For every calorie of food produced by agriculture, 10 calories of fossil fuel is burned. And today Bush announces the intention to cut US petroleum consumption by 20% in ten years - mainly through substituting corn-derived ethanol. The corn required to fill an SUV tank with bioethanol just once could feed one person for an entire year. Lester Brown has described the boom in bioethanol as a competition between the 800 million people in the world who own cars with the 3 billion people who struggle to feed themselves on less than $2 a day. This year’s Soil Association conference is on the theme of “Preparing for a post-peak oil food and farming future,” with keynote speakers from the peak oil fraternity, Colin Campbell, Richard Heinberg, Jeremy Leggett and Rob Hopkins. Jonathon Porritt, no less, (another speaker) had an piece in the Guardian today bylined “Declining oil reserves will impact hugely on energy prices and the way we eat and farm.” He points out that the idea that the UK might be forced back on predominantly its own productive resources is dismissed as “retro-protectionist rambling.” I predict the term “deglobalisation” will mainstream in the not too distant future. Let’s hope this comes about through reasoned response to the unfolding crisis rather than in shocked post-hoc analyses following a successful attack of the Saudi Abqaiq facility or a tanker in the Straits of Malacca. Jonathon Porritt’s article…Banana drama

Declining oil reserves will impact hugely on energy prices and the way we eat and farm. Is Britain ready for a new agri-culture?

In a recent interview in the Sunday Times, the environment secretary, David Miliband, let it be known that he sees the choice between conventional and organic produce as a matter of “lifestyle”. No, actually. Whatever you may feel about the benefits of organic from a taste, nutritional or wider health point of view - which may just about be described as lifestyle issues - the climate change “gain” of buying organic is all but indisputable. By virtue of organic farmers not using nitrogen-based fertilisers or carbon-intensive chemicals, the amount of “embedded CO2″ in a kilo of organic product will be significantly less than the non-organic equivalent.

That’s not to say that organic farmers do not share an equal responsibility for all the carbon emitted in moving their produce around the place, especially when it is air-freighted from far-flung destinations cashing in on our growing hunger for organics wherever they’re grown. That’s what makes the recent M&S decisions to label all air-freighted produce - whether organic or not - particularly interesting, on top of its commitment to source seasonal organic produce only from growers in Britain and Ireland.

And with the competition now on to see which of our retailers will be the first to label some of their key food products with details of how much CO2 it takes to get it on to your plate, the idea of carbon as a “parallel currency” to money is beginning to look a great deal more serious than it did even a year ago. That’s certainly part of Miliband’s longer-term thinking, as he keeps pushing people in the direction of tradeable carbon allowances, bringing the idea of carbon trading right down to the individual level.

However, it is by no means certain that this kind of “carbon literacy” has as yet taken root in every nook and crevice of the Department for Environment, Food and Rural Affairs (Defra). Post-Stern, the department’s passionate advocacy of the benefits to UK consumers of an increasingly globalised food economy remains undiminished. Simple projections demonstrating what might happen to global supply chains if both the price of oil and/or the price of carbon took off over the next 10 years are hard to come by. Little serious attention is being paid to the hypothesis that supplies of oil may well peak over the next few years, rather than “around 2030″, which is the reassuring message the oil companies would have you believe. With the world economy continuing to boom, that “peak oil moment” will dramatically affect energy prices and supply chains the world over.

It is significant that the Soil Association should be devoting half a day of its annual conference this week to consider the implications of a challenge that is so often overshadowed by the even bigger threat of climate change.

Enthusiastic consumption

Beyond that, the possibility that a global, interconnected nation such as the UK might be forced back predominantly on to its own productive resources to feed its people is gleefully dismissed as the narrow-minded, retro-protectionist rambling of those who can’t help feeling bad about their enthusiastic consumption of fairly-traded (and organic) bananas, coffee, tea, oranges, wine and sundry other delights grown in much warmer climates than our own - warmer for the time being, that is.

As if! Why feel bad about such a life-enriching flow of good things, especially if there’s a commensurate benefit for those involved in growing them for our delight. Eco-hedonists need to stand up and be counted lest the prospect of living in a carbon-constrained world sounds so grim that there’s a national uprising for Jeremy Clarkson to become prime minister.

But having just watched David Attenborough on Sunday evening taking us through a set of increasingly grisly scenarios for rising temperatures in the UK over the next few decades, some indication on the part of Defra that it is adopting a properly “precautionary” approach would be most welcome.

Two things are critical - the first of which is to ensure that the UK should always have enough agricultural land in good nick to maintain or even increase current levels of home-grown food production. By “in good nick” I mean not flooded and not stricken by drought (both of which could get a bit dodgy even in the near future, let alone in the longer term), not eroded away through poor agricultural practice to the point where yields start to decline (and there’s not much being done on that front), and not converted into roads or shopping malls.

Nor covered with hundreds of thousands of new houses as a consequence of the Treasury’s dogmatic drive to “predict and provide” as many houses as might be required in the growth areas of the south-east, regardless of the fact that other regions could accommodate such demand with a far lower loss of land.

The second priority is that we should have enough skilled farmers and growers to manage the land in smart, efficient and sustainable ways, whatever the complexities of farming in a carbon-constrained, rapidly warming environment. Defra is apparently unconcerned at the continued shrinkage in UK agriculture, with few qualms, for instance, about the very real possibility that so many more dairy farmers go out of business over the next couple of years that a “UK dairy industry” as such will cease to exist.

In his hard-hitting speech to the Oxford Farming Conference this month, Miliband referred again to the importance of securing “one planet farming” - rather than the kind of “three planet farming” we have now, given that for all 6bn human beings in the world to feed themselves in the way we do now in the UK, it would require an additional two planets. Good stuff. But the degree to which this radical “one planet” challenge is compatible with our increased dependence on a global food economy remains something of a mystery for all those interested in genuinely sustainable food and farming.

· Jonathon Porritt is founder director of Forum for the Future and chairman of the UK Sustainable Development Commission. forumforthefuture.org; sd-commission.org.uk. The Soil Association’s annual conference opens tomorrow in Cardiff. Details at soilassociation.org