When the first post-growth thinkers began to formulate the possibility of a steady state economy, it was in response to future scenarios. The famous report The Limits to Growthexplores some of these scenarios, predicting an eventual peak and decline of industrialisation. At the time, these were speculative, projections and extrapolations. They were warnings: if current trends continued, we’d hit the natural limits of the biosphere, and new economic perspectives were needed to avert that inevitable outcome.

Economics without growth has returned to the agenda more recently. Thirty or forty years on, it’s no longer speculative. We’re not talking about future scenarios, we’re talking about the visible realities of price spikes, shortages, a destabilising climate and a global economy on a knife edge. Look back at those graphs in The Limits to Growth, and you’ll see the forecasted peaking of industrial society falls right about now.

The word ‘unsustainable’ is itself future facing, denoting the impossibility of sustaining something in the longer term. At some point, the practice in question must therefore move from being unsustainable to being unsustained. So Richard Heinberg is calling it: this is that moment. We were warned that sooner or later we’d hit the limits to growth, and now we have. The warnings, he argues, were “a message appropriate to the 1970s and 80s. We didn’t change direction then, and now we are nearing or at the point of declining energy, declining freshwater, declining minerals, declining biodiversity… and a declining economy.”

Heinberg made his name as a peak oil communicator, but peak oil only gets a short section here. The killer factor that makes this the beginning of the end for economic growth is debt. The cheap energy of fossil fuels has driven growth economic growth for over a century, but it is the debts that we’ve run up in the latter decades that make future growth impossible. The US spends 20% of tax revenues just paying off the interest on its debts. Millions of American homes are underwater, consumer credit the millstone around our necks. Having piled billions into bailouts and stimulus packages, there’s nothing left in the kitty to handle the transition that climate change and resource depletion requires.

And that means that growth is pretty much over. There will still be growth, a year here, a quarter there, but sustained long term growth isn’t possible under current circumstances. It relied on debt and fossil fuels, and we can’t secure enough of either to continue. Instead, we need to focus on making the transition to a post-growth economy, that is re-localised, resilient, and that serves human needs.

Needless to say, this is not a popular message. Even now reviewers will be sharpening their quills in readiness to tear Heinberg’s argument apart. It’s a matter of principle. To say that growth isn’t possible, or isn’t desirable, is a matter of economic excommunication. (As Tim Jackson says, politicians “physically recoil” when he tells them the title of his book, Prosperity without Growth.) But that doesn’t mean Heinberg is wrong, and the book deals with all the obvious ripostes (efficiency, decoupling, innovation, etc).

If you’ve been following the post-growth conversation, this book is a must read, putting the economic and environmental limits together to suggest that ‘peak debt’ is just as much a threat as peak oil. If you’re new to post-growth economics, it’s not a bad place to start either. It is meticulously researched and well argued, if a little technical in places. It is bold, wise, and profoundly counter-cultural. Yes, it’s gloomy, but it’s also full of ideas for making things better, and people and movements already headed in the right direction. The End of Growth is likely to be the most hated and ridiculed economics book of the year, but the chances are it’s the most important too.