As you leave Oxford station heading for London, there is an Oxfam advert that says: “Thanks to rising prices, some people can't afford fuel. Rice, bread, stuff like that.”

In the past 12 months there has been a sharp reversal of the 30-year trend of steadily declining global food prices. It has been called the “silent tsunami” and experts agree on three things. First, price increases were driven by a complex mix of factors including rising oil prices, the switch to biofuels, increased demand in China, poor harvests in Australia and commodity market speculation. Secondly, the steep and sudden increases are temporary, because farmers will increase output in response. Thirdly, in the long term the era of cheap food is over. Irrespective of short-term ups and downs, prices will rise in the future.

This last ineluctable conclusion is a consequence of supply and demand. The “green revolution” in agriculture has, since the 1960s, produced a staggering increase in output through plant-breeding, use of fertiliser and pesticides, and irrigation, albeit at huge environmental cost. But this revolution has reached a plateau, while the number of mouths to feed continues to grow, and people demand more food: not just the nearly one billion not getting enough to eat, but those in transition economies shifting from subsistence, plant-based diets to the more profligate food habits that we enjoy in the UK.

This is why the scientist Gordon Conway has argued that the world needs a “doubly green revolution” - in which agricultural output increases without further damage to the environment. Projections from climate-change models also suggest that it will become much harder to grow crops in some currently productive parts of the world.

Should our response to these challenges include genetically modified (GM) crops? Most agricultural scientists say yes. So far the European consumer has said no. For the scientist, GM is an extension of the past 10,000 years of genetic modification by agricultural selection. It is precision engineering as opposed to the blunderbuss of conventional breeding, and has the potential to transform agriculture in regions left out of the green revolution, such as sub-Saharan Africa, by creating crops that are more nutritious, resistant to disease or drought, and can grow without chemical fertilisers. In other words GM could help to produce more and better food with less environmental damage.

But as Robert Paarlberg so eloquently explains in his book Starved for Science, the tragedy is that Africa has, in large degree, been discouraged from adopting GM through the combined impact of European regulation, lobbying by NGOs and the media in Europe. During a severe drought in 2002 President Mwanawasa of Zambia rejected US food aid in the form of GM maize saying: “Simply because my people are hungry, that is no justification to give them food that is intrinsically dangerous to their health.” There is no evidence that the GM maize was dangerous. Any Times reader who has been to the US has probably eaten plenty of the same maize, but it is easy to see why Zambia was suspicious, given that Europeans are so pernickety about it.

Is it time for a change of heart in Europe? The first GM food sold in Britain, in the late 1990s, was Sainsbury's GM tomato paste, clearly labelled as such. It was cheaper and outsold the non-GM equivalent. Then various NGOs, combined with the media, turned against GM with the brilliant invention of the term “Frankenfoods”, and all supermarkets quickly declared a GM-free policy for fear of losing customers. Properly constructed opinion surveys show that the consuming public is by no means uniformly hostile to GM, but pressure groups have driven it out of the market in Europe, and the European Commission has supported this, introducing bizarre and unenforceable regulations on labelling.

Almost all first-generation GM foods (the tomato paste was an exception) benefited producers rather than consumers. Crops were engineered to resist pests or herbicide. The argument goes: “This is a new technology, perhaps there is a risk, so if there is no benefit to me why should I accept it” - and it has some force.

Wherever they are developed in the world, GM crops should be assessed for risk before they are used on a large scale. There are two possible risks - to the environment and to human health. The environmental safety of GM crops is, and should be, a concern, demanding a precautionary approach, with proper risk assessments before a crop is grown commercially.

All GM foods in Europe and North America are carefully assessed for health risks before they are allowed on the market - which is more than can be said for conventionally bred foods. Take, for instance, the familiar Braeburn apple that appeared, by chance and of uncertain parentage, about 50 years ago. No one knows how much genetic modification was involved and, as with all other new varieties of foods produced by conventional breeding, it has never been assessed for safety.

But we are now seeing a second generation of GM foods that could bring direct benefits to European consumers. For us, price and security are less critical than for sub-Saharan Africans, but GM tomatoes with enhanced anti-cancer properties or GM soya with fish oils that are good for your heart, might change people's view. Parents who have resolutely rejected GM food might think again if there were direct benefits for their children: no one objects to GM medicines such as human insulin produced by bacteria.

Once when I was explaining this point to Dan Glickman, then the US Agriculture Secretary, he said: “I see what you mean, John. We need the tomato with the Viagra gene.”

Returning to the Oxfam advert, what should we do for the poorest countries? One answer is to support agricultural research and development. Bilateral aid from the world's leading economies for agricultural development has been slashed in the past 20 years. If GM is to contribute to the doubly green revolution and empower local people, we should not leave it to the biotech industry alone. The necessary research should be done in these countries by their own scientists, for their own people, with our support.

Lord Krebs is Principal of Jesus College, Oxford, and a former chairman of the Food Standards Agency

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