''I don't think we are going to run out (of food) if we get it right, but the point is, we don't have time to actually relax and say things are fine - in 20 years' time, the world population is going to be sky high, demand for food, demand for water, demand for energy, is going to be way up there,'' he said.
He said the world will need 40% more food, 30% more water and 50% more energy by the middle of the century at a time when climate change will be starting to have serious environmental impacts on the planet. Sir John said food price rises will hit the poorest hardest unless farming techniques intensify.
"There's no one simple solution. GM may be the answer for certain problems.