Next Article in Journal
Impact of the City on the Rapid Increase in the Runoff and Transport of Suspended and Dissolved Solids During Rainfall—The Example of the Silnica River (Kielce, Poland)
Next Article in Special Issue
Burning Water, Overview of the Contribution of Arjen Hoekstra to the Water Energy Nexus
Previous Article in Journal
How Did the Late 1980s Climate Regime Shift Affect Temperature-Sensitive Fish Population Dynamics: Case Study of Vendace (Coregonus albula) in a Large North-Temperate Lake
Previous Article in Special Issue
Water Value Flows Upstream
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Water
Volume 12
Issue 10
10.3390/w12102696
water-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

The Water Footprint of Global Food Production

by
Mesfin M. Mekonnen
1,* and
Winnie Gerbens-Leenes
2
1
Department of Civil, Construction and Environmental Engineering, University of Alabama, Tuscaloosa, AL 35401, USA
2
Integrated Research on Energy, Environment and Society (IREES), University of Groningen, Nijenborg 6, 9747 AG Groningen, The Netherlands
*
Author to whom correspondence should be addressed.
Water 2020, 12(10), 2696; https://doi.org/10.3390/w12102696
Submission received: 26 July 2020 / Revised: 8 September 2020 / Accepted: 25 September 2020 / Published: 26 September 2020
(This article belongs to the Special Issue In Memory of Prof. Arjen Y. Hoekstra)
Browse Figures
Versions Notes

Abstract

:
Agricultural production is the main consumer of water. Future population growth, income growth, and dietary shifts are expected to increase demand for water. The paper presents a brief review of the water footprint of crop production and the sustainability of the blue water footprint. The estimated global consumptive (green plus blue) water footprint ranges from 5938 to 8508 km3/year. The water footprint is projected to increase by as much as 22% due to climate change and land use change by 2090. Approximately 57% of the global blue water footprint is shown to violate the environmental flow requirements. This calls for action to improve the sustainability of water and protect ecosystems that depend on it. Some of the measures include increasing water productivity, setting benchmarks, setting caps on the water footprint per river basin, shifting the diets to food items with low water requirements, and reducing food waste.

1. Introduction

Agriculture is by far the largest user of water. Agricultural production needs to increase by almost 50% by 2050 compared to 2012 to meet the rising demand for food, fiber, and biofuels. This is probably going to require more water. Most of the increase in agricultural production is expected to occur in Sub-Saharan Africa and South Asia, where the agricultural output will need to more than double by 2050 [1]. The expected increase in the rest of the world is around 30%. Agricultural production has increased by 260% between 1961 and 2018 [2]. During the same period, the harvested crop area increased by 47%, suggesting that 113% of the increase in production is linked to an increase in crop yield. The increase in crop yield between 1961 and 1990 was 72%, but between 1991 and 2018, the increase was 43%, indicating that yields are now rising at a slower rate than in previous decades [2]. The increase in crop yields was largely due to increased irrigation, improved crop varieties, agrochemical inputs, and improved soil and water management. However, the increase in crop productivity is not expected to continue indefinitely. In most parts of the world, yields for major crops have begun to stagnate [3,4]. Climate change, soil degradation, and salinization of irrigated areas will potentially limit future increases in production. Ray et al. [5] have shown that with the current rate of yield increase, it is not possible to meet the expected food demand by 2050. They have argued that some level of cropland expansion is needed to meet the food production deficits but at a higher environmental cost to biodiversity.
The amount of food available for human consumption is affected by the allocation of crops to other nonfood uses such as animal feed, bioenergy, and industrial uses. Globally, only 67% of the crop produced (by mass) or 55% of the calories produced is available for direct human consumption [6]. The remaining crop was allocated to animal feed (24% by mass) and other industrial use, including bioenergy (9% by weight). Animal production is less efficient than crop production in converting feed to human edible food [7,8,9,10]. As a result, only 12% of the 36% of the global calories used for animal feed will ultimately contribute to human diets [6].
In 2011, the global water footprint (WF) of agricultural production was 8362 km3/year (80% green, 11% blue, and 9% grey) [11]. World water demand is expected to increase by 20%–30% between 2010 and 2050 [12]. Demand for land and water resources has increased significantly, and these resources are expected to be scarcer in the future. Efficient water management in agriculture is needed to meet the growing demand for food and reduce poverty and hunger in a sustainable manner. The question is how the world will feed the global population without further impacting the freshwater and ecosystems. Several researchers have advocated for sustainable intensification [10,13,14,15,16], dietary changes, and reduction of food waste and loss [17,18,19] to feed the world. A number of studies have shown the value of virtual water trade in global water saving, reducing water scarcity, and it will help to reduce the risk of water scarcity [20,21,22,23]. This paper provides a brief review of the WF of food production, the water demand for different food products and diets, and the WF of food loss and waste. Finally, the paper presents the unsustainability of the current crop production showing the contribution of the main crops and countries toward the unsustainable blue WF.

2. The Water Footprint of Food

2.1. The Water Footprint of Different Food Products

Many global studies have assessed the water needed to produce crops at a high spatial resolution [24,25,26,27,28,29,30]. Estimates of the global consumptive (green plus blue) WF of crop production range from 5938 to 8508 km3/year (Table 1). The differences in the WF estimates are due to differences in the modeling approach, input data, including climate and cultivated area, the number of crops and their specification, and the models used. In terms of product coverage, Mekonnen and Hoekstra [29] explicitly estimated the WF of 146 individual crops, while the other authors included 20 or fewer individual crops and grouped the rest of the crops into two or four major groups. Although the estimated future global WF related to crop production under climate and land use change [31] was within the range of the estimates for the current period, Huang, Hejazi, Tang, Vernon, Liu, Chen, and Calvin [31], projected that the WF under climate and land use change will crease by as much as 22%. The increase in the WF is particularly large for the blue WF, which will increase by 70% by 2090, due to expansion in global irrigated area.
About 86% of the consumptive WF of crop production was related to the production of crops that can be used directly for human food consumption [29]. The other 14% was for fodder crops, fiber, rubber, and tobacco. Some of the food crops, such as maize, rapeseed, palm oil fruit, soybeans, and sunflower, are also used for biofuel production. This will lower the total WF that is used for human food consumption.
The total WF related to the production of crops that are used for human consumption across the world is shown in Figure 1. The WF is very large in the Indus River Basin, most parts of India, Eastern China, the northeast of the US, the Nile delta in Egypt, the western part of Indonesia, and many countries in Europe. The pie chart shows the major countries with a large share of the total global WF. India, China, and the US account for 38% of the total global green, blue, and grey WF.
The first estimate of the WF (cubic meter per tonne of crop) for 38 crops for a large number of countries was done by Hoekstra and Hung [33]. That study was further improved by Hoekstra and Chapagain by including a large number of primary and processed crop and animal products [32,34,35,36]. Mekonnen and Hoekstra [29] estimated the green, blue, and grey WF (cubic meter per tonne of product) for 354 primary and processed crop products. The WF of the primary crops was done at 5 arc-minute spatial resolution. In 2012, Mekonnen and Hoekstra [37] estimated the WF (cubic meter per tonne of product) for 106 animal products classifying the animal production into grazing, mixed, and industrial systems. Together, these databases are a rich source of data for other WF studies.
Figure 2 presents the WF of selected crop and animal products in terms of physical weight (L/kg) and nutritional energy content (L/kcal). The WF of food products differs significantly among crop and animal products. On average, the WF of animal food products is larger than the WF of crop food products with equivalent nutritional energy value. Especially, beef has a large WF, much larger than WFs of pork or chicken meat. However, animal feed of cows mainly consists of roughages from pasture land that are not human edible, while pigs and chickens consume crops from high-quality arable land that humans can also eat [37,38].
The first attempt to systematically quantify the WF of aquaculture was made by Pahlow et al. [39]. The study showed that the average WF of commercially fed fish was 1974 m3/tonne (83% green, 9% blue, and 8% grey). The study points out that aquafeed production could place considerable pressure on the water system in the form of water consumption and pollution. These pressures on the freshwater system from aquafeed production should be taken into account in order to develop aquaculture more sustainably.

2.2. The Water Footprint of Different Diets

In the next decades, the global demand for animal and processed food products is expected to increase [16,40]. These dietary shifts will influence the water, energy, land, and carbon footprints of people. The recent FAO and WHO report defines Sustainable Healthy Diets as “… dietary patterns that promote all dimensions of individuals’ health and wellbeing; have low environmental pressure and impact; are accessible, affordable, safe and equitable; and are culturally acceptable” [41]. The document further underlines the need for national food-based dietary guidelines to take the social, cultural, economic, ecological, and environmental circumstances of the country into consideration.
A large number of studies suggested that a healthy diet with reduced amounts of animal-based food products will have a corresponding benefit in terms of reducing environmental impacts and resource use [18,40,42,43,44,45,46,47,48,49]. Hoekstra was among the first that studied the effect of diet on the WF of consumption [42,43]. On average, the WF of animal food products is much larger than WFs of crop food products with equivalent nutritional energy value, as shown by Mekonnen and Hoekstra [37]. The average WF per calorie for beef was 20 times larger than for cereals and starchy roots. Per unit of protein, the WF of beef was 6 times larger than the WF of pulses. Therefore, replacing animal-based food products with the nutritionally equivalent plant-based products will reduce the WF of consumption. Hoekstra [43] showed that replacing meat-based diets by nutritionally equivalent plant-based diets would reduce the overall WF of consumption by 36% in industrial countries and by 15% in developing countries. Vanham, Mekonnen, and Hoekstra [47] showed that the WF of EU28 food consumption will reduce by 23% by shifting from current to healthy and by 38% to vegetarian diets. The WF reduction was mainly due to the reduction in the consumption of meat. In another similar study, Vanham, Hoekstra, and Bidoglio [48] showed that replacing the current diets with vegetarian diets would reduce the WF of consumption by 27% to 41% for different regions of EU28. In a more comprehensive global study covering 140 countries, Kim, Santo, Scatterday, Fry, Synk, Cebron, Mekonnen, Hoekstra, de Pee, Bloem, Neff, and Nachman [46] assessed the WF of 9 increasingly plant-based diets that aligned with the criteria for a healthy diet. The result showed that plant-based diets with modest amounts of low-food chain animals (i.e., forage fish, bivalve mollusks, insects) had relatively small WFs compared to exclusively plant-based (vegan) diets. However, the magnitude of changes in the WF varies widely from country to country due to variations in dietary changes, patterns of reference consumption, trends in food imports, and the water intensity of food products. The findings underscore the importance of trade, culture, and nutrition in the analysis of the WF of dietary patterns.
Healthy diets, however, do not always reduce the WF of consumption, especially if animal products are replaced by foods such as fruits and pulses with relatively large WFs [44,50,51,52]. Dietary recommendations should, therefore, aim to promote a healthy diet with minimal environmental impacts. In addition, these studies underscore the importance of dietary management and improving nutritional water productivity in order to decrease the pressure on water resources.

2.3. Water Lost with Food Loss and Waste

The world is paying more attention to the problem of food loss and waste, as reflected in Target 12.3 of the Sustainable Development Goals (SDGs), which calls for the per capita global food waste to be halved by 2030. FAO’s 2019 report on the State of Food and Agriculture was fully dedicated to the issue of food loss and waste, further underpinning the importance of addressing the issue [53,54]. Approximately one-third by weight and one-quarter by calories of food produced globally for human consumption was lost or wasted in 2009 [55,56].
Reducing food loss and waste will help to improve food security and alleviate the pressure on natural resources that have been used to produce it. Kummu, de Moel, Porkka, Siebert, Varis, and Ward [19] estimated that the WF of food loss and waste was 215 km3/year or 12%–15% of the global consumptive WF. Approximately three-quarters of the WF of food loss and waste is related to cereals and fruits and vegetables. Mekonnen and Fulton [50] found that reducing food loss and waste in the US food system was more effective than shifting from current to vegan or vegetarian diets to reduce the WF of consumption.

3. From Quantification to Sustainability Assessment

Over the last few years, the assessment of WFs of national consumption and production has shown significant improvement in terms of product coverage, spatial and temporal detail, and sustainability assessment [57]. Hoekstra and Hung [33] were the first to estimate the WF of national consumption of 38 crops for a large number of countries. The second global assessment made a number of improvements in terms of product coverage by including all crops and livestock products and other refinements [32,36]. The third global study made further refinements by assessing the national water footprints of production and consumption at a high spatial and temporal resolution [11,58]. In addition to the global studies on the WF of crop production mentioned earlier [24,25,26,27,28,29,59], other national [60,61,62,63,64], regional or basin [65,66], and global studies [28,67] have also traced and mapped the WF of consumption per country, but none of these studies assessed the sustainability of the blue WF of consumption at the place of production. The blue WF is unsustainable if it is above the available renewable blue water and violates the environmental flow requirements.
Van Oel et al. [68] carried out the first assessment of the sustainability of the WF in relation to Dutch consumption. In a case study for France, Ercin et al. [69] assessed the sustainability of the WF of consumption of France, identifying priority basins and products. Hoekstra and Mekonnen [70] assessed the sustainability and water-use efficiency of the UK’s WF of consumption. There are more recent works that have assessed the unsustainable blue WF of consumption for a single country or EU as a whole [71,72]. A few studies have assessed the sustainability of the WF of crop production and virtual water flows at a global level [73,74,75]. Other studies focused on sustainability of groundwater use [76,77,78,79,80].
In a more detailed global study, Mekonnen and Hoekstra [81] estimated that 513 km3/year, or 57% of the blue WF, related to crop production, was unsustainable. Approximately 75% of the global unsustainable blue WF is related to the production of only six crops (Figure 3a). These are wheat, rice, cotton, sugar cane, fodder, and maize. Five countries account for about 70% of the unsustainable blue WF (Figure 3b), India, China, the US, Pakistan, and Iran. Of the total unsustainable blue WF, 90% was for food and fodder crops, while only 10% was for fiber crops, rubber, and tobacco. Figure 4 shows the sustainable and unsustainable blue WF for global cereal production. The unsustainable portion of the blue WF is large in the Indus and Ganges river basins in India and Pakistan, in the north-eastern part of China, and in the US. High Plains aquifer. The study also showed that some 25% of global blue water can be saved by reducing the WF of each crop to the benchmark level.

4. Discussion

This paper provided a brief review of the WF of food production, the WF of different diets, and the volume of water lost due to food loss and waste. It also showed that global crop production leads to unsustainable use of blue water. Many regions of the world experience high water scarcity, depletion of groundwater, and deterioration of water quality [78,82,83]. In addition, the global WF associated with crop production is rapidly increasing, driven by growing demands for food and energy due to population growth, dietary changes, and increased per capita consumption. Changes in climate and land use will further put additional pressure on the available water resources [31].
We need to reduce the WF in many parts of the world to improve the sustainability of global water use. No single measure is a panacea for the global water problem. A combination of technological, behavioral, and policy instruments is needed. To this end, Hoekstra [84] has proposed three pillars under wise water allocation: (i) Setting upper limits on the WF per river basin; (ii) setting WF benchmarks per product; and (iii) fair WF shares per community. In a recent global study, Hogeboom et al. [85] estimated monthly blue WF caps that can be used by humans for all river basins in the world. In a case study for the Yellow River Basin, Zhuo et al. [86] assessed the role of reservoirs in the monthly blue WF caps in the basin. Mekonnen and Hoekstra [87] have made the first attempt to set a WF benchmark for all crops produced in the world. The study showed that the global consumptive WF can be reduced by as much as 39% by lowering the WF of all crops to the respective WF benchmarks. In a case study for wheat produced in China, Zhuo et al. [88] showed the value of setting the WF benchmark for the different climate conditions. Improving the water productivity of crop production through soil and water management, in combination with improved crop breeding, is one of the most effective measures to reduce the WF and keep it below the benchmark level [89,90,91]. Changing the pattern of consumption and reducing food losses and waste is another effective measure to reduce the pressure on water systems [17,18,19,47,49,50,92]. Virtual water trade from water abundant and highly productive regions to regions with limited water resources will help to reduce the risk of water scarcity and trespassing the environmental flow requirement. Economic valuation also needs to be integrated with the assessment of water footprints and virtual water flows in order to allocate water efficiently on a global scale [93,94].

5. Conclusions

Agricultural production is the main consumer of water, especially the production of animal foods, which have large WFs. Of the meat types, beef has the largest WF, WFs of pork and chicken meat are smaller. In general, vegetarian diets have smaller WFs. However, some foods of vegetal origin also have relatively large WFs, e.g., almonds or lentils. If more sustainable diets are promoted, it is important to take these WFs into account. For most foods, WFs are dominated by the green WFs, while blue and grey WFs are much smaller. However, the blue and grey WFs have a large environmental impact. Of the total global blue WF, 57% is unsustainable. This unsustainable footprint is dominated by only six crops, wheat, rice, cotton, sugar cane, fodder, and maize, and are located in only five countries, India, China, the US, Pakistan, and Iran. Population growth and dietary shifts, e.g., larger meat consumption, is expected to increase demand for water. The estimated global WF ranges from 5938 to 8508 km3/year, increasing by as much as 20% to 30% between 2010 and 2050. To improve sustainable water use, Hoekstra has proposed (i) to set an upper limit on the WF per river basin; (ii) set WF benchmarks per product; and (iii) define fair WF shares per community. In combination with virtual water trade and economic valuation, these measures will help to avoid unsustainable water use.

Author Contributions

Conceptualization, M.M.M.; investigation, M.M.M.; writing—original draft preparation, M.M.M.; writing—review and editing, W.G.-L.; visualization, M.M.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Acknowledgments

We dedicate this article to our esteemed friend Arjen Y. Hoekstra (1967–2019) who passed away suddenly in 2019.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. FAO. The Future of Food and Agriculture-Trends and Challenges; Food and Agriculture Organization: Rome, Italy, 2017. [Google Scholar]
  2. FAO. FAOSTAT Online Database; FAO: Rome, Italy, 2020. [Google Scholar]
  3. Grassini, P.; Eskridge, K.M.; Cassman, K.G. Distinguishing between yield advances and yield plateaus in historical crop production trends. Nat. Commun. 2013, 4. [Google Scholar] [CrossRef] [PubMed]
  4. Ray, D.K.; Ramankutty, N.; Mueller, N.D.; West, P.C.; Foley, J.A. Recent patterns of crop yield growth and stagnation. Nat. Commun. 2012, 3, 1293. Available online: http://www.nature.com/ncomms/journal/v3/n12/suppinfo/ncomms2296_S1.html (accessed on 13 April 2015). [CrossRef] [PubMed] [Green Version]
  5. Ray, D.K.; Mueller, N.D.; West, P.C.; Foley, J.A. Yield trends are insufficient to double global crop production by 2050. PLoS ONE 2013, 8, e66428. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  6. Cassidy, E.S.; West, P.C.; Gerber, J.S.; Foley, J.A. Redefining agricultural yields: From tonnes to people nourished per hectare. Environ. Res. Lett. 2013, 8, 034015. [Google Scholar] [CrossRef]
  7. Mekonnen, M.M.; Neale, C.M.U.; Ray, C.; Erickson, G.E.; Hoekstra, A.Y. Water productivity in meat and milk production in the USA from 1960 to 2016. Environ. Int. 2019, 132, 105084. [Google Scholar] [CrossRef]
  8. Wirsenius, S. Efficiencies and biomass appropriation of food commodities on global and regional levels. Agric. Syst. 2003, 77, 219–255. [Google Scholar] [CrossRef]
  9. Bouwman, A.F.; Van der Hoek, K.W.; Eickhout, B.; Soenario, I. Exploring changes in world ruminant production systems. Agric. Syst. 2005, 84, 121–153. [Google Scholar] [CrossRef]
  10. Tilman, D.; Balzer, C.; Hill, J.; Befort, B.L. Global food demand and the sustainable intensification of agriculture. Proc. Natl. Acad. Sci. USA 2011, 108, 20260–20264. [Google Scholar] [CrossRef] [Green Version]
  11. Hoekstra, A.Y.; Mekonnen, M.M. The water footprint of humanity. Proc. Natl. Acad. Sci. USA 2012, 109, 3232–3237. [Google Scholar] [CrossRef] [Green Version]
  12. Burek, P.; Satoh, Y.; Fischer, G.; Kahil, M.T.; Scherzer, A.; Tramberend, S.; Nava, L.F.; Wada, Y.; Eisner, S.; Flörke, M.; et al. Water Futures and Solution-Fast Track Initiative (Final Report); IIASA: Laxenburg, Austria, 2016. [Google Scholar]
  13. Cassman, K.G.; Grassini, P. A global perspective on sustainable intensification research. Nat. Sustain. 2020, 3, 262–268. [Google Scholar] [CrossRef] [Green Version]
  14. Drechsel, P.; Heffer, P.; Magen, H.; Mikkelsen, R.; Wichelns, D. Managing Water and Fertilizer for Sustainable Agricultural Intensification; International Fertilizer Industry Association (IFA): Paris, France; International Water Management Institute (IWMI): Colombo, Sri Lanka; International Plant Nutrition Institute (IPNI): Peachtree Corners, GA, USA; International Potash Institute (IPI): Horgen, Switzerland, 2015. [Google Scholar]
  15. Garnett, T.; Appleby, M.C.; Balmford, A.; Bateman, I.J.; Benton, T.G.; Bloomer, P.; Burlingame, B.; Dawkins, M.; Dolan, L.; Fraser, D.; et al. Sustainable intensification in agriculture: Premises and policies. Science 2013, 341, 33–34. [Google Scholar] [CrossRef] [PubMed]
  16. Godfray, H.C.J.; Beddington, J.R.; Crute, I.R.; Haddad, L.; Lawrence, D.; Muir, J.F.; Pretty, J.; Robinson, S.; Thomas, S.M.; Toulmin, C. Food security: The challenge of feeding 9 billion people. Science 2010, 327, 812–818. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  17. Foley, J.A.; Ramankutty, N.; Brauman, K.A.; Cassidy, E.S.; Gerber, J.S.; Johnston, M.; Mueller, N.D.; O’Connell, C.; Ray, D.K.; West, P.C.; et al. Solutions for a cultivated planet. Nature 2011, 478, 337–342. [Google Scholar] [CrossRef] [Green Version]
  18. Jalava, M.; Guillaume, J.H.A.; Kummu, M.; Porkka, M.; Siebert, S.; Varis, O. Diet change and food loss reduction: What is their combined impact on global water use and scarcity? Earth’s Future 2016, 4, 62–78. [Google Scholar] [CrossRef] [Green Version]
  19. Kummu, M.; de Moel, H.; Porkka, M.; Siebert, S.; Varis, O.; Ward, P.J. Lost food, wasted resources: Global food supply chain losses and their impacts on freshwater, cropland, and fertiliser use. Sci. Total Environ. 2012, 438, 477–489. [Google Scholar] [CrossRef] [PubMed]
  20. Liu, W.; Yang, H.; Liu, Y.; Kummu, M.; Hoekstra, A.Y.; Liu, J.; Schulin, R. Water resources conservation and nitrogen pollution reduction under global food trade and agricultural intensification. Sci. Total Environ. 2018, 633, 1591–1601. [Google Scholar] [CrossRef] [Green Version]
  21. Liu, W.; Antonelli, M.; Kummu, M.; Zhao, X.; Wu, P.; Liu, J.; Zhuo, L.; Yang, H. Savings and losses of global water resources in food-related virtual water trade. WIREs Water 2019, 6, e1320. [Google Scholar] [CrossRef] [Green Version]
  22. Mekonnen, M.M.; Hoekstra, A.Y. A global and high-resolution assessment of the green, blue and grey water footprint of wheat. Hydrol. Earth Syst. Sci. 2010, 14, 1259–1276. [Google Scholar] [CrossRef] [Green Version]
  23. Chapagain, A.K.; Hoekstra, A.Y.; Savenije, H.H.G. Water saving through international trade of agricultural products. HESS 2006, 10, 455–468. [Google Scholar] [CrossRef] [Green Version]
  24. Siebert, S.; Döll, P. Quantifying blue and green virtual water contents in global crop production as well as potential production losses without irrigation. J. Hydrol. 2010, 384, 198–217. [Google Scholar] [CrossRef]
  25. Liu, J.; Yang, H. Spatially explicit assessment of global consumptive water uses in cropland: Green and blue water. J. Hydrol. 2010, 384, 187–197. [Google Scholar] [CrossRef]
  26. Liu, J.; Zehnder, A.J.B.; Yang, H. Global consumptive water use for crop production: The importance of green water and virtual water. Water Resour. Res. 2009, 45. [Google Scholar] [CrossRef] [Green Version]
  27. Hanasaki, N.; Inuzuka, T.; Kanae, S.; Oki, T. An estimation of global virtual water flow and sources of water withdrawal for major crops and livestock products using a global hydrological model. J. Hydrol. 2010, 384, 232–244. [Google Scholar] [CrossRef]
  28. Fader, M.; Gerten, D.; Thammer, M.; Heinke, J.; Lotze-Campen, H.; Lucht, W.; Cramer, W. Internal and external green-blue agricultural water footprints of nations, and related water and land savings through trade. Hydrol. Earth Syst. Sci. 2011, 15, 1641–1660. [Google Scholar] [CrossRef] [Green Version]
  29. Mekonnen, M.M.; Hoekstra, A.Y. The green, blue and grey water footprint of crops and derived crop products. HESS 2011, 15, 1577–1600. [Google Scholar] [CrossRef] [Green Version]
  30. Rost, S.; Gerten, D.; Bondeau, A.; Lucht, W.; Rohwer, J.; Schaphoff, S. Agricultural green and blue water consumption and its influence on the global water system. Water Resour. Res. 2008, 44. [Google Scholar] [CrossRef] [Green Version]
  31. Huang, Z.; Hejazi, M.; Tang, Q.; Vernon, C.R.; Liu, Y.; Chen, M.; Calvin, K. Global agricultural green and blue water consumption under future climate and land use changes. J. Hydrol. 2019, 574, 242–256. [Google Scholar] [CrossRef]
  32. Hoekstra, A.Y.; Chapagain, A.K. Globalization of Water: Sharing the Planet’s Freshwater Resources; Blackwell: Oxford, UK, 2008. [Google Scholar]
  33. Hoekstra, A.Y.; Hung, P.Q. Virtual Water Trade: A Quantification of Virtual Water Flows between Nations in Relation to International Crop Trade, 11th ed.; IHE: Delft, The Netherlands, 2002. [Google Scholar]
  34. Chapagain, A.K.; Hoekstra, A.Y. Water Footprints of Nations, 16th ed.; UNESCO-IHE: Delft, The Netherlands, 2004. [Google Scholar]
  35. Chapagain, A.K.; Hoekstra, A.Y. Virtual Water Flows between Nations in Relation to Trade in Livestock and Livestock Products; Value of Water Research Report Series No. 13; UNESCO-IHE: Delft, The Netherlands, 2003. [Google Scholar]
  36. Hoekstra, A.Y.; Chapagain, A.K. Water footprints of nations: Water use by people as a function of their consumption pattern. Water Resour. Manage. 2007, 21, 35–48. [Google Scholar] [CrossRef]
  37. Mekonnen, M.; Hoekstra, A. A global assessment of the water footprint of farm animal products. Ecosystems 2012, 15, 401–415. [Google Scholar] [CrossRef] [Green Version]
  38. Gerbens-Leenes, P.W.; Mekonnen, M.M.; Hoekstra, A.Y. The water footprint of poultry, pork and beef: A comparative study in different countries and production systems. Water Resour. Ind. 2013, 1–2, 25–36. [Google Scholar] [CrossRef] [Green Version]
  39. Pahlow, M.; van Oel, P.R.; Mekonnen, M.M.; Hoekstra, A.Y. Increasing pressure on freshwater resources due to terrestrial feed ingredients for aquaculture production. Sci. Total Environ. 2015, 536, 847–857. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  40. Tilman, D.; Clark, M. Global diets link environmental sustainability and human health. Nature 2014, 515, 518–522. [Google Scholar] [CrossRef] [PubMed]
  41. FAO; WHO. Sustainable Healthy Diets-Guiding Principles; Food and Agriculture Organization (FAO); World Health Organization (WHO): Rome, Italy, 2019. [Google Scholar]
  42. Hoekstra, A.Y. The hidden water resource use behind meat and dairy. Anim. Front. 2012, 2, 3–8. [Google Scholar] [CrossRef]
  43. Hoekstra, A.Y. The water footprint of animal products. In The Meat Crisis: Developing More Sustainable Production and Consumption; D’Silva, J., Webster, J., Eds.; Earthscan: London, UK, 2010; pp. 22–33. [Google Scholar]
  44. Springmann, M.; Clark, M.; Mason-D’Croz, D.; Wiebe, K.; Bodirsky, B.L.; Lassaletta, L.; de Vries, W.; Vermeulen, S.J.; Herrero, M.; Carlson, K.M.; et al. Options for keeping the food system within environmental limits. Nature 2018, 562, 519–525. [Google Scholar] [CrossRef] [PubMed]
  45. Willett, W.; Rockström, J.; Loken, B.; Springmann, M.; Lang, T.; Vermeulen, S.; Garnett, T.; Tilman, D.; DeClerck, F.; Wood, A.; et al. Food in the anthropocene: The EAT-lancet commission on healthy diets from sustainable food systems. Lancet 2019, 393, 447–492. [Google Scholar] [CrossRef]
  46. Kim, B.F.; Santo, R.E.; Scatterday, A.P.; Fry, J.P.; Synk, C.M.; Cebron, S.R.; Mekonnen, M.M.; Hoekstra, A.Y.; de Pee, S.; Bloem, M.W.; et al. Country-specific dietary shifts to mitigate climate and water crises. Glob. Environ. Chang. 2020, 62, 101926. [Google Scholar] [CrossRef]
  47. Vanham, D.; Mekonnen, M.M.; Hoekstra, A.Y. The water footprint of the EU for different diets. Ecol. Indic. 2013, 32, 1–8. [Google Scholar] [CrossRef]
  48. Vanham, D.; Hoekstra, A.Y.; Bidoglio, G. Potential water saving through changes in European diets. Environ. Int. 2013, 61, 45–56. [Google Scholar] [CrossRef]
  49. Jalava, M.; Kummu, M.; Porkka, M.; Siebert, S.; Varis, O. Diet change-a solution to reduce water use? Environ. Res. Lett. 2014, 9, 074016. [Google Scholar] [CrossRef]
  50. Mekonnen, M.M.; Fulton, J. The effect of diet changes and food loss reduction in reducing the water footprint of an average American. Water Int. 2018, 43, 860–870. [Google Scholar] [CrossRef]
  51. Tom, M.S.; Fischbeck, P.S.; Hendrickson, C.T. Energy use, blue water footprint, and greenhouse gas emissions for current food consumption patterns and dietary recommendations in the USA. Environ. Syst. Decis. 2016, 36, 92–103. [Google Scholar] [CrossRef]
  52. Harris, F.; Moss, C.; Joy, E.J.M.; Quinn, R.; Scheelbeek, P.F.D.; Dangour, A.D.; Green, R. The water footprint of diets: A global systematic review and meta-analysis. Adv. Nutr. 2019, 11, 375–386. [Google Scholar] [CrossRef] [PubMed]
  53. FAO. The State of Food and Agriculture 2019. Moving Forward on Food Loss and Waste Reduction; Food and Agriculture Organization (FAO): Rome, Italy, 2019. [Google Scholar]
  54. Liu, J.; Lundqvist, J.; Weinberg, J.; Gustafsson, J. Food losses and waste in china and their implication for water and land. Environ. Sci. Technol. 2013, 47, 10137–10144. [Google Scholar] [CrossRef] [PubMed]
  55. Searchinger, T.; Waite, R.; Hanson, C.; Ranganathan, J. Creating a Sustainable Food Future’ Shows that It is Possible-But There is no Silver Bullet; World Resources Institute: Washington, DC, USA, 2019. [Google Scholar]
  56. FAO. Global Food Losses and Food Waste-Extent, Causes and Prevention; Food and Agriculture Organization (FAO): Rome, Italy, 2011. [Google Scholar]
  57. Hoekstra, A.Y. Water footprint assessment: Evolvement of a new research field. Water Resour. Manage. 2017, 31, 3061–3081. [Google Scholar] [CrossRef] [Green Version]
  58. Mekonnen, M.M.; Hoekstra, A.Y. National Water Footprint Accounts: The Green, Blue and Grey Water Footprint of Production and Consumption; UNESCO-IHE: Delft, The Netherlands, 2011. [Google Scholar]
  59. Rost, S.; Gerten, D.; Heyder, U. Human alterations of the terrestrial water cycle through land management. Adv. Geosci. 2008, 18, 43–50. [Google Scholar] [CrossRef] [Green Version]
  60. Mekonnen, M.M.; Hoekstra, A.Y. Water conservation through trade: The case of Kenya. Water Int. 2014, 39, 1–18. [Google Scholar] [CrossRef] [Green Version]
  61. Zhuo, L.; Mekonnen, M.M.; Hoekstra, A.Y. Consumptive water footprint and virtual water trade scenarios for China — With a focus on crop production, consumption and trade. Environ. Int. 2016, 94, 211–223. [Google Scholar] [CrossRef]
  62. Bulsink, F.; Hoekstra, A.Y.; Booij, M.J. The water footprint of Indonesian provinces related to the consumption of crop products. HESS 2010, 14, 119–128. [Google Scholar] [CrossRef] [Green Version]
  63. Marston, L.; Ao, Y.; Konar, M.; Mekonnen, M.M.; Hoekstra, A.Y. High-resolution water footprints of production of the united states. Water Resour. Res. 2018, 54, 2288–2316. [Google Scholar] [CrossRef]
  64. Schyns, J.; Hamaideh, A.; Hoekstra, A.; Mekonnen, M.; Schyns, M. Mitigating the risk of extreme water scarcity and dependency: The case of jordan. Water 2015, 7, 5705–5730. [Google Scholar] [CrossRef] [Green Version]
  65. Mekonnen, M.; Pahlow, M.; Aldaya, M.; Zarate, E.; Hoekstra, A. Sustainability, efficiency and equitability of water consumption and pollution in latin America and the caribbean. Sustainability 2015, 7, 2086–2112. [Google Scholar] [CrossRef] [Green Version]
  66. Zeitoun, M.; Allan, J.A.; Mohieldeen, Y. Virtual water ‘flows’ of the nile basin, 1998–2004: A first approximation and implications for water security. Glob. Environ. Change 2010, 20, 229–242. [Google Scholar] [CrossRef]
  67. Chen, Z.-M.; Chen, G.Q. Virtual water accounting for the globalized world economy: National water footprint and international virtual water trade. Ecol. Indicators 2013, 28, 142–149. [Google Scholar] [CrossRef]
  68. Van Oel, P.R.; Mekonnen, M.M.; Hoekstra, A.Y. The external water footprint of The Netherlands: Geographically-explicit quantification and impact assessment. Ecolog. Econ. 2009, 69, 82–92. [Google Scholar] [CrossRef]
  69. Ercin, A.E.; Mekonnen, M.M.; Hoekstra, A.Y. Sustainability of national consumption from a water resources perspective: The case study for France. Ecolog. Econ. 2013, 88, 133–147. [Google Scholar] [CrossRef]
  70. Hoekstra, A.Y.; Mekonnen, M.M. Imported water risk: The case of the UK. Environ. Res. Lett. 2016, 11, 055002. [Google Scholar] [CrossRef]
  71. Dolganova, I.; Mikosch, N.; Berger, M.; Núñez, M.; Müller-Frank, A.; Finkbeiner, M. The water footprint of European agricultural imports: Hotspots in the context of water scarcity. Resources 2019, 8, 141. [Google Scholar] [CrossRef] [Green Version]
  72. Finogenova, N.; Dolganova, I.; Berger, M.; Núñez, M.; Blizniukova, D.; Müller-Frank, A.; Finkbeiner, M. Water footprint of German agricultural imports: Local impacts due to global trade flows in a fifteen-year perspective. Sci. Total Environ. 2019, 662, 521–529. [Google Scholar] [CrossRef]
  73. Wang, R.; Zimmerman, J. Hybrid analysis of blue water consumption and water scarcity implications at the global, national, and basin levels in an increasingly globalized world. Environ. Sci. Technol. 2016, 50, 5143–5153. [Google Scholar] [CrossRef]
  74. Jägermeyr, J.; Pastor, A.; Biemans, H.; Gerten, D. Reconciling irrigated food production with environmental flows for sustainable development goals implementation. Nat. Commun. 2017, 8, 15900. [Google Scholar] [CrossRef] [Green Version]
  75. Rosa, L.; Chiarelli, D.D.; Tu, C.; Rulli, M.C.; D’Odorico, P. Global unsustainable virtual water flows in agricultural trade. Environ. Res. Lett. 2019, 14, 114001. [Google Scholar] [CrossRef]
  76. Dalin, C.; Taniguchi, M.; Green, T.R. Unsustainable groundwater use for global food production and related international trade. Glob. Sustain. 2019, 2, e12. [Google Scholar] [CrossRef] [Green Version]
  77. Dalin, C.; Wada, Y.; Kastner, T.; Puma, M.J. Groundwater depletion embedded in international food trade. Nature 2017, 543, 700. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  78. Wada, Y.; van Beek, L.P.H.; Bierkens, M.F.P. Nonsustainable groundwater sustaining irrigation: A global assessment. Water Resour. Res. 2012, 48, W00L06. [Google Scholar] [CrossRef]
  79. Scanlon, B.R.; Faunt, C.C.; Longuevergne, L.; Reedy, R.C.; Alley, W.M.; McGuire, V.L.; McMahon, P.B. Groundwater depletion and sustainability of irrigation in the USA high plains and central valley. Proc. Natl. Acad. Sci. USA 2012, 109, 9320–9325. [Google Scholar] [CrossRef] [Green Version]
  80. Marston, L.; Konar, M.; Cai, X.; Troy, T.J. Virtual groundwater transfers from overexploited aquifers in the United States. Proc. Natl. Acad. Sci. USA 2015, 112, 8561–8566. [Google Scholar] [CrossRef] [Green Version]
  81. Mekonnen, M.M.; Hoekstra, A.Y. Sustainability of the blue water footprint of crops. Arizona department Water Resour. 2020, 143, 103679. [Google Scholar] [CrossRef]
  82. Mekonnen, M.M.; Hoekstra, A.Y. Four billion people facing severe water scarcity. Sci. Adv. 2016, 2. [Google Scholar] [CrossRef] [Green Version]
  83. Vörösmarty, C.J.; McIntyre, P.B.; Gessner, M.O.; Dudgeon, D.; Prusevich, A.; Green, P.; Glidden, S.; Bunn, S.E.; Sullivan, C.A.; Liermann, C.R.; et al. Global threats to human water security and river biodiversity. Nature 2010, 467, 555–561. [Google Scholar] [CrossRef]
  84. Hoekstra, A.Y. The Water Footprint of Modern Consumer Society; Routledge: London, UK, 2013. [Google Scholar]
  85. Hogeboom, R.J.; de Bruin, D.; Schyns, J.F.; Krol, M.S.; Hoekstra, A.Y. Capping human water footprints in the world’s river basins. Earth’s Future 2020, 8, e2019EF001363. [Google Scholar] [CrossRef]
  86. Zhuo, L.; Hoekstra, A.Y.; Wu, P.; Zhao, X. Monthly blue water footprint caps in a river basin to achieve sustainable water consumption: The role of reservoirs. Sci. Total Environ. 2019, 650, 891–899. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  87. Mekonnen, M.M.; Hoekstra, A.Y. Water footprint benchmarks for crop production: A first global assessment. Ecol. Indic. 2014, 46, 214–223. [Google Scholar] [CrossRef] [Green Version]
  88. Zhuo, L.; Mekonnen, M.M.; Hoekstra, A.Y. Benchmark levels for the consumptive water footprint of crop production for different environmental conditions: A case study for winter wheat in China. Hydrol. Earth Syst. Sci. 2016, 20, 4547–4559. [Google Scholar] [CrossRef] [Green Version]
  89. Chukalla, A.D.; Krol, M.S.; Hoekstra, A.Y. Green and blue water footprint reduction in irrigated agriculture: Effect of irrigation techniques, irrigation strategies and mulching. Hydrol. Earth Syst. Sci. 2015, 19, 4877–4891. [Google Scholar] [CrossRef] [Green Version]
  90. Mekonnen, M.M.; Hoekstra, A.Y.; Neale, C.M.U.; Ray, C.; Yang, H.S. Water productivity benchmarks: The case of maize and soybean in Nebraska. Agric. Water Manage. 2020, 234, 106122. [Google Scholar] [CrossRef]
  91. Hoekstra, A.Y. Sustainable, efficient, and equitable water use: The three pillars under wise freshwater allocation. Wiley Interdiscip. Rev. Water 2014, 1, 31–40. [Google Scholar] [CrossRef]
  92. West, P.C.; Gerber, J.S.; Engstrom, P.M.; Mueller, N.D.; Brauman, K.A.; Carlson, K.M.; Cassidy, E.S.; Johnston, M.; MacDonald, G.K.; Ray, D.K.; et al. Leverage points for improving global food security and the environment. Science 2014, 345, 325–328. [Google Scholar] [CrossRef] [Green Version]
  93. Lowe, B.H.; Oglethorpe, D.R.; Choudhary, S. Marrying unmarried literatures: The water footprint and environmental (economic) valuation. Water 2018, 10, 1815. [Google Scholar] [CrossRef] [Green Version]
  94. Cazcarro, I.; Bielsa, J. Blind spots in water management, and how natural sciences could be much more relevant. Front. Plant Sci. 2020, 10. [Google Scholar] [CrossRef]
Water 12 02696 g001 550
Figure 1. The total (green, blue, and grey) WF of food crops production. The WF of fiber crops, rubber, tobacco, and fodder crops is excluded. The pie chart shows the contribution of countries to total WF. Data source from Mekonnen and Hoekstra [29].
Figure 1. The total (green, blue, and grey) WF of food crops production. The WF of fiber crops, rubber, tobacco, and fodder crops is excluded. The pie chart shows the contribution of countries to total WF. Data source from Mekonnen and Hoekstra [29].
Water 12 02696 g001
Water 12 02696 g002 550
Figure 2. The WF of selected crop and animal products: (a) WF in a liter of water per kg of product, (b) WF in a liter of water per kcal of nutritional energy contained in the product. Data source from Mekonnen and Hoekstra [29] and Mekonnen and Hoekstra [37].
Figure 2. The WF of selected crop and animal products: (a) WF in a liter of water per kg of product, (b) WF in a liter of water per kcal of nutritional energy contained in the product. Data source from Mekonnen and Hoekstra [29] and Mekonnen and Hoekstra [37].
Water 12 02696 g002
Water 12 02696 g003 550
Figure 3. The unsustainable blue WF related to crop production: (a) Contribution of different crops toward the global blue unsustainable blue WF of crop production; (b) location of the unsustainable blue WF of crop production. Data source from Mekonnen and Hoekstra [81].
Figure 3. The unsustainable blue WF related to crop production: (a) Contribution of different crops toward the global blue unsustainable blue WF of crop production; (b) location of the unsustainable blue WF of crop production. Data source from Mekonnen and Hoekstra [81].
Water 12 02696 g003
Water 12 02696 g004 550
Figure 4. The sustainable (green) and unsustainable (yellow to dark red) parts of the blue WF of global cereals production. Data source from Mekonnen and Hoekstra [81].
Figure 4. The sustainable (green) and unsustainable (yellow to dark red) parts of the blue WF of global cereals production. Data source from Mekonnen and Hoekstra [81].
Water 12 02696 g004
Table
Table 1. Estimates of the consumptive water footprint (WF) of global crop production.
Table 1. Estimates of the consumptive water footprint (WF) of global crop production.
StudyPeriodProducts CoverageGlobal Water Footprint Related to Crop Production (km3/year)
GreenBlueTotal
Hoekstra and Chapagain [32]1997–2001164 individual crops533010606390
Siebert and Döll [24]1998–200220 individual crops and 6 major groups550511806685
Liu and Yang [25]1998–200217 individual crops and 5 major groups49879515938
Hanasaki, Inuzuka, Kanae and Oki [27]1985–1999Assumed 1 major crop per grid555015307080
Fader, Gerten, Thammer, Heinke, Lotze-Campen, Lucht and Cramer [28]1998–200212 crop functional types60009236923
Mekonnen and Hoekstra [29]1996–2005146 individual crops57718996670
Rost, Gerten, Bondeau, Lucht, Rohwer and Schaphoff [30]1971–200012 crop functional types7250 1600–12587850–8508 1
Huang, Hejazi, Tang, Vernon, Liu, Chen and Calvin [31]1971–2000 488711216008
2071–209912 crop categories544019097349
1 Total evapotranspiration from cropland, including the non-growing period.

Share and Cite

MDPI and ACS Style

Mekonnen, M.M.; Gerbens-Leenes, W. The Water Footprint of Global Food Production. Water 2020, 12, 2696. https://doi.org/10.3390/w12102696

AMA Style

Mekonnen MM, Gerbens-Leenes W. The Water Footprint of Global Food Production. Water. 2020; 12(10):2696. https://doi.org/10.3390/w12102696

Chicago/Turabian Style

Mekonnen, Mesfin M., and Winnie Gerbens-Leenes. 2020. "The Water Footprint of Global Food Production" Water 12, no. 10: 2696. https://doi.org/10.3390/w12102696

APA Style

Mekonnen, M. M., & Gerbens-Leenes, W. (2020). The Water Footprint of Global Food Production. Water, 12(10), 2696. https://doi.org/10.3390/w12102696

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop