How can we feed the 2.5 billion more people – an extra China and India – likely to be alive in 2050? The UN says we will have to nearly double our food production and governments say we should adopt new technologies and avoid waste, but however you cut it, there are already one billion chronically hungry people, there's little more virgin land to open up, climate change will only make farming harder to grow food in most places, the oceans are overfished, and much of the world faces growing water shortages.
Fifty years ago, when the world's population was around half what it is now, the answer to looming famines was "the green revolution" – a massive increase in the use of hybrid seeds and chemical fertilisers. It worked, but at a great ecological price. We grow nearly twice as much food as we did just a generation ago, but we use three times as much water from rivers and underground supplies.
Food, farm and water technologists will have to find new ways to grow more crops in places that until now were hard or impossible to farm. It may need a total rethink over how we use land and water. So enter a new generation of radical farmers, novel foods and bright ideas.