An adequate diet is a basic human right but it will take innovation and political will to deliver it to all. Brian Heap argues that we need an agricultural revolution to secure food for the future.

The past half-century showed real progress in the quest to feed the world. Food production outpaced population growth in many regions, cereal production increased arithmetically from well under 300kg per person in the 1950s to more than 350kg in the 1980s. Since then, world grain output has fallen behind demographic growth not because of any sudden spurt in population growth or a genetic ceiling in plant breeding but primarily because of the effect of economic curbs on production by major producers in North America to maintain cereal prices. Demographic growth has overwhelmed cereal production in sub-Saharan Africa, however - the only region since the 1970s to be tortured by major famines.

Food production can be increased and malnutrition reduced through many avenues - appropriate technologies derived from existing and new knowledge, improvements in education and women's status relative to men's, local innovations by farmers, and national and international policies that promote trade, regulate food prices and exchange rates and improve access to markets.

To date, global trade in farm products has been liberalised only slowly, with tariffs on manufacturing goods falling from 40 per cent in 1950 to 4 per cent, while agricultural tariffs have remained above 40 per cent. These sombre facts remind us that ending hunger is a far more complex problem than dealing with just population or food, a trap into which well-intentioned single-interest groups are prone to fall.

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But exponential population growth continues. Techno-optimists note that science and technology have transformed the quality of life for many people and will continue to do so. But catastrophists warn of the danger of complacency because the dimensions of today's challenges are without precedent in the history of humankind.

Discussions about hunger polarise people into what Vaclav Smil of the University of Manitoba calls the cornucopians and catastrophists. Tim Dyson of the London School of Economics is quietly optimistic that farmers will be able to meet the volume of demand, provided there is no unforeseen calamity. Fertiliser use will increase, global cereal yields will reach about 4 tonnes per hectare, and information-intensive management procedures, including satellite remote-sensing and precision farming, will improve the efficiency of nitrogen application, soil quality and water usage.

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The big science question is how to invent a future in which food security is achievable for all and in an environmentally sustainable way.

Food security is defined as the secure ownership of, or access to, resources, assets and income-earning activities to offset risks, ease shocks and meet contingencies. In other words, not everyone is intended to be a subsistence farmer but everyone must possess the means to acquire an adequate diet. Today's farmers produce enough food to feed everyone in the world, yet 800 million remain food-insecure with food of insufficient quantity and quality for growth, activity and good health. If the world's supply of food had been evenly distributed in 1994, it would have provided an adequate diet of about 2,350 calories a day for 6.4 billion people - more than the actual world population. Physical redistribution of food in an equitable manner has so far proved impracticable and economically non-viable. It fails to supply the diversity of dietary needs and it does not generate enough income locally for small farmers - key factors for any attack on hunger.

Intensive systems of production and the green revolution have made major contributions to feeding the growing world population since the second world war. Certain practices, however, are unsustainable and result in land loss through soil degradation, desertification and urbanisation, crop yield increases that have started to decline in less developed countries, and the irreversible depletion of biodiversity. Globally, only about 0.26 hectares of cultivated land is available for each person to support food production. By 2050 it will be about 0.15 hectares. The rate of expansion of arable land has fallen below 0.2 per cent per year and continues to fall. About 40 per cent of the world's food requires irrigation and 70 per cent of the world's available water is used for agriculture. Raising food production to feed an extra 2 billion people will need to use the same amount of land with reduced reserves of available water.

Just as the world could not feed itself today with the farming methods of the 1940s, so farmers can hardly expect to meet the increased global demand in 30 or 40 years with their present methods. Without another agricultural revolution based on more sustainable methods the fate of the peoples of the less developed economies especially looks grim.

India and China have the triple problem of expanding populations, declining water reserves and diminishing arable land, though the depletion in soil fertility in China is more regional than was once thought.

Will biotechnology help? History tells us that we should not expect too much from a single source. The second wave of products in the biotechnology pipeline could produce crops - including vegetables and fruits - that are engineered to give higher yields, longer storage possibilities and better nutritive properties. They could have resistance to certain pests and diseases or give high-value products such as vaccines. They may even contribute towards more sustainable systems of production if transgenic plants can be employed that require fewer chemical applications, provide better drought tolerance and grow in unfavourable or even hostile environments.

In China alone, the area of transgenic crops has increased dramatically from less than 10,000 hectares in 1998 to 700,000 hectares in 2000. Yet the technology is too often perceived as the rich-man's toy.

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Norman Borlaug, father of the green revolution, has commented on the irony of farmers in the low-income, food-deficit nations being denied biotechnology when they have the greatest need of these products. He recommends that transnational companies share their expertise through partnerships with public research institutions, address agricultural problems not currently of high priority in the main transnational markets, and establish concessionary pricing structures in less developed countries so that poor farmers can benefit.

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Unless this happens, he believes hunger will remain largely a function of the failure of institutions, organisations and policies and not just the failure of markets and production.

Governments in poor countries have long discriminated against agriculture and been inclined to favour industry and cities rather than farmers and countryside. Less developed countries have been denied market access by more developed countries, aggravated by annual state payments to the agricultural sector by countries belonging to the Organisation for Economic Cooperation and Development that exceed Africa's entire gross domestic product.

If deepening poverty is to be reversed, the practical measures urgently needed include: applying the fruits of appropriate research and development; reforming land tenure; upgrading roads for marketing products; improving access to markets; and implementing good governance rather than corrupt practices and oppressive regimes.

The European Union has gained valuable experience in strengthening disadvantaged areas of Europe and the time is ripe, foreshadowed by the Johannesburg summit, for an even greater international effort in sub-Saharan Africa. Projects in India have already demonstrated how the communications and computer revolutions allow regions to leapfrog from outdated to modern technologies. Overcoming the prohibitive expense of protecting intellectual property is also a necessity. Bright young scientists returning home with new skills in plant biotechnology should be encouraged to find a central international fund through which they could protect their intellectual property in major potential markets. Such an initiative would send an important signal to the younger generation about the social, political and humanitarian intent to eliminate hunger in this century.

More than 1.3 billion people have incomes of a dollar a day or less. Some 2 billion are only marginally better off. We dare not allow this state to persist because ending hunger is not an abstract human responsibility, it is central to sustainable development. If sustainable development is to be taken seriously, it will become obligatory for more developed countries to modify their consumption patterns, for, as economist Amartya Sen has said, without change it will not be so much that humanity is trying to sustain the natural world, but that humanity is trying to sustain itself.

The emerging answer to the big science question is that we can end hunger but only if there is the political will to adopt appropriate policies and investment alongside the advances offered by research and development and appropriate technologies. Hunger will not end in regions where there is a continued lack of effective coordination of existing programmes of governmental and non-governmental agencies, let alone new initiatives. Failure to address such challenges plays into the hands of the catastrophists because it will perpetuate the denial of a basic human right for 800 million people - the right to an adequate diet.

Brian Heap is former vice-president and foreign secretary of the Royal Society, master of St Edmund's College, University of Cambridge, and special professor, University of Nottingham.

Mary Warnock, Janet Radcliffe-Richards and Martin Rees will be speaking at a panel discussion on the Big Questions in Science , chaired by Nancy Cartwright, at the BA Festival of Science at 2pm on 12 September 2002.

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The Big Science Questions is published by Jonathan Cape on October 3.

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