http://news.bbc.co.uk/2/hi/americas/8213617.stm
Climate change, drought, population growth - they could all threaten future food supplies. But global agriculture, with its dependence on fuel and fertilisers is also highly vulnerable to an oil shortage, as Cuba found out 20 years ago.
Around Cuba's capital Havana, it is quite remarkable how often you see a neatly tended plot of land right in the heart of the city.
Sometimes smack bang between tower block estates or next door to the crumbling colonial houses, fresh fruit and vegetables are growing in abundance.
Some of the plots are small - just a few rows of lettuces and radishes being grown in an old parking space.
Other plots are much larger - the size of several football pitches. Usually they have a stall next to them to sell the produce at relatively low prices to local people.
Twenty years ago, Cuban agriculture looked very different. Between 1960 and 1989, a national policy of intensive specialised agriculture radically transformed Cuban farming into high-input mono-culture in which tobacco, sugar, and other cash crops were grown on large state farms.
Cuba exchanged its abundant produce for cheap, imported subsidised oil from the old Eastern Bloc. In fact, oil was so cheap, Cuba pursued a highly industrialised fuel-thirsty form of agriculture - not so different from the kind of farming we see in much of the West today.
But after the collapse of the Soviet Union, the oil supply rapidly dried up, and, almost overnight, Cuba faced a major food crisis. Already affected by a US trade embargo, Cuba by necessity had to go back to basics to survive - rediscovering low-input self-reliant farming...
