A UK government-commissioned study into food security has called for urgent action to avert global hunger.
"We know in the next 20 years the world population will increase to something like 8.3 billion people," he told BBC News.
"We know that urbanisation is going to be a driver and that something of the order of 65-70% of the world's population will be living in cities at that time.
"We know that the world is getting more prosperous and that the demand for basic commodities - food, water and energy - will be rising as that prosperity increases, increasing at the same time as the population."
He warned: "We have 20 years to arguably deliver something of the order of 40% more food; 30% more available fresh water and of the order of 50% more energy.
"We can't wait 20 years or 10 years indeed - this is really urgent."
How can a future global population of 9 billion people all be fed healthily and sustainably?
The Foresight project Global Food and Farming Futures explores the increasing pressures on the global food system between now and 2050. The Report highlights the decisions that policy makers need to take today, and in the years ahead, to ensure that a global population rising to nine billion or more can be fed sustainably and equitably.
The Foresight report makes a compelling case for urgent action to redesign the global food system to meet the challenge of feeding the world over the next 40 years.