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Water Pressure
MANY COUNTRIES already have insufficient fresh water. An increase in population will see many more experiencing water scarcity or water stress by 2050, while climate change will also undoubtedly have an impact on water supplies. A country’s average water supply obscures much regional variation. California’s burgeoning urban population is putting an increasing strain on the state’s limited resources, and in China the wheat-growing north is more water-stressed than its largely rice-growing south. Some countries, such as Egypt, are heavily dependent on water flowing in from another country, increasing their vulnerability. Irrigated crops are crucial to food security, and since 1950 the area under irrigation has doubled. Some methods are very wasteful of water, however, and badly drained irrigation can also lead to increased salinity. But support for farmers to enable them to develop small-scale, low-tech irrigation systems is vital to improving food security in poorer regions. Some countries are able to compensate for a scarcity of water by importing food. In China, much river water in the north is diverted from the fields to more profitable industrial uses, generating currency to pay for imported wheat to offset any shortfall. However, this makes China dependent on the global wheat market, and increases its food insecurity. Many less industrialized countries, especially those in Africa, are much more vulnerable to water stress: when they experience drought they are too poor to buy food elsewhere. Although the effects of climate change on water supplies are difficult to predict with precision, it is possible that the Middle East, Central Asia and southern Europe, already experiencing water stress, will see decreased river flows by the end of this century. Elsewhere, increased temperatures may initially increase glacial melt water flows from mountain ranges, but ultimately the flow may dry up, leading to devastating water shortages in areas such as northeast India, Bangladesh, and China – some of the most intensively farmed areas of the world.
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11 Animal Feed
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Nutritional Deficiencies
UNDER-NUTRITION is a major public health problem. It comes in many different forms, and can be caused by an inadequate amount of food, but also by a deficiency of certain nutrients in the diet. Different types of under-nutrition often occur in the same region, and they are almost always associated with poverty. The overall incidence of all kinds of under-nutrition is much higher in developing than in industrialized countries. The type of under-nutrition caused by a shortage of food is called protein-energy malnutrition, and is often associated with infectious diseases, such as measles and diarrhoea. This combination is a major cause of premature death, especially among children in South Asia and Africa. Other kinds of under-nutrition, such as iodine deficiency, are caused by a shortage of specific vitamins and minerals in the diet. Again, other factors often contribute to causing these deficiencies, such as infections and intestinal parasites that, for instance, reduce our ability to absorb nutrients from food. Vitamin A deficiency (VAD) is a major public health problem, affecting 140 million to 250 million pre-school children. It is a leading cause of blindness in developing countries and leaves sufferers at increased risk of infections. Iron deficiency anemia is the most common kind of micro-nutrient deficiency worldwide, and is also prevalent in industrialized countries. Some vitamin deficiency syndromes, including rickets (vitamin D deficiency), scurvy (vitamin C deficiency), pellagra (niacin deficiency) and beri-beri (thiamine deficiency), have been largely eradicated through extensive public health programmes, although they sometimes occur when people are dependent on a restricted supply of foods, such as may occur in refugee camps. International public health bodies continue in their efforts to eradicate the remaining micronutrient deficiencies by, for instance, mass supplementation of vitamin A and iodine. However, under-nutrition caused by shortage of food continues to be a huge problem.
Iodine Deficiency Disorders (IDD): • affect over 740 million people • are most prevalent in mountainous regions and river plains, where iodine has been leached from the soil by glaciers or floods • causes goitre (enlarged thyroid gland), mental retardation in children and reduced mental capacity in adults • are preventable by, for instance, fortifying salt with iodine
2 Feeding the World
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8 Contamination
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Over-Nutrition
PEOPLE IN INDUSTRIALIZED countries tend to lead sedentary lifestyles and eat more than they need. But the incidence of obesity is increasing worldwide. When countries industrialize, eating habits change and people tend to supplement their traditional diets, high in fruits, vegetables and cereals, with meat and dairy products. Obesity can lead to diabetes, and this is rapidly becoming a worldwide epidemic. Diabetes is most common in industrialized countries, but recent reports suggest that it is increasing most rapidly in Asia and the Caribbean. Both diabetes and obesity increase the risk of coronary heart disease (CHD). Until the 1980s CHD was common in industrialized countries, but improvements in medical treatment have led to falling rates in North America, Western Europe and Australia. In Japan, and in countries where people have maintained their traditional, plant-based diets, rates of CHD are low, while in Russia and Eastern Europe, rates are continuing to rise. In general, premature deaths from CHD are twice as common in men as in women, but in some regions this difference is narrowing. Indeed, diets worldwide are tending to converge, with the growth of fast-food outlets and global trade, and in many developing countries the incidence of heart disease is increasing as a consequence.
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31 Changing Diets
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