Today, agriculture uses 11 % of the earth’s land surface about 1,527 million hectares or 3.78 billion acres for crop production. In addition, agriculture uses 70% of all the water withdrawn from aquifers, streams and lakes, but it is not really known what percentage of sustainable water use this represents. Mankind has been unable to fully quantify either groundwater use or renewable water availability. During the past half century the world’s agricultural production has grown between 2.5 and 3 times while the cultivated land area has grown only by 12%. This feat is often called the agricultural miracle or “Green Revolution” and was accomplished by doubling the areas of land that were irrigated. Fertilization, pesticides, hybrid crops and mechanized agriculture have also contributed to rapid increases in agricultural productivity and yield.
The U.N. forecasts that world population will continue to rise and grow from 7 billion people today to more than 9 billion in 2050. The Food and Agriculture Organization of the United Nations forecasts that in order to adequately feed 9 billion people, a 70 % increase in food production that will have to take place globally by 2050. There are reported to be 923 million people who are inadequately fed today and tremendous loss due to spoilage in the global food supply (30%). The rate of growth in agricultural food production has been slowing. In developing countries the growth rate is 1.5% half the growth rate of the past, still adequate to meet the projected food need if sustained, but the distribution of land and water resources does not match the forecasted need. According to the U.N. the available cultivated land per capita in low-income countries is less than half that of high-income countries, water resources are less abundant and the suitability that land for agriculture is generally lower.
Both irrigated and rain fed agriculture will have to respond to rising populations, but the key to food security is water and diet. According to the Food and Agriculture Organization of the United Nations doubling of current food production could be derived from already developed land and water resources, but might require a changing world diet especially in the developed world that would need to supply more food to the poorer nations by reducing the amount of animal protein in the developed nations’ diet. Using “conventional irrigated agriculture” it takes 420 gallons of water to produce one pound of rice; 1,800 gallons of water to produce one pound of beef; and 40 gallons of water to produce a cup of coffee. The dietary shift towards animal protein as nations become richer has increased world water consumption over the past 30 years.
Some land and water resources could be diverted to crop production, but in most cases this shift could have significant negative environmental and economic impacts. Increased water scarcity, loss of biodiversity and environmental services, desertification, expected reduction in water availability and some shift in seasonal flows is forecast to result from climate change in several places. Many rivers that serve as large contiguous irrigation systems in dry areas of the earth run dry from overuse before they reach the oceans. These, including the Colorado river, Murray-Darling (Australia), Krishna, Indo-Gangetic plains, Northern China, Central Asia, Northern Africa and Middle East are forecast to become more stressed. Groundwater-dependent irrigation systems in interior arid plains: India, China, central USA, Australia, North Africa, Middle East and others are using groundwater beyond their recharge rate. In some regions the groundwater aquifers were created a millennium ago when the earth’s climate was vastly different. In others the aquifer has simply been depleted by unsustainable use with the subsequent loss of buffer role that groundwater aquifers normally play seasonally or in drought years. The U.N. Food and Agricultural Organization already warns that agricultural water already is being allocated to other uses such as municipal supplies, environmental reserves and hydropower generation and removed from irrigation.
There are now proportionately fewer malnourished people in the world than there used to be (though the absolute number, 923 million, is extremely large). An emerging problem is food and diet quality. More calories do not mean better health. Over 87% of world’s population obtains enough calories and a growing portion of the world obtains too many calories, but many suffer nutrient deficiencies, especially in four nutrients: iron, zinc, iodine and vitamin A. In addition, there is growing evidence that over reliance on grains and processes food is having a negative impact on population health. Obesity is spreading from rich countries to less well-off places: Mexico has the second-largest share of obese people after the United States; Guatemala's obesity rate has quadrupled in 30 years yet, a large group of people in these countries suffer from nutritional deficiencies.
According to the National Institute of Health, research studies in the United States and Europe show that celiac disease is significantly more common now than it was a few generations ago. Scientists found that found that in the United States celiac disease is four times more common today than it was 50 years ago. According to Joseph Murray, M.D., professor of medicine at the Mayo Clinic in Rochester, MN, and a researcher into celiac disease the most likely factor is a change involving the quantity and quality of grain in our diets. “Consumption of wheat has increased steadily over the past 50 years, but it still is less than what it was a century ago, so the issue is not simple consumption,”; Dr. Murray noted. “It more likely involves the wheat itself, which has undergone extensive hybridization as a crop and undergoes dramatic changes during processing that involves oxidizers, new methods of yeasting, and other chemical processes. We have no idea what effect these changes may have on the immune system.” This is not a model of agriculture and diet that can hope to feed a robust species.