Very few people command as much respect in the highly disputatious world of climate change as Nick Stern – Lord Stern to me and you. His blockbuster Review in 2006 not only established the baseline for all subsequent economic analysis in this field, but also set him off on a decade’s worth of climate diplomacy all around the world.

So a new book from Nick Stern is a bit of a special moment for those of us keen to keep abreast of the key climate debates today – especially in the run-up to the international climate conference in Paris at the end of this year.

And Why Are We Waiting? does not disappoint. It’s an extraordinary book in so many ways – even though I have to own up to not being able to follow much of the more technical economic stuff, and was even a bit bowled over by his mind-bending excursion into the field of moral philosophy!

But that’s Nick Stern for you. He’s always argued that most economists engaged in the climate debate just don’t get far enough outside their own (often rather narrow) comfort zones; they’re only too happy “dodging the ethics”, as he puts it. He also covers the science (brilliantly), and explains in uncompromising terms why he now sees the risks of accelerating climate change as being so much worse than when he first laid them out back in 2006. Though this is a very positive book (in that he remains convinced that there is still time to get things sorted, and is hugely positive about the power of “technology plus good economics” to get us through to a world that has averted the threat of catastrophic climate meltdown), he is still prepared to present the risks of “business as usual” with chilling statistical rigour.

The simple truth is that Nick Stern is a wise, enlightened and progressive pragmatist. He knows how the world works. He has deep knowledge about China and India as well as about the European Union and the United States. He spells out the obvious (for instance, that solutions have to be both top-down and bottom-up; that markets alone cannot do the job; that the heavy political lifting has to be both national and international) in ways that may trouble the absolutists who fill so much of this political space. He has an inspiring commitment to social justice and more equitable solutions, but has no illusions about the gap between the kind of political leadership we need and the kind of political leadership we get.

Why Are We Waiting? is not an easy read – in all sorts of ways – so I rather doubt it will get to the top of David Cameron’s or George Osborne’s reading list. But that’s the tragedy of our times. Those who most urgently need (and would most benefit from) this kind of authoritative, impeccably rational thinking are the ones who are least likely to seek it out. But no one’s done more to try and overcome those barriers than Nick Stern.

Jonathon Porritt is Founder Director of Forum for the Future. His most recent book, The World We Made: Alex McKay’s Story from 2050, is published by Phaidon. www.forumforthefuture.org