How will we feed another 2 billion?
The world population is expected to grow from 7 billion in 2011 to 9.1 billion by 2050. In parallel, economic growth and individual wealth are shifting diets from predominantly starch-based to meat- and dairy-based, requiring more water. Producing 1 kg rice, for example, requires about 3500 litres of water, 1 kg of beef 15 000 litres of water and a cup of coffee about 140 litres.
This dietary shift has had the greatest impact on human water consumption over the past 30 years and is showing no sign of abating. The combination of rapid population growth and changing diets may increase the demand for food by 70% by 2050, according to the recently released 4th UN World Water Development Report.
The main challenge facing the agriculture sector will not be so much to grow 70% additional food in the next 40 years as to make 70% more food available on the plate. Reducing losses in storage and along the value chain would go some way towards offsetting the need for more production – and water.
Livestock not only provides food, of course, but also wool, hides and other products. It now contributes 40% of the global value of agricultural output. The expansion of land for livestock has created acute environmental concerns. It has led to deforestation in countries like Brazil, for instance, and, in countries belonging to the Organisation for Economic Co-operation and Development (OECD), intensive livestock production has become a major source of pollution. In 2008, 3 350 million ha were used as permanent meadows and for pasture, more than twice the area used for arable cropping and permanent crops.
Recent estimates suggest that nearly 2 billion hectares of land worldwide – an area twice the size of China – are seriously degraded, some irreversibly. Innovative technologies will be needed to improve crop yields and drought tolerance and deliver more efficient ways of using fertilizer and water. Among these figure water-harvesting technologies and drip irrigation, as well as technologies that recycle grey water in peri-urban agriculture. Grey water is produced by nonsanitary use of water in the home, such as in dishwashing or showering. FAO estimates that 70% of urban households in developing countries already participate in agriculture.
The development of biofertilization techniques would also increase water use efficiency by promoting higher nutrient absorption and crop growth rates. Timely agroclimatic information to help deal with increasing climate and rainfall variability, early warning systems and mechanization – which is still lagging behind in many countries – could also lead to an overall increase in water use efficiency.
Agriculture accounts for about 70% of all water withdrawals and as much as 90% in some fast-growing economies. Best estimates of future global agricultural water consumption – including both rainfed and irrigated agriculture – forecast an increase of about 19% by 2050. Much of the rise in water consumption for irrigation will affect regions already suffering from water scarcity.
- 4th edition of the World Water Development Report (WWDR4), 'Managing Water under Uncertainty and Risk', and
- A World of Science, Vol. 10, No. 2 'Water: Planning for an uncertain future'