At last, the Sustainable Development Commission’s magnum opus has landed. Prosperity Without Growth? was launched on Monday, representing the culmination of five years’ work. Tim Jackson, the Economics Commissioner has produced an absolute ‘tour de force’. And there’s a lot riding on this for the Commission.

Way back in the mists of time, through the 70s and into the early 80s, there was an extremely lively debate about the compatibility between economic growth and big-picture resource and sustainability issues. Heavyweight economists batted academic papers back and forth; party political conferences formally debated the pros and cons of economic growth. All this was nicely stoked up by the two Opec-induced oil shocks and even the media were all over it.

Then oil prices came plunging back down, Jimmy Carter got stuffed by Ronald Reagan and free market fundamentalists began their long march through the knackered ranks of superannuated Keynesians.

The consequence of this has been that hardly any serious discussion about economic growth and sustainability has taken place since then. Unbelievable, in retrospect, as even a fool could tell you that if you continue to grow both the number of human beings and the volume of goods and services consumed by each of those human beings, on a planet with limited resources and stressed-out life support systems, then you are heading inevitably for a bust. Sooner or later.

Politicians of all persuasions have hugely enjoyed their 20-year leave of absence. But it’s an inexcusable dereliction of duty to go on avoiding this crunch point in the light of what’s been happening over the last few years – with oil going to $147 a barrel, food reserves at their lowest level for decades, chronic water shortages the world over, accelerating climate change and so on.

Paradoxically, the collapse in the global economy gives us some breathing space – but not much. If it’s back to business-as-usual, growth-at-all-costs as the sole route to progress, then biophysical reality will not long be delayed.

Politicians have got used to using one get-out clause in terms of avoiding any intellectual encounter with that crunch point: decoupling. Just decouple the benefits of economic growth from its costs (or externalities, as economists call them) through technology-driven resource efficiency, and all will be well.

If only. One of the toughest messages in Prosperity Without Growth? comes in Tim Jackson’s clinical critique of 'the myth of decoupling'. The reality is that even progress on relative decoupling (reduced environmental impact per unit of GDP) has been limited, whilst progress on absolute decoupling (reduced environmental impact full stop) which is what we have to achieve, has been non-existent.

That isn’t to deny the critical significance of decoupling. We desperately need far more of it than anything we’ve seen so far. Which means governments have got to do it, rather than just talk about it, even as they come to the inconvenient conclusion that it won’t be enough on its own.

Politicians may not want to hear these messages. But it’s our task to broadcast them much more loudly and much more clearly than we’ve done over the last 20 years. And Prosperity Without Growth? is what you need to make that happen.