Rampant population growth and rising wealth in developing countries  are driving up demand for food, a UK official says, while global warming also imperils food stores through decreased rainfall and crop failures.
The agriculture industry is going to have to double food production, but with less water than today. Another big threat to food supplies is biofuel production.
Food security and rising food prices are an "elephant in the room" that politicians must face up to quickly, said Professor John Beddington, UK's new chief scientific adviser.
In his first major speech as chief scientist, Beddington said the rush to grow biofuels  was compounding the problem, and cutting down rainforest to produce biofuel crops was "profoundly stupid."
Beddington, who took over the post from Sir David King nine weeks ago, was professor of applied population biology at Imperial College London. He is an expert on the sustainable use of renewable resources.
He told a conference in Westminster: "It is very hard to imagine how we can see a world growing enough crops to produce renewable energy and at the same time meet the enormous increase in the demand for food which is quite properly going to happen as we alleviate poverty."
Hilary Benn, the environment secretary,  said at the conference that the world's population was expected to grow from 6.2bn today to 9.5bn in less than 50 years' time. "How are we going to feed everybody?"
Beddington said “it is clear that science and research to increase the efficiency of agricultural production per unit of land is critical."
Sadly, nobody said anything about birth control.