In 2008, the world suffered a food crisis as wheat, corn and rice prices rose dramatically. Food riots spread across Africa, with 14 countries experiencing major disturbances. But the strange thing was that there wasn't really a shortage of food. The 2007 harvest was slightly less (0.7%) than average, but not enough to warrant a food crisis.

"It wasn't a simple case of a production shortfall leading to a spike in food prices," Michael Puma from Columbia University, US, told environmentalresearchweb. "Rather it was a consequence of unforeseen interactions in the world's highly interconnected global food system."

The complex nature of the system meant that pressures on the wheat and corn market also impacted the rice market, causing panic hoarding and a dramatic spike in prices. Eventually the crisis was resolved when Japan released more than 300,000 tonnes of its surplus rice stock. "The interconnectivity of the global food system allowed the crisis to be resolved rapidly, but the origins of the crisis make it clear that this high interconnectivity is a double-edged sword," said Puma.

Using annual staple-food production and trade data from 1992 to 2009, Puma and his colleagues analysed the changing properties of the global food system. Their results show that the system has increased in complexity across time, with the number of global wheat and rice trade connections doubling, and trading of wheat and rice increasing by 42% and 90%, respectively.

"We see increasing trade activity across a broader range of countries for major cereals," said Puma. "In particular, Brazil, Argentina, Indonesia and China have substantially increased their agricultural trade activity over this time." The findings are published in Environmental Research Letters (ERL).

Next the scientists simulated the impact of continental-scale disruptions such as crop-pest outbreaks or weather extremes on the wheat and rice trade networks. They found that disruptions in European wheat and Asian rice production were considerably worse in a more interconnected network. They also show that some of the least developed countries, including Senegal, Haiti, Benin and Yemen, suffer the greatest import losses in a highly connected network, because of their increased dependence on imports of staple foods.

There are a number of ways to increase the resilience of the global food system. First, Puma and his colleagues suggest that more redundancy in the system needs to be encouraged – for example, ensuring that production of staple crops is distributed across multiple regions. They also suggest that broadening the genetic diversity of crops is important, to avoid entire harvests being wiped out by one kind of disaster. Meanwhile, reducing trade regulations would help to open up trade and avoid complete dependence on local markets. "At the same time, it is critical that countries throughout the world – both developed and developing – maintain some degree of self-sufficiency in staple food production, together with sizeable national food reserves," said Puma.

If we continue with globally interconnected business as usual then the study suggests we risk a severe food crisis at some point. Our dependence on readily available food supplies, as demonstrated by the panic buying and empty supermarket shelves in New York following Hurricane Sandy in October 2012, leaves us highly vulnerable when the connections do break down. If a major production shortfall did occur, then Puma and his colleagues think the outcome would be orders of magnitude worse than the 2008 food crisis, where there was no major decline in food production.

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