Alexander Muller, Food and Agriculture Organization of the United Nations (FAO) assistant director-general for natural resources, addressed these issues in Stockholm this week for World Water Week.
Over the last 50 years, the Earth's population has doubled and the global food system responded remarkably to the increase in food demand, Muller said. This was done through just a modest increase in total cropland – not more than 12 percent. The achievement occurred mainly through intensification of agricultural production, i.e. an increase in yield and cropping intensity, which in turn would not have been possible without irrigation.
Irrigated land has increased proportionally much faster than land under rainfed agriculture. Although the world's cultivated area has grown only by 12 percent over the last 50 years, irrigated area has doubled over the same period, accounting for most of the net increase in cultivated land. Meanwhile, agricultural production has grown between two-and-a-half and three times, thanks to significant increase in the yield of major crops.
Globally, some 300 million hectares of farmland is irrigated, accounting for 70 percent of all freshwater appropriations, Muller said. That is happening on only 20 percent of the world's cultivated land. At the same time, that irrigated land accounts for 40 percent of all agricultural production and 60 percent of cereal production.
Increasing regions of the world are facing water scarcity and face the risk of progressive breakdown of their productive capacity under a combination of demographic pressure and unsustainable agricultural practices.
Toward 2050, rising population and incomes are expected to require 70 percent more food production globally, and up to 100 percent more in developing countries. But some regions are coming very close to their potential to intensify food production, which is already leading to tension on access to natural resources, in particular water. East Asia and The Middle East are operating very close to their limits and will not be able to extend their agriculture much further, while substantial potential is still available in Latin America and in sub-Saharan Africa.
More needs to be done to reduce wastages between farm gates and the consumer. Estimates claim only about 50 percent of the food that is produced is actually consumed, the rest being lost in storage, distribution and at the level of end-users.
This amounts to food and water waste if production is irrigated, Muller said. Producing one calorie of food requires one liter of water. With the world's average daily caloric requirement at about 2,800 per person, the water needed to satisfy the daily food requirements of each individual on the planet is about 2,800 liters. To produce one hamburger takes 2,400 liters of water; a glass of milk takes 200 liters; one egg, 135 liters; and a slice of bread takes 40 liters.