World food stocks are at an all-time low. If all food production stopped today, the planet would have just 40 days' worth of food. That was the sensational claim of Professor John Beddington, the government's chief scientist, in a speech about the food security crisis last week.

In the same week that Premier Foods chief executive Robert Schofield made a plea for farmers to grow more food, Beddington's comments have done nothing to quell the price of wheat, already 100% up on this time last year.

Claiming stocks would be under indefinite pressure due to an exploding global population - forecast to grow from six billion today to nine billion by 2050 - Beddington called food security "the elephant in the room" and claimed the "unprecedented" rise in commodity prices would continue, as climate change would cause harvest failure through floods or drought. On top of this, India and China's appetite for meat is growing and, as global wealth increased, it would lead to higher demand for grain-based animal feed.

Exacerbating the problem was the growth of biofuels, Beddington added, a point with which Schofield must sympathise.

UK farmers have been able to claim €1.45 per hectare subsidy for selling wheat into the fuel chain under Europe's biofuel policy for the past four years. Uptake has increased from 29,000 hectares in 2004 to 222,000 hectares in 2007.

"In the short term, growth in the biofuel market will continue as a result of regulation," Gareth Baker, corporate energy lawyer at Wragge & Co, predicts.

The UK's target is for 5% of fuel to come from renewable sources by 2010. As with most world trends, however, the US is leading the push. Since George W Bush spoke of the country's addiction to oil two years ago, targets have been set to replace more than 75% of oil imports from the Middle East by 2025. In the same period, wheat prices on futures markets have gone up from £72 to £193 per tonne.

By 2012, 7.5 billion gallons of biofuels will be produced in the US, nearly 9% of all motor fuel used. By 2017 this is expected to increase to 35 billion gallons.

Scottish Euro MP Struan Stevenson this week called Europe's target of 10% of fuel to be renewable by 2020 "insane" and linked the production of biofuels directly to global famine.

But the impact of biofuels is overstated, argues Alastair Dickie, director of crop marketing at the Home Grown Cereals Authority. Speaking at the HGCA's Processor Conference 2008 in London this week, he told delegates that shortages were being driven by historically low prices, adverse weather conditions and political interference, with low prices the most significant of these.

"If the price is right, the farmers will plant. In recent years prices got so low it made better sense to keep the fields fallow."

He adds: "The market is doing its thing. It will correct itself. As prices have risen, the farmers are responding."

He points out that planting is up 3% worldwide. This gives a harvest of 642 million tonnes, according to IGC estimates - in excess of the 2004 high of 628 million tonnes.

If Dickie sounds a note of caution, it is the weather. "IGC's estimates assume higher yields than in the past two years. But we all know what weather forecasters are like."

Owen Yeatman, a farmer and authority on biofuels, agrees. "If you can predict the weather you can predict the price of wheat. If there is a drought and the world supply runs even shorter, the sky is the limit."