Read extracts of the interview below.

In the five years since his appointment as Archbishop of Canterbury, Rowan Williams has shown ample signs of turbulence.

He has spoken out on everything from carrier bags to climate change, and of the "real possibility of social collapse" if we don't address the environmental crisis. It could mean "not only spiralling poverty and mortality, [but] brutal and uncontainable conflict... An economics that ignores environmental degradation invites social degradation – in plain terms, violence".

He has called for deep cuts in carbon emissions on the basis of 'contraction and convergence'. (This is the quiet revolutionary in the ranks of climate change strategies, aiming at equal per capita emissions for all, meaning huge reductions for the rich countries.)

He's happy to take on economic theory, insisting that it "cannot be separated from ecology... Ecological fallout from economic development is in no way an 'externality' as the jargon has it: it is a positive depletion of real wealth, of human and natural capital. To seek to have economy without ecology is to try to...formulate human laws in abstraction from...the laws of nature."

Williams clearly doesn't shy away from an intellectual tone – even if at times it might dilute the message somewhat. (One of his addresses to the Lambeth Conference of Bishops was famously described as "the most erudite, though the least understood".) And he's keen to link a healthy environment with a healthy soul. "If we live in a context where we construct everything, from computers to buildings to relationships, on the assumption that they'll need to be replaced before long – what have we lost?"

I meet him in a building that's lasted centuries. Lambeth Palace, to be precise, home to Archbishops since the 13th century. Step through the old wooden door in the gateway, and it's a bit like going through Platform 9 ¾ to Hogwarts: you're suddenly a world away from the rush and roar of the 21st century. Here, it's all honey-coloured stone, quiet courtyards and wide sweeps of landscaped lawns bathed in spring sunshine. There's something collegiate about it, a place fit for contemplation. If you wanted a visible antithesis of 'social collapse', you couldn't find better.

The academic air persists inside the archiepiscopal study, which, with its leaded windows, fireplace and comfy leather armchairs, could be home to an Oxford don. Appropriate enough, in this case, as Williams was professor of theology at Oxford until 1992 (and you can't help wondering if, on occasion, he wishes he still was...).

And it's there when I ask what first triggered his passion for green causes

"I was just finishing my doctorate studies, [which focused] on eastern Christian theology; Greek and Russian. And one of the writers I was studying at that time, Yannaras, was already writing in Greek journals about the environmental crisis as a Christian issue... I remember translating one or two of his shorter pieces into English and feeling this was really something I needed to get my mind around and my practice around...".

It's a characteristically studious response: one which chimes with those who see him as academic in not such a good way; an out of touch way. He has talked before of wanting "to get people to see that living in balance, living in rhythm, living according to some sort of... inner harmony, is actually a recipe for being more human rather than less."

But it's one thing to contemplate inner harmony in the civil surroundings of the palace: how does it play in Lambeth's rougher council estates a mile down the road?

"Well, I think a lot of people living in those environments are acutely conscious of their surroundings. And you want to say to them: 'Do you want a safe environment, do you want an environment that feels human...do you think you deserve better? And what can you do practically to make this look like a place where people are taken seriously, because in such a setting you are on the receiving end of quite a lot of rubbish, of every sense, thrown at you by society.'"

"Actually, environmental work in that setting is a political gesture. A couple of years ago, we had a team of Christian youngsters – A Soul in the City – doing a lot of environmental projects around inner London, in collaboration with local communities like this, and that was the message, really – you deserve better."

He's wary of "getting too specific" on particular policies – "I can so easily sound nannyish when I start going on about speed limits", for example - but says he'll "keep pressing for" tougher targets on carbon cuts. And he cites the active involvement of the Bishops of London and Liverpool in particular, in climate change debates in the Lords.

If you're outside the Church, it's easy to forget just how many feathers can still be ruffled by such talk. Williams admits that "I've rather got into trouble for saying that [the environmental crisis] is the major moral issue that confronts us." But he senses the ground shifting. "The notion that there is absolutely nothing distinctively Christian about caring for the environment is pretty much a minority position now. It's [mainly occupied] by only the very extreme bits of American evangelicalism, who would say that the earth's going to end quite soon anyway so why bother?!"

They're not ecstatic about his enthusiasm for interfaith dialogue, either, but he's adamant that "this is not an issue that any one faith can tackle alone". He's chair of 'Building Bridges', an annual Christian-Muslim seminar, which has a strong environmental focus, and climate change is near the top of the agenda of wider ecumenical meetings involving representatives from Jewish, Buddhist and Hindu faiths, among others.

So does he feel he's making a difference? "I don't know. There are lots of voices, and I couldn't claim that mine has any more impact than anyone else's." He's aware of the dangers of sounding "like a crank with ideas". Does he think people are put off by his sermonising? "It doesn't bother me that much. In a sense an Archbishop is set up for it. You expect people to moan about sermonising, but that is what you are paid to do! The challenge is, how do you stop it being just sermonising? How does what you say have any kind of credibility?"

Part of his answer lies in initiatives like 'Shrinking the Footprint', where the Church has committed to cutting carbon by 60%. This year's Lambeth Conference will feature 'voices of the vulnerable' – contributions from people already being affected by rising seas in places like the Pacific and Bangladesh. All emissions associated with the conference will be offset through forest projects in Burundi.

Climate-proofing the Church's substantial investments will be a much tougher nut to crack, Williams acknowledges, but he points to an ethical working group that's developing "preferential attitudes to environmentally responsible investment".

So what about the great green sin of flying? "This year I'm trying to take a rather more radical approach to my own air travel. The only fixed [flight] this year is a trip to Auschwitz. After that I'm looking at travelling by train in Europe, and not going further afield, and just seeing what that feels like and what issues it raises." Meanwhile, he has bought a hybrid car, and is encouraging episcopal colleagues to do likewise.

What about cycling? "I can't cycle – I keep falling off. I have a deaf ear, so my sense of balance is hopeless, I'm afraid."

© Green Futures Magazine