Our tour of the food system has already taken us into some big environmental challenges. But before moving on to look at our energy supply we need to look at the climate emergency more broadly, along with a couple of other huge issues that get a quick nod here but really deserve whole books on their own.

The big picture on energy now and in the future. A tour of energy sources, the practicalities of transition, and the deeper underlying challenge for humans.

One billion reckless people would easily trash the place, while 15 billion careful people could snuggle up together and be fine. (Although, if everyone was careful there wouldn’t be 15 billion in the first place.)

Since so much of how humans do life is in need of rethinking, it is hardly surprising that as part of that we need to look again at the way we do business. This short chapter is not a comprehensive guide for business and technology in the Anthropocene but just has a few top-level thoughts, drawn partly from the evidence and logic of the book so far, and partly from 20 or more years consulting in organisations, including a few of the world’s technology giants.

This is a recent and huge change in the context in which we live. It demands a re-evaluation of how we operate. The Earth is no longer robust to our activities. Compared to us, the rest of the ecosystem gets more fragile by the day. Humans must learn how not to expand for the foreseeable future. We will not be doing significant space travel for a very long time so we have to make the most of Planet A – which luckily is still wonderful.

We’ve seen how it is physically possible to move quickly beyond fossil fuels and still have our energy needs met. We’ve seen how everyone can have a healthy diet while improving environmental dimensions of land and sea management. We’ve even seen how we can meet our transport needs at the same time. We’ve touched on biodiversity, disease risks and plastic pollution. All these challenges turn out to be happily solvable from a scientific and technical perspective.

After decades of asking politely and getting nowhere, we have a full-scale emergency on our hands. We have to have change. And it must be now. If the right kind of protest is what it takes, then that’s what we must have.

Almost every year since records began, our species has had more energy at its disposal than it had the year before. For the past 50 years, the growth rate has averaged 2.4% per year, more than tripling in total over that time. For the century before that it was more like 1% per year, and as we go back through history, the growth rate looks lower still but nevertheless positive, give or take the odd blip. We have been getting continually more powerful, not just by growing our energy supply, but by using it with ever more efficiency and inventiveness. In doing so, we have been increasingly affecting our world, through a mixture of accident and design. The restorative powers of our planet, meanwhile, have remained broadly the same, so the balance of power has been shifting – and it has now tipped. Throughout history, the dominant cultures have treated the planet as a big and robust place, compared to everything we could throw at it – and that approach has not, generally speaking, come back to bite us.