altered too, not least with the clear emergence of China as probably the dominant economic, and maybe political, force of the twenty-first century, which seems to be becoming increasingly unstable in many areas. One thing, however, has not changed. We have now clearly and indubitably entered the Anthropocene and few people feel capable of denying that fact. Human actions have impacted seriously and negatively on our planet’s ecosystems and will continuously do so until we – that is, humanity – do something about it.