Through the efforts and results of many organizations, activists and researchers we have begun to learn that these two topics are inextricably intertwined. For all the talk now of the water – energy nexus, there has been for thousands of years a more fundamental water – food nexus that we as humans have almost taken for granted time and again, to our detriment and occasional peril when the environmental circumstances change. To wit, the past couple of years of flooding and crop loss in Pakistan leading to a regional crisis that is still fermenting in the larger geopolitical context there, and the present famine and humanitarian emergencies in East Africa to which we have still paid inordinately little attention for the potential crisis that has been brewing for decades and will remain unresolved while first-world countries keep their eyes on their own internal issues.
So I seek to address to a large degree the issue of food, while maintaining the larger context of water that is the focus of this blog. It's an easier task than it might seem, with all of the tools linking our water usage and food needs that have arisen over the past several years. The Pacific Institute, led by Peter Gleick, has published six (soon to be seven) volumes of The World's Water, in each of which at least one section of their data collection has focused on agriculture and irrigation, which was featured most prominently in the 2000-2001 volume . Those of us who get our food at the grocery store remain several steps removed from the reality of those numbers, with our consumables prepackaged and, often, ready-to-eat. The water we might think about is in what to have to drink with that meal, and then who gets to wash the dishes afterward. We recognize the needs of irrigation when we fly over the central states of the U.S. or read the occasional news article about drought in various regions of the world. Most often we read about an abnormally low-rain summer in some portion of the U.S. or Europe, when groundwater resources are tapped to supplement surface water sources. The news from places with chronic shortages of surface water resources, with nearly perpetual famine, seems almost to fade to the background for many of us. Life is too often tough enough at home without worrying about how much the kids in Africa and South Asia have to eat or drink, yes?
The trouble is, we've come to distance ourselves from the water sources for growing our food to the point that we’ve taken both for granted in many parts of the world, and they’ve begun to run out. There is increasing academic and international attention to the complementary notions of water and food security, joining our long-running political and economic notions of energy security. We are witnessing subtle shifts in the manner and orientation of government support for agriculture, not least in the United States, where biofuel crops are subsidized as "alternative energy" and irrigation water costs the farmer little, if anything. Many researchers and academic observers, including my blogging and author friend David Zetland, call for the right-pricing of water resources in order to help a real water market grow, as the concept of water shifts in many places from commons resource to scarce commodity. If any econometric approach to such a personal issue can be considered heartfelt and genuine in its orientation and application, his End of Abundance certainly addresses the issue of emerging water scarcity in our global community, especially where competing interests in agriculture, urban growth, and industry have placed extraordinary pressures on the water and food resources. Not being an economist or statistician, I'm not afraid to admit that it is difficult reading at times, but Mr. Zetland's approach to the subject is reasoned and reassuring, and when I have finished the book I will certainly attempt to present a thoughtful and coherent review of his work on this blog. The economics of water and food, in such a transition to scarcity allocation as the growing global population spreads both renewable and nonrenewable resources across greater areas and higher demand, are such a tool for the treatment of emerging issues.
Subsidies and tariffs, so often our ad hoc and legacy approaches to economic control of national interests and international markets, do not necessarily apply as intended when it comes to the water – food nexus, and especially at subsistence levels of water supply and food production. In the subject of humanitarian aid, economics goes right out the window... but I’ll get to that another time. The 2008 Stockholm Water Prize, a sort of Nobel Prize in hydrology and water resources (since there still isn't a Nobel for Earth Science), was awarded to Prof. John Allan for his development of the virtual water concept:
"The water is said to be virtual because once the wheat is grown, the real water used to grow it is no longer actually contained in the wheat. The concept of virtual water helps us realize how much water is needed to produce different goods and services. In semi-arid and arid areas, knowing the virtual water value of a good or service can be useful towards determining how best to use the scarce water available."In citing this achievement, the Stockholm International Water Institute recognized that
"Virtual water has major impacts on global trade policy and research, especially in water-scarce regions, and has redefined discourse in water policy and management. By explaining how and why nations such as the U.S., Argentina and Brazil 'export' billions of liters of water each year, while others like Japan, Egypt and Italy 'import' billions, the virtual water concept has opened the door to more productive water use."The concept has led to the calculation, sometimes in great detail, of the "water footprint" of our food and the various organic and inorganic commodities in our lives. The results — how much we really depend upon water for necessities such as food and, especially in consumer societies, for our luxuries — are astounding and often frightening. Without this easy access to cheap water that many of us enjoy, what would life look like? We can make a fair guess at the answer to that question: America might look more like China, China more like India, India more like Ethiopia, and so much of the developing world more like Somalia...
In every one of these places, the primary use of water is for the production of food. The three largest countries by population (China at 1.35B, India at 1.3B, and the U.S. at 312M) are also those that have dedicated the largest arable areas to farming and food production [2, 3]: 137M hectares (ha; 1 sq km = 100 ha) in China, of which 37% is irrigated; 161M ha in India, of which 33% is irrigated; 176M ha in the United States, of which 13% is irrigated. In each case, seasonal rains comprise a major source of "green water" for farming and both surface water and groundwater are exploited, often to the point of overuse, as "blue water" sources for irrigation. We know well in the U.S. of highly productive areas that exist only by the allocation of blue water from distant sources, such as the Imperial Valley in southern California. Similar areas are supported by legacy practices in both China and India, much to the dismay of residents who often feel that the water could be better allocated to domestic uses, not to mention fellow farmers with lesser allocations by virtue of location or rights.
The mechanism of water allocation and rights varies considerably from one country to another, as do the levels of efficiency in irrigation practice and the economic value given to commodities for consumption and trade. The relative volume of food production for internal consumption and export also varies: much of U.S. grain production is exported while much of the meat remains in-country; China and India feed their own burgeoning populations with the grains and, increasingly, meat from their domestic production. However, the constant of necessity remains in every area of the world, and we are reminded time and again that nature makes a drought, but only humans can make a famine. Following on the present rising awareness of the water – food nexus, we may see a quiet revolution in the allocation of water to higher uses, whether that is food production for the pressing population growth of one country or trade for the economic development of another. These outcomes are not mutually exclusive, of course, and competing interests for resource allocation constitute the foundation of national economies and the international market system.
Food and water are, and will remain, the most important and fundamental of these interests as countries work toward security of both in an increasingly competitive and globalized economic system. The improved yields of new crop varieties and irrigated lands ensure that some of the best thinking is put into practice. My own Ph.D. advisor at the University of Wisconsin, Mutlu Ozdogan, currently participates in an integrative project led by USGS scientist Prashad Thenkabail and supported by the John Wesley Powell Center for Analysis and Synthesis:
"Global climate change is putting unprecedented pressure on global croplands and their water use, vital for ensuring future food security for the world's rapidly expanding human population. The end of the green revolution (increase in productivity per unit of land) era has meant declining global per capita agricultural production requiring immediate policy responses to safeguard food security amidst global climate change and economic turbulence. Global croplands are water guzzlers, consuming between 60-90% of all human water use. With urbanization, industrialization, and other demands (e.g., bio-fuels) on water there is increasing pressure to reduce agricultural water use by producing more food from existing or reduced areas of croplands (more crop per unit area) or increasing water use efficiency (more crop per unit of water). Our team will evaluate potential water savings that may emerge from: (i) replacing current crops with those that consume less water; (ii) increasing water use efficiency; (iii) altering human diets toward less water-consuming food; and (iv) emphasizing rainfed crop productivity to reduce stress on water-intensive irrigated croplands. We will create a "knowledge warehouse" to facilitate global food security in the twenty-first century by identifying and making available an advanced geospatial information system on croplands and their water use. Such a system will be global, consistent across nations and regions and provide information including: (a) crop types, (b) precise location of crops, (c) cropping intensities, (d) cropping calendar, (e) crop health/vigor, (f) watering methods (e.g., irrigated, supplemental irrigated, rainfed), (g) flood and drought information, (h) water use assessments, and (g) yield or productivity (expressed per unit of land and/or unit of water). Such a complex system requires coordination between multiple agencies leading to development of a seamless, scalable, and repeatable methodology."This is, of course, an international effort. Dr. Ozdogan is from Turkey and has worked extensively on the representation of agriculture in remote sensing and hydrologic models. Most recently, he published on the issue of the contribution of irrigation to agricultural productivity :
"...irrigation has the potential to increase carbon uptake by global cropland areas... especially in heavily irrigated semiarid areas such as northern India, the Indus River Valley, northeast China, the western United States, and the Nile River Valley. When accumulated across all irrigated areas and years, the total contribution of irrigation could exceed... a value equivalent to the total [productivity] of U.S. croplands..."It is certainly a significant result that, when properly applied, irrigation of croplands in various locations around the world could yet improve global agricultural productivity by an amount equivalent to adding another United States to the world food supply. Such advancement must come about responsibly, however:
"One outcome of this study is that irrigation has an important role in boosting primary productivity of croplands in water-limited areas. However, in the absence of good management practices, irrigation also has the potential to severely degrade the soil and water quality through waterlogging and soil salinization, and quantity through groundwater depletion. These forms of land and water degradation could have severe consequences for increasing crop yields with further concerns for income and employment in the long run. For example, large parts of formerly productive irrigated areas in India, China, and the United States are being abandoned due to deteriorating soil and water quality... So, while irrigation has the potential to substantially improve crop yields in arid and semiarid regions, these improvements may be eclipsed by degradation of resources that make cultivation possible in the first place. Therefore, irrigation along with good management practices is required to globally sustain and increase crop productivity in the coming decades."Food security for a growing global population is certainly one of the most prominent challenges facing our generation, but some of our best scientists are already at work on it.
 P. Gleick et al.: The World’s Water 2000-2001: The Biennial Report on Freshwater Resources. Volume 2 in a ongoing series by The Pacific Institute for Studies in Development, Environment, and Security. Published in cooperation with Island Press, ISBN 9781559637923.
 U.N. Food and Agriculture Organization (FAO): Statistical Yearbook. Available on-line at http://www.fao.org/economic/ess/ess-publications/ess-yearbook/en/.
 P. Gleick et al.: The World’s Water 2008-2009: The Biennial Report on Freshwater Resources. Volume 6 in a ongoing series by The Pacific Institute for Studies in Development, Environment, and Security. Published in cooperation with Island Press, ISBN 9781597265058.
 M. Ozdogan, 2011: Exploring the potential contribution of irrigation to global agricultural primary productivity. Global Biogeochemical Cycles, v. 25, paper no. GB3016, doi: 10.1029/2009GB003720.
M. Black and J. King, 2009: The Atlas of Water, Second Edition: Mapping the World’s Most Critical Resource. University of California Press, ISBN 9780520259348.