Researchers raise concern about fragility of the global grain supply

22 January 2009 by Tom Marshall

A major study of the vulnerability of Chinese cropland over the past 40 years has highlighted the growing fragility of the global grain supply.

Paddy field

In 2007, rice prices rocketed when global grain markets reacted to several events

The research, published in the journal Environmental Science & Policy, attributes drought and rapid urbanisation for this mounting exposure.

The UK team, led by Dr Elisabeth Simelton from the Sustainability Research Institute at the University of Leeds, used harvest and rainfall data to create an annual 'crop-drought vulnerability index'. An important part of this was an analysis of socio-economic factors that affect China's vulnerability to drought. As expected, the poorer landlocked regions were particularly sensitive to crop failure. What surprised the researchers was the exposure in wealthy coastal areas.

China produces 413 million tonnes of grain a year, or 18% of the world total. The country, which is home to 1·33 billion people, claims it is 95% self-sufficient for staple crops like rice, wheat and corn.

But rapid urbanisation, particularly in the south-east and by the coast, means less land is available to grow food, and space in some areas is saved for more profitable crops. The team report this is increasing China's vulnerability to harvest failure.

In 2007, rice prices rocketed when global grain markets reacted to several squeeze points: the market response to land grabs - the practice of countries buying land in other countries to grow crops; climate related crop failures in 2006 and 2007; nations stockpiling less grain than before and so running out quickly; and a move to grow more biofuels. The crisis led to some countries like Vietnam taking the extraordinary step of banning rice exports.

Though China has vowed not to replace grain with biofuel, there is a danger that increasing economic pressures, in the short term at least, may compel China to import more grain, leading to a repeat of events in 2007.

The food security challenge

Experts predict that if China's recent urbanisation trends continue, and crop failure forces the country to import just 5% more of its grain, this would swallow the entire amount exported by the rest of the world.

Grain mountain

China produces 18% of the world's grain each year

The knock-on effect on the food supply - and on prices - could be huge.

"China is a country undergoing a massive transformation, which is having a profound effect on land use," says lead author Simelton. "Growing grain is a low-profit exercise, and is increasingly being carried out on low-quality land with high vulnerability to drought."

Funded by two NERC programmes, the Quantifying & Understanding the Earth System programme and the Rural Economy and Land Use programme, the team looked at China's three main grain crops: rice, wheat and corn. They compared farming areas with a resilient crop yield with areas that have suffered large crop losses with only minor droughts.

"What surprised us was that it was not just the poor regions in the west and centre where crop failure could be an issue; even the rich coastal areas and south-east are just as susceptible."

"Quality land is increasingly being used for high profit crops, such as vegetables and flowers. Let's say we have an El Niño year causing drought in the north and flooding in the south. China would be out on the world market for grain," explained Simelton. "If the same thing happened in India and Brazil, this would have a very big impact on food availability."

As in 2007, poorer countries would be particularly affected.

Traditionally, China's farming has been small scale and inefficient. It plans to develop large-scale farming practices on a massive scale to become 95% self sufficient in the longer term. The country is also adapting to a changing climate. In the north-east where they used to grow wheat, temperature increases meant this crop was no longer viable. The area has recently switched to rice production.

"Our report considers this area to be more resilient now. This gives us faith that our analysis is sound," says Simelton.

"One aim is a better understanding of the socio-economic responses to difficult conditions so that we can improve models of climate change," she added.

India is experiencing similar urbanisation trends. Unlike China, where the population is predicted to level off by 2050, India's population is predicted to keep on rising beyond 2050.

The chapter on agriculture in the Intergovernmental Panel on Climate Change's Fourth Assessment Report (2007) states that if global average temperature rises more than 2°C worldwide yield declines are likely. But there is little research on how socio-economic factors may buffer the effect of climate change on crop productivity, according to the new paper.

The team plan to expand the analysis to sub-Saharan Africa.