23 October 2011

Book Review: “Blue Revolution” by Cynthia Barnett

“Blue Revolution: Unmaking America’s Water Crisis”
By Cynthia Barnett
Published in 2011 by Beacon Press, Boston MA
ISBN 978-0-80700-317-6
Buy this book at Amazon.com (hardcover) or on your Kindle

Full disclosure: I solicited via e-mail and received a copy of this book for free in exchange for my promise of a published review.



I have racked my brain, and Google Maps, over the past weeks in a search for places in America that we humans have not altered the natural cycle and purity of our invaluable water resources. It makes me sad to find so few such places, so I often take heart that my chosen vocation as a hydrologist and water resource scientist is certainly secure, if not always appreciated for the level of education and dedication that this path demands. In that regard, Ms. Barnett’s new treatise on the emerging Blue Revolution is a welcome and appropriate summary of the challenges ahead of us, as both scientists and consumers amid the American landscape. We have much to remind us of how we got here; I have reviewed on this blog several books on the history of water use and misuse, allocation and subsidy, modification of whole river basins for our own purposes, and times when nature had its way with our species. To be sure, Ms. Barnett covers some of this material quite succinctly, but her focus remains on the present, on who is doing things right or, at least, is trying to do right by nature. An appropriate sample of imaginative solutions and cautionary tales are present, but the narrative approach is noticeably different here. It is not Ms. Barnett’s aim (as I perceive it) to dwell on the history in which we find so few salient, successful efforts and so many other works-in-progress, results TBD. She aims higher than a recapitulation of the usual stories from our past. As her subtitle suggests, it’s the past in which this crisis was made, and the same thinking won’t un-make the institutions and practices with which we’ve become accustomed over time.

Some outlets (e.g., The Economist and Scientific American) have addressed briefly the limited efforts at a “blue revolution” in aquaculture: coastal fisheries, like so many of our natural systems, are on the decline despite a perception of abundant renewability. In most cases, we have quite simply overestimated the natural elasticity of the resource and its systematic ability to recover from significant shocks. It’s not much different in freshwater resources, for that matter, and this is the fundamental focus of Ms. Barnett’s work. The concept of a “Blue Revolution” in freshwater grew from the global spread of the “Green Revolution” in agriculture, improving crop productivity around the world in various stages from the 1960s through the 1990s. Having reached almost every country by the end of the 20th century, that revolution comes back around more quietly now, with genetic crop modifications at the root of new improvements. Recognizing the pressures of exploding national and global populations, science seeks to feed the world in ways that traditional farming and agricultural practices likely cannot. The close connection between water and agriculture is also part of Ms. Barnett’s examination of present practice, in her discussion of consumptive water users and government subsidies, irrigation efficiencies and econometric approaches to supply reallocation and waste reduction. David Zetland, an author on water economics and fellow blogger that I have mentioned previously, appears in one of Ms. Barnett’s several interviews with current practitioners, and has much worthwhile to say on the ways forward. The economic approach to better water allocation is just part of the solution, however.

There are few books and fewer authors, especially in non-fiction, that still elicit a visceral reaction upon reading. If you read non-fiction on a regular basis, chances are that you also read from regular news outlets on paper or on the web, and it’s just possible that you are at times outraged at the seeming self-perpetuation of the status quo. You may even seek out a feel-good story of someone in power who is doing good for their constituents and right by the planet (or, failing that, give up on the news altogether for a time). This is exactly where Ms. Barnett’s background in investigative reporting and her deep interest in this particular subject matter come to shine. I consider myself an analyst, an observer on some of the topics covered on this blog, but an up-and-coming activist and potential leader when it comes to the water ethic that Ms. Barnett approaches here. Sometimes, and in the future, I (will) approach it as “National Water Policy” that is sorely missing from the federal agenda on natural resource stewardship in America. I’ve wanted to write on that myself, but it’s an exceptionally large issue around which to wrap a blog-length narrative. There is something more fundamental, however, that has stuck unexpressed in the back of my thoughts, and that Ms. Barnett’s work has helped to bring to the harsh light of reality: the problem is not a federal or even a state issue, though stronger environmental regulations certainly couldn’t hurt; it is, instead a movement to be grown from the roots in order to flower in a way that takes hold in our society and does not let go of our imaginations, our daily lives, and our work for the future. I follow the news on water issues from around the world with an almost religious fervor, so I think at times that I’ve seen quite a lot of discouraging and depressing stuff by now. There were moments, indeed whole chapters in Blue Revolution on the “Taproot of the Crisis” (regarding agricultural water-use practices) and the “Water – Industrial Complex” (regarding industrial and commercial practices), during which I expressed directly to Ms. Barnett that the tone of her narrative reached such depressing and discouraging depths, and that any positive outcome seemed in doubt. Such is the strength of her journalist’s near-surgical skill at reaching bare-handed in to the issues to pull them apart and expose the real guts of the problem, and then to suggest how we might address it at its root. Such also is the strength of her craft and encouragement that I kept reading, all the way to the positive and intensely thought-provoking payoff. But don’t get this book just to read the last couple chapters and think that you know what to do next; you would be deluding yourself, and cheating the world around you, if you did that…

In retrospect, those chapters (really, all these chapters) should be required reading in any high-school or college-level examination of American History, and especially in the environmental history of the United States. Ms. Barnett reaches into our history for the land ethic put forth by Aldo Leopold, a sound and stable (though seeming forgotten) basis on which our new water ethic might be founded. The esteemed Mr. Leopold, who established the very academic department at which I am now working on my Ph.D. at the University of Wisconsin, was a founding specialist on the natural ecology of a still-growing national frontier. He was, for that matter, an essential impetus for what I consider the third conservation movement in America and an author (A Sand County Almanac, among others) from whom we can draw continual and, indeed, practical inspiration. One of his sons, Luna Leopold, became a hydrologist and developed some of the fundamental standards of practice on which we still evaluate the form and health of streams, rivers and floodplains: his work with M.G. “Reds” Wolman and J.P. Miller on Fluvial Processes in Geomorphology (1964) remains a staple of the hydrologist’s graduate education. The history of what we might call the overriding American water ethic, up to this time, is skillfully outlined in Ms. Barnett’s early chapter spanning the time in the American West “From Reclamation to Restoration.” John Wesley Powell, with his own scientific specialties and his now-resurgent pronouncements on western water sustainability, expressed ethical and practical considerations that were roundly ignored in his own time. Nevertheless, it is refreshing to read a narrative on water in America that chooses not to address Las Vegas as either the death or savior of American water practice within the first chapter. Actually, Ms. Barnett saves that topic for the exact midpoint of Blue Revolution, amid visits abroad to flood specialists in The Netherlands, drought specialists in Australia’s own southwestern region, and water recycling specialists that have literally rebuilt Singapore from the ground up. Many of Ms. Barnett’s thoughts and accounts are embedded within an overarching narrative on two distinctly American problems illustrating the history of engineering folly that has made this crisis and brought us to the point of needing a new, fundamental ethic for its solution: the aquifers and the Everglades of Florida, as part of Ms. Barnett’s own backyard, and the Sacramento – San Joaquin – Central Valley project complex of central California. As strange and different as the Colorado River Basin has remained from the remainder of the U.S. in terms of water policy and practice, even greater an outlier seem the paths of past and present water management in California.

It is ultimately the final chapters of Ms. Barnett’s work that lift her narrative from depressing, rage-inducing disgust at the status quo to a hopeful, forward-looking plan for the future in the establishment of a national, possibly universal, water ethic. I suppose that an author’s skill at inducing such a reaction that the reader is moved to action should be considered a compliment, as I hope Ms. Barnett takes my opinions on the subject matter under her pen. Her treatment of that subject matter is skillful and concise, with no wasted effort, and she gets at the heart of the problems and our potential solutions with a keen interest. We have, as Blue Revolution outlines, a three-fold path of intense commitment before us at all levels of decision-making, from grass-roots activists to state and federal budget-makers: (1) better protection for and restoration of our natural resources, including the essential treatment and upkeep of our natural water systems as an integral component of civilization’s infrastructure; (2) necessary reforms in the system of water allocation and pricing, with greater emphasis given to high-value uses just as much as to conservation in essential agriculture and urban/domestic services; (3) a relentless program for education in the natural sciences, from grade school through adulthood, in and out of school, in order to instill in our fellow citizens, at the least, an understanding of the world around them and, if possible, a deep reverence for the sources of our health and wellness as citizens in an increasingly interwoven community. Part of that reverence arises from a sense of respect for the people and the nature around us, the invisible infrastructures that make our lives possible, and part of it comes from a sense of responsibility to make sure that the natural infrastructure remains viable and untainted, so that our children will have the advantages of a cleaner world as well. We must keep in mind not simply the bottom line on this financial quarter or fiscal year, but the legacy that our actions now will impress upon our future, and that of the generations to come.  The status quo, and the manner in which that came about, is an insufficient and inexcusable legacy given the ideas and resources presently available to us.

In 2003, another no less esteemed leader than Kofi Annan, as Secretary General to the United Nations, sent a message on World Water Day to delegates attending the plenary session of the third World Water Forum in Kyoto, Japan:
“It is often said that water crises and scarcities will at some point lead to armed conflict, but this need not be the case. Water problems have also been a catalyst for cooperation among peoples and nations... Scientists, local authorities, non-governmental organizations, private businesses and international organizations are pooling their efforts in the hopes of bringing about a much needed 'blue revolution' and to improve management of this vital resource. Whatever else divides the human community, whether we live upstream or downstream, in cities or in rural areas, water issues – the global water cycle itself – should link us in a common effort to protect and share it equitably, sustainably and peacefully.”
With Ms. Barnett’s book, a greater portion of that better way forward is illuminated. Following that path to respectful and sustainable treatment of our water resources won’t come without conflict and the angst of upheaval, but if we travel willingly and share the burdens equitably, such conflict will remain minimized and manageable. If just one person believes that a unifying water ethic is both possible and necessary, then there is hope that we can still turn away from the present course of decaying infrastructure, wasteful water practices and neglect of our natural heritage. If just one person expresses the desire to forge a better path, then that path immediately becomes a valid alternative to the destructive status quo. I know now that there are at least three of us...

19 October 2011

World Water Week Statement to the Rio+20 Summit

Editor's Note: the following text is quoted verbatim from a statement issued by the convening organizations at the Stockholm World Water Week conference and exposition that was last held during 21 - 27 August 2011.  That annual event is organized by the Stockholm International Water Institute (SIWI), which also hosts the UN Development Program (UNDP) Water Governance Facility (WGF) and the Swedish Water House (SWH).  The statement addresses the upcoming UN Conference on Sustainable Development (UNCSD) to be held in Rio de Janeiro in June 2012, also known as the "Rio+20 Summit" in celebration (and evaluation) of the landmark UN Conference on Environment and Development (UNCED) held in Rio in 1992. 

The preliminary agenda for the upcoming UNFCCC COP-17/CMP-7 meeting in Durban, South Africa, indicates no recognition of water and related issues to be addressed there.  Our best hope to get water on the global political agenda, other than the annual meetings at Stockholm WWW and the 6th triennial World Water Forum, to be held in March 2012, is likely through the UNCSD process.  

That is, short of convening a regular UN Conference on Water Sustainability to concatenate and analyze in real policy terms the outcomes from all the other initiatives and conferences... 



The Stockholm Statement to the 2012 United Nations Conference on Sustainable Development in Rio de Janeiro (Rio+20 Summit)

Water is the bloodstream of the green economy. Water, energy, and food are interlinked and interdependent; securing them is central to alleviating poverty and to creating a climate resilient and robust green economy. Population growth, expanding cities and accelerating economic activity increase the demand for energy and food and create unsustainable pressure on our water and land resources. By 2030, in a business as usual scenario, humanity’s demand for water could outstrip supply by as much as 40 per cent. This would place water, energy and food security at risk, increase public health costs, constrain economic development, lead to social and geopolitical tensions and cause lasting environmental damage.

The United Nations Conference on Sustainable Development in Rio de Janeiro in June 2012 (Rio+20 Summit) provides an opportunity for global leadership to harness economic activity at all levels to create new and sustainable development and eradicate poverty. The foundation for a resource efficient green economy must be built upon water, energy and food security – and these issues must be addressed in an integrated, holistic manner that values the natural environment and recognizes the carrying capacity of the planet. Action is critical at all levels to address inequities, especially for the ‘bottom billion’ who live in slums and impoverished rural areas and survive without access to safe drinking water, adequate sanitation, sufficient food and energy services. It is imperative to ensure that adequate water and sanitation services are available to the world’s population in accordance with the resolution of the UN General Assembly declaring these as a human right.

Accordingly, over and above achieving the Millennium Development Goals, we call for a universal provisioning of safe drinking water, adequate sanitation and modern energy services by the year 2030.

We call on local, municipal, and national governments and all major groups participating at the Rio+20 Summit to commit to achieving the following intervening targets by 2020:
  • 20% increase in total food supply-chain efficiency; reduce losses and waste from field to fork
  • 20% increase in water efficiency in agriculture; more nutrition and crop per drop 
  • 20% increase in water use efficiency in energy production; more kWh per drop
  • 20% increase in the quantity of water reused
  • 20% decrease in water pollution
In addition, we strongly urge that the following outcomes feature prominently within the Rio+20 Summit’s thematic focus areas:
  1. Green economy in the context of sustainable development and poverty eradication
    • All governments commit to sufficient investments in safe drinking water and sanitation services and hygiene education for its people
    • The current measurements of economic performance are expanded and complemented by indicators on environmental and social sustainability
    • Economic and social incentives are created to promote water use efficiency and protect freshwater ecosystems
  2. Creating an institutional framework for sustainable development
    •  Commit to policy and institutional reforms that create an enabling environment for the coherent and integrated management of water, energy and food
    • Enact national legislation that guarantees access to water and sanitation for all and protect freshwater ecosystems
    • Create cross-cutting frameworks that bridge ministries and sectors, leading the way to water, energy and food security in a green economy
The achievement of the aforementioned targets and outcomes would help the global leaders assembled at the Rio+20 Summit to deliver a new model of human and economic development and ensure a real impact on human well-being across the world.

18 October 2011

The U.S. Clean Water Act at 39...

The Federal Water Pollution Control Amendments of 1972, also known as the Clean Water Act, became law in the United States 39 years ago today.  Early in the day I opened my Twitter account to find some strangely aberrant claims about what the CWA does (e.g., "drinkable waterways"), and what we should "do for its birthday."  Well, anything that was later suggested would come too late and far-too-long-in-process to help the CWA see a happy 39th, but we can still work to build a better 40th year and a stronger set of rules on water quality for the future...

So, as much as I could in 140 characters at a time, I had a little Twitter rant to voice my concerns.  It's kind of difficult to keep up the steam of a long rant with that kind of limitation reducing concepts to sound-bites.  Nevertheless, I'm reproducing those tweets here for those of you who don't follow me on Twitter, or Facebook (where most of my tweets get mirrored) for that matter. 
  • The U.S. Clean Water Act was enacted 39 years ago today by Congressional override of President Nixon's veto. We are now in it's 40th year.
  • Nothing good will come of the bills before our present Congress, so let's wish for (and work on) good things for it's 40th b-day, shall we?
  • The U.S. Clean Water Act aims for fishable and swimmable waterways and drinkable tap water, but we need to be willing to pay for all that.
  • The U.S. Clean Water Act provides for waterway protection by EPA regs and Army Corps of Engineers permit rules, but enforcement costs $$.
  • The U.S. Clean Water Act regulates how much wetlands can get destroyed + how much As gets into your tap water. The rules could be better...
  • The U.S. Clean Water Act needs real rules for protection of headwater streams and riparian wetlands, not mere "guidance" for permitting.
  • The U.S. Clean Water Act needs regulators willing to enforce, w/o negotiation or prejudice, the letter of the law on chem/bio contaminants.
  • And finally, the U.S. Clean Water Act needs an executive agency (EPA) tied to Dept. of Justice and fully funded to police its jurisdiction.
That was all.  I think I said what I wanted and needed to say about the CWA, at least for that moment in time.  By all means, submit your comments, thoughts, support and/or (dis)agreement!

P.S. and by the way, my post for World Food Day on Sunday was a ResearchBlogging.org Editor's Selection for the week!  Woo hoo!  Many thanks to the editors there and you all, my dear readers!

16 October 2011

World Food Day / Blog Action Day

This post was chosen as an Editor's Selection for ResearchBlogging.orgToday is World Food Day, as designated by the United Nations on the anniversary of the founding of the Food and Agriculture Organization in 1945, and as such is this year's Blog Action Day on the topic of food. Last year around this time, I posted my commentary on the U.N. Resolution on the Human Right to Water and Sanitation on the occasion of the 2010 Blog Action Day on the topic of water.

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 [1]. 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 [4]:
"...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.

ResearchBlogging.orgReferences:

[1] 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.

[2] U.N. Food and Agriculture Organization (FAO): Statistical Yearbook. Available on-line at http://www.fao.org/economic/ess/ess-publications/ess-yearbook/en/.

[3] 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.

[4] 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.

Additional resources:

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.