Global gray water footprint and water pollution levels related to anthropogenic nitrogen loads to fresh water

This is the first global assessment of nitrogen-related water pollution in river basins with a specification of the pollution by economic sector, and by crop for the agricultural sector. At a spatial resolution of 5 by 5 arc minute, we estimate anthropogenic nitrogen (N) loads to freshwater, calculate the resultant gray water footprints (GWFs), and relate the GWFs per river basin to runoff to calculate the N-related water pollution level (WPL) per catchment. The accumulated global GWF related to anthropogenic N loads in the period 2002–2010 was 13 × 1012 m3/y. China contributed about 45% to the global total. Three quarters of the GWF related to N loads came from diffuse sources (agriculture), 23% from domestic point sources and 2% from industrial point sources. Among the crops, production of cereals had the largest contribution to the N-related GWF (18%), followed by vegetables (15%) and oil crops (11%). The river basins with WPL > 1 (where the N load exceeds the basin’s assimilation capacity), cover about 17% of the global land area, contribute about 9% of the global river discharge, and provide residence to 48% of the global population

The green, blue and grey water footprint of farm animals and animal products. Volume 1: Main Report

The projected increase in the production and consumption of animal products is likely to put further pressure on the globe’s freshwater resources. The size and characteristics of the water footprint vary across animal types and production systems. The current study provides a comprehensive account of the global green, blue and grey water footprints of different sorts of farm animals and animal products, distinguishing between different production systems and considering the conditions in all countries of the world separately. The following animal categories were considered: beef cattle, dairy cattle, pig, sheep, goat, broiler chicken, layer chicken and horses. The study shows that the water footprint of meat from beef cattle (15400 m3/ton as a global average) is much larger than the footprints of meat from sheep (10400 m3/ton), pig (6000 m3/ton), goat (5500 m3/ton) or chicken (4300 m3/ton). The global average water footprint of chicken egg is 3300 m3/ton, while the water footprint of cow milk amounts to 1000 m3/ton. Per ton of product, animal products generally have a larger water footprint than crop products. The same is true when we look at the water footprint per calorie. The average water footprint per calorie for beef is twenty times larger than for cereals and starchy roots. When we look at the water requirements for protein, we find that the water footprint per gram of protein for milk, eggs and chicken meat is about 1.5 times larger than for pulses. For beef, the water footprint per gram of protein is 6 times larger than for pulses. In the case of fat, we find that butter has a relatively small water footprint per gram of fat, even lower than for oil crops. All other animal products, however, have larger water footprints per gram of fat when compared to oil crops. The study shows that from a freshwater resource perspective, it is more efficient to obtain calories, protein and fat through crop products than animal products. Global animal production requires about 2422 Gm3 of water per year (87.2% green, 6.2% blue, 6.6% grey water). One third of this volume is for the beef cattle sector; another 19% for the dairy cattle sector. Most of the total volume of water (98%) refers to the water footprint of the feed for the animals. Drinking water for the animals, service water and feed mixing water account only for 1.1%, 0.8% and 0.03%, respectively. The water footprints of animal products can be understood from three main factors: feed conversion efficiency of the animal, feed composition, and origin of the feed. The type of production system (grazing, mixed, industrial) is important because it influences all three factors. A first explanatory factor in the water footprints of animal products is the feed conversion efficiency. The more feed is required per unit of animal product, the more water is necessary (to produce the feed). The unfavourable feed conversion efficiency for beef cattle is largely responsible for the relatively large water footprint of beef. Sheep and goats have an unfavourable feed conversion efficiency as well, although better than cattle. A second factor is the feed composition, in particular the ratio of concentrates versus roughages and the percentage of valuable crop components versus crop residues in the concentrate. Chicken and pig have relatively large fractions of cereals and oil meal in their feed, which results in relatively large water footprints of their feed and abolishes the effect of the favourable feed conversion efficiencies. A third factor that influences the water footprint of an animal product is the origin of the feed. The water footprint of a specific animal product varies across countries due to differences in climate and agricultural practice in the regions from where the various feed components are obtained. Since sometimes a relatively large fraction of the feed is imported while at other times feed is mostly obtained locally, not only the size but also the spatial dimension of the water footprint depends on the sourcing of the feed

National water footprint accounts: The green, blue and grey water footprint of production and consumption. Volume 2: Appendices

Contents Appendix I. The water footprint of national production (Mm3/yr) Appendix II. Virtual-water flows related to trade in crop, animal and industrial products, per country (Mm3/yr) Appendix III. International virtual-water flows per product category (Mm3/yr) Appendix IV. National water saving related to trade in agricultural and industrial products per country (Mm3/yr) Appendix V. Global water saving related to trade in agricultural and industrial products, per product (Mm3/yr) Appendix VI. The average water footprint per ton of commodity per country, weighted based on origin (WF* in m3/ton) Appendix VII. The water footprint of national consumption per capita, shown by commodity (m3/yr/cap) Appendix VIII. The water footprint of national consumption per capita, shown by major consumption category and by internal and external component (m3/yr/cap) Appendix IX. The total water footprint of national consumption (Mm3/yr) Appendix X. The water footprint of US consumption of agricultural and industrial products, specified per river basin (m3/yr) Appendix XI. The global water footprint of national consumption: maps for selected countrie

The green, blue and grey water footprint of farm animals and animal products. Volume 2: Appendices

Contents Appendix I: Feed conversion efficiencies – in kg of feed (dry mass) per kg of output – per animal category and region Appendix II: Estimated consumption of feed per animal category and world region (103 ton dry mass/yr) Appendix III. Estimated consumption of feed per production system and world region (103 ton dry mass/yr) Appendix IV. Drinking and service water footprint per animal Appendix V. Water footprint of animals and animal products (m3/ton). Period 1996-200

National water footprint accounts: The green, blue and grey water footprint of production and consumption. Volume 1: Main Report

This study quantifies and maps the water footprints of nations from both a production and consumption perspective and estimates international virtual water flows and national and global water savings as a result of trade. The entire estimate includes a breakdown of water footprints, virtual water flows and water savings into their green, blue and grey components. The main finding of the study can be summarized as: The global water footprint in the period 1996-2005 was 9087 Gm3/yr (74% green, 11% blue, 15% grey). Agricultural production contributes 92% to this total footprint. About one fifth of the global water footprint relates to production for export. The total volume of international virtual water flows related to trade in agricultural and industrial products was 2320 Gm3/yr (68% green, 13% blue, 19% grey). Trade in crop products contributes 76% to the total volume of international virtual water flows; trade in animal and industrial products contribute 12% each. As a global average, the blue and grey shares in the total water footprint of internationally traded products are slightly larger than in the case of domestically consumed products. Mexico and Spain are the two countries with the largest national blue water savings as a result of trade. The global water saving as a result of trade in agricultural products in the period 1996-2005 was 369 Gm3/yr (59% green, 27% blue, 15% grey), which is equivalent to 4% of the global water footprint related to agricultural production. The global blue water saving is equivalent to 10% of the global blue water footprint related to agricultural production, which indicates that virtual water importing countries generally depend more strongly on blue water for crop production than the virtual water exporting countries. The largest global water saving (53%) is due to trade in cereal crops, followed by oil crops (22%) and animal products (15%). International trade in industrial products can be associated with an increased global water footprint that is equivalent to 4% of the global water footprint related to industrial production. The water footprint of the global average consumer in the period 1996-2005 was 1385 m3/yr. About 92% of the water footprint is related to the consumption of agricultural products, 5% to the consumption of industrial goods, and 4% to domestic water use. The average consumer in the US has a water footprint of 2842 m3/yr, while the average citizens in China and India have water footprints of 1071 m3/yr and 1089 m3/yr respectively. Consumption of cereal products gives the largest contribution to the water footprint of the average consumer (27%), followed by meat (22%) and milk products (7%). The contribution of different consumption categories to the total water footprint varies across countries. The volume and pattern of consumption and the water footprint per ton of product of the products consumed are the main factors determining the water footprint of a consumer. The study illustrates the global dimension of water consumption and pollution by showing that several countries heavily rely on water resources elsewhere (for example Mexico depending on virtual water imports from the US) and that many countries have significant impacts on water consumption and pollution elsewhere (for example Japan and many European countries due to their large external water footprints)

The water footprint of global food production

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

The water footprint assessment manual: setting the global standard

This book contains the global standard for \u27water footprint assessment\u27 as developed and maintained by the Water Footprint Network (WFN). It covers a comprehensive set of definitions and methods for water footprint accounting. It shows how water footprints are calculated for individual processes and products, as well as for consumers, nations and businesses. It also includes methods for water footprint sustainability assessment and a library of water footprint response options. A shared standard on definitions and calculation methods is crucial given the rapidly growing interest in companies and governments to use water footprint accounts as a basis for formulating sustainable water strategies and policies

Anthropogenic nitrogen and phosphorus emissions and related grey water footprints caused by EU-27's crop production and consumption

Water is a prerequisite for life on our planet. Due to climate change and pollution, water availability for agricultural production, industry and households is increasingly put at risk. With agriculture being the largest water user as well as polluter worldwide, we estimate anthropogenic nitrogen and phosphorus emissions to fresh water related to global crop production at a spatial resolution level of 5 by 5 arc min and calculate the grey water footprints (GWF) related to EU-27′s crop production. A multiregional input-output model is used to trace the the GWF embodied in the final consumption of crop products by the EU-27. The total GWF related to crop production in the EU-27 in 2007 was 1 × 1012 m3/year. Spain contributed about 40% to this total. Production of cereals (wheat, rice and other cereals) take the largest share, accounting for 30% of the GWF, followed by fruits (17%), vegetables (14%), and oil crops (13%). The total agricultural GWF of the EU-27 related to crop consumption was 1830 billion m3/year, which is 3700 m3/year per capita on average. Overall, the EU-27 was able to externalize about 41% of the GWF to the rest of the world through imports of crop product

The effect of inter-annual variability of consumption, production, trade and climate on crop-related green and blue water footprints and inter-regional virtual water trade: A study for China (1978–2008)

AbstractPrevious studies into the relation between human consumption and indirect water resources use have unveiled the remote connections in virtual water (VW) trade networks, which show how communities externalize their water footprint (WF) to places far beyond their own region, but little has been done to understand variability in time. This study quantifies the effect of inter-annual variability of consumption, production, trade and climate on WF and VW trade, using China over the period 1978–2008 as a case study. Evapotranspiration, crop yields and green and blue WFs of crops are estimated at a 5 × 5 arc-minute resolution for 22 crops, for each year in the study period, thus accounting for climate variability. The results show that crop yield improvements during the study period helped to reduce the national average WF of crop consumption per capita by 23%, with a decreasing contribution to the total from cereals and increasing contribution from oil crops. The total consumptive WFs of national crop consumption and crop production, however, grew by 6% and 7%, respectively. By 2008, 28% of total water consumption in crop fields in China served the production of crops for export to other regions and, on average, 35% of the crop-related WF of a Chinese consumer was outside its own province. Historically, the net VW within China was from the water-rich South to the water-scarce North, but intensifying North-to-South crop trade reversed the net VW flow since 2000, which amounted 6% of North's WF of crop production in 2008. South China thus gradually became dependent on food supply from the water-scarce North. Besides, during the whole study period, China's domestic inter-regional VW flows went dominantly from areas with a relatively large to areas with a relatively small blue WF per unit of crop, which in 2008 resulted in a trade-related blue water loss of 7% of the national total blue WF of crop production. The case of China shows that domestic trade, as governed by economics and governmental policies rather than by regional differences in water endowments, determines inter-regional water dependencies and may worsen rather than relieve the water scarcity in a country

Anthropogenic Nitrogen and Phosphorus Emissions and Related Grey Water Footprints Caused by EU-27's Crop Production and Consumption

Water is a prerequisite for life on our planet. Due to climate change and pollution, water availability for agricultural production, industry and households is increasingly put at risk. With agriculture being the largest water user as well as polluter worldwide, we estimate anthropogenic nitrogen and phosphorus emissions to fresh water related to global crop production at a spatial resolution level of 5 by 5 arc min and calculate the grey water footprints (GWF) related to EU-27's crop production. A multiregional input-output model is used to trace the the GWF embodied in the final consumption of crop products by the EU-27. The total GWF related to crop production in the EU-27 in 2007 was 1 × 1012 m3/year. Spain contributed about 40% to this total. Production of cereals (wheat, rice and other cereals) take the largest share, accounting for 30% of the GWF, followed by fruits (17%), vegetables (14%), and oil crops (13%). The total agricultural GWF of the EU-27 related to crop consumption was 1830 billion m3/year, which is 3700 m3/year per capita on average. Overall, the EU-27 was able to externalize about 41% of the GWF to the rest of the world through imports of crop products