Arguments about genetic modification, often wrongly characterised as science versus irrational nature-worshippers, have lost none of their passion. On one side are those who yearn for simple, high-tech solutions to complex problems. Against GM, there are ecological realities and scientific evidence. There is overwhelming evidence that farming took a wrong turn after the last war, with widespread use of artificial nitrogen fertilisers and sprays.

In Britain, we lost up to 95 per cent of our ancient woodlands, flower meadows, hedges and wildlife and saw massive losses of farms and farm workers' jobs. Farming became more oil-dependent. Our food lost vitamins, taste and diversity and our diet became unhealthy.

As the environmental and human cost of industrial farming became harder to deny, along came a new miracle cure - genetic engineering. Twenty years ago, GM promised unbelievable wonders - fruit that would never freeze, crops needing no fertiliser or sprays and food with vitamins and medicines engineered in. All food would soon be GM. Geneticists would engineer anything we wanted, taking a gene from a fish here, a pig there, adding a bacteria gene and maybe a bit of a virus.

The greatest coup by the GM companies, and their greatest scientific fraud, was to ensure no GM food had to be tested for safety. In America, they established the concept of "substantial equivalence" - which means that if a GM crop looks like its non-GM equivalent and grows like it, then it is it - no safety testing is needed before people eat it. GM maize could have added virus and antibiotic resistance genes, and a gene that makes it express an insecticide in every leaf, stem and root - but to the US government it looks and grows like maize, so it is safe to eat.

GM crops face mounting scientific evidence of uncertainty, risk and danger. But now, because of rising food prices, the GM industry's claim that GM is needed to feed the world is suddenly newsworthy again. However, a key reason for soaring food prices - higher oil costs leading to higher fertiliser prices - also presents a massive threat to GM crops. All current and planned GM crops depend on artificial, oil-based fertiliser to grow, and all need to be treated with pesticides to survive.

In 2006, the pro-GM US Department of Agriculture observed that "currently available GM crops do not increase yield potential" - a point already made by a 2004 UN Food and Agriculture Organisation report which acknowledged that "GM crops can have reduced yields". The recently published UN IAASTD report, the work of more than 400 international scientists, about the future of global food production under the challenges of climate change and population pressure, concluded that GM crops do not have much to offer.

Confirming an earlier FAO conference's conclusions, the IAASTD report acknowledged organic farming's real potential to help feed the world in an era of rising oil prices and the urgent need to cut greenhouse gases, because organic systems use solar energy and clover to fix nitrogen in
the soil, not oil and gas. The value of this approach was also confirmed in a report this year by the International Trade Centre, technical advisors to the WTO and UN. The new challenge we face is: how do we feed the world as oil and gas become costlier and scarcer, and as we cut greenhouse gases by 80 per cent by 2050? No one suggests the answer to that is GM.

Peter Melchett is the director of the Soil Association