Loaves, fishes and cereal yields

Tim Dyson argues that despite the explosion in world population, it will not outpace food production. Newspapers and television often give considerable coverage to those who argue that the world's food situation is deteriorating, and that we will soon face a global food shortage and increasing famines. This alarming viewpoint plays on a common belief that world population growth is outpacing food production.

This thesis stresses that since 1984 the human population has been growing faster than the output of the chief form of food, cereals, and that therefore global per capita cereal production has been declining. Indeed, it has been suggested that declines in cereal production per person have become established in all the world's main regions. The argument makes much of the fact that the average annual percentage growth rate of world cereal yields is falling.

As a research fellow I have been investigating these issues. It is obvious that the world food situation is unsatisfactory -- witness circumstances in places like Bangladesh or much of sub-Saharan Africa. Rapid demographic growth probably makes it harder to improve matters. And it is certain that population growth will provide the principal challenge to the world's food production capacity in the coming decades. There is certainly no room for complacency. But, in general, the facts do not support the most alarmist views.

Since 1984 the world's population has indeed been growing faster than cereal production. But the main explanation lies in the exceptionally low price of cereals on international markets, and the resulting, often deliberate, efforts to limit cereal production. In the early 1980s the European Community emerged as a major cereal exporting bloc. The ensuing competition between it and the North American cereal producers contributed greatly to the fall in international cereal prices and led to large areas of cropland being withdrawn from cereal cultivation, first in North America and later in Europe. Other cereal producers -- such as Argentina -- restricted their cereal cultivation because it was no longer profitable.

However, since the early 1980s, levels of per capita cereal production have increased significantly in South Asia and the Far East -- largely due to progress in India and China. Together these two regions contain more than half of humanity. Although the Middle East remains heavily dependent upon imported grains, it too has experienced rises in cereal output since the early 1980s. As a whole Latin America experienced a significant decline in cereal production per person. But if Argentina is excluded from the calculations then this regional decline becomes an increase. Only in sub-Saharan Africa do we find any real suggestion of populations growing so fast that cereal production has been unable to keep up -- and even there demographic growth is only part of the problem.

Because it is a much broader category, "food" production is more difficult to measure than the output of cereals. However, the Food and Agriculture Organisation of the United Nations produces an index of per capita food production. This suggests that world food output per person grew by about 5 per cent between 1979-81 and 1990-92, a rise very similar to that of the previous decade (1969-71 to 1980-82). Of the main world regions, only sub-Saharan Africa and North America have actually experienced declines in per capita food production since 1979-81 -- and in the latter region the explanation has little to do with rapid population growth.

In addition, there is considerable evidence that in most world regions diets are becoming increasingly varied. Thus in many Asian and Latin American countries there is now greater consumption of dairy products, vegetables and meat than was the case ten years ago. Furthermore, much of the land that was withdrawn from cereal cultivation during the 1980s was switched to other foodcrops. For example, in parts of northern China land previously used for rice is now being planted with potatoes. And in Bangladesh and India some coastal rice areas have been flooded to produce prawns for export. Other shifts in land use away from cereals have been towards non-edible crops -- witness the recent resurgence of linen clothes in European high streets.

Finally, let us return to the important issue of trends in world cereal yields, because given that the human population seems set to increase by more than 90 million people each year during the next two decades a slowdown in yield growth might be indicative of insurmountable problems looming ahead.

It is perfectly true -- as the pessimists claim -- that, in percentage terms, the average annual growth rate of world cereal yields is declining. However, it is highly misleading to describe these trends solely in percentage terms. Since the late 1950s, world cereal yields have increased almost exactly as a linear function of time -- rising by about 45 kilograms per hectare per year with remarkable regularity. It is on a linear basis that recent trends should probably be judged, and on this basis there is no evidence of a slowdown.

Global per capita cereal production has declined slightly. But this has happened mainly because of deliberate moves away from cereal cultivation in the world's richest regions, rather than because of population growth in the developing world. Measured on a linear scale, global cereal yield growth is not slackening. A continued yield increase of 45 kilograms per year will go a long way towards meeting the extra demand generated by demographic growth during the next few decades. In most world regions, food production per person has risen in the past decade. World population growth is not outpacing food production.

This is not to deny that rapid demographic growth can make matters more difficult. The plight of sub-Saharan Africa seems especially serious. Nor will it be easy to expand future food production to meet the needs of a growing world population; greater resources are required for international agricultural research and family planning. However, many of the more alarming statements about recent trends are mistaken and unhelpful.

Tim Dyson is professor of population studies at the London School of Economics and a research fellow in the Economic and Social Research Council's Global Environmental Change programme.