The water footprint of humanity
28 Feb 2012-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 109, Iss: 9, pp 3232-3237
TL;DR: The study illustrates the global dimension of water consumption and pollution by showing that several countries heavily rely on foreign water resources and that many countries have significant impacts on water consumptionand pollution elsewhere.
Abstract: This study quantifies and maps the water footprint (WF) of humanity at a high spatial resolution. It reports on consumptive use of rainwater (green WF) and ground and surface water (blue WF) and volumes of water polluted (gray WF). Water footprints are estimated per nation from both a production and consumption perspective. International virtual water flows are estimated based on trade in agricultural and industrial commodities. The global annual average WF in the period 1996–2005 was 9,087 Gm3/y (74% green, 11% blue, 15% gray). Agricultural production contributes 92%. About one-fifth of the global WF relates to production for export. The total volume of international virtual water flows related to trade in agricultural and industrial products was 2,320 Gm3/y (68% green, 13% blue, 19% gray). The WF of the global average consumer was 1,385 m3/y. The average consumer in the United States has a WF of 2,842 m3/y, whereas the average citizens in China and India have WFs of 1,071 and 1,089 m3/y, respectively. Consumption of cereal products gives the largest contribution to the WF of the average consumer (27%), followed by meat (22%) and milk products (7%). The volume and pattern of consumption and the WF per ton of product of the products consumed are the main factors determining the WF of a consumer. The study illustrates the global dimension of water consumption and pollution by showing that several countries heavily rely on foreign water resources and that many countries have significant impacts on water consumption and pollution elsewhere.
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TL;DR: It is found that two-thirds of the global population (4.0 billion people) live under conditions of severe water scarcity at least 1 month of the year, and nearly half of those people live in India and China.
Abstract: Freshwater scarcity is increasingly perceived as a global systemic risk. Previous global water scarcity assessments, measuring water scarcity annually, have underestimated experienced water scarcity by failing to capture the seasonal fluctuations in water consumption and availability. We assess blue water scarcity globally at a high spatial resolution on a monthly basis. We find that two-thirds of the global population (4.0 billion people) live under conditions of severe water scarcity at least 1 month of the year. Nearly half of those people live in India and China. Half a billion people in the world face severe water scarcity all year round. Putting caps to water consumption by river basin, increasing water-use efficiencies, and better sharing of the limited freshwater resources will be key in reducing the threat posed by water scarcity on biodiversity and human welfare.
2,944 citations
Cites methods from "The water footprint of humanity"
...Mekonnen and Hoekstra Sci. Adv....
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...Average monthly blue water footprints at a 5 × 5 arc min resolution for the period 1996–2005 were derived from Mekonnen and Hoekstra (40, 41) and were aggregated to a 30 × 30 arc min resolution....
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...E-mail: m.m.mekonnen@utwente.nl Mekonnen and Hoekstra Sci. Adv....
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...In the latter two countries, it concerns all people in the country, which puts those Mekonnen and Hoekstra Sci. Adv....
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...Only in times wherein water demand and availability Mekonnen and Hoekstra Sci. Adv....
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TL;DR: The ReCiPe2016 method as discussed by the authors provides a state-of-the-art method to convert life cycle inventories to a limited number of life cycle impact scores on midpoint and endpoint level.
Abstract: Life cycle impact assessment (LCIA) translates emissions and resource extractions into a limited number of environmental impact scores by means of so-called characterisation factors. There are two mainstream ways to derive characterisation factors, i.e. at midpoint level and at endpoint level. To further progress LCIA method development, we updated the ReCiPe2008 method to its version of 2016. This paper provides an overview of the key elements of the ReCiPe2016 method. We implemented human health, ecosystem quality and resource scarcity as three areas of protection. Endpoint characterisation factors, directly related to the areas of protection, were derived from midpoint characterisation factors with a constant mid-to-endpoint factor per impact category. We included 17 midpoint impact categories. The update of ReCiPe provides characterisation factors that are representative for the global scale instead of the European scale, while maintaining the possibility for a number of impact categories to implement characterisation factors at a country and continental scale. We also expanded the number of environmental interventions and added impacts of water use on human health, impacts of water use and climate change on freshwater ecosystems and impacts of water use and tropospheric ozone formation on terrestrial ecosystems as novel damage pathways. Although significant effort has been put into the update of ReCiPe, there is still major improvement potential in the way impact pathways are modelled. Further improvements relate to a regionalisation of more impact categories, moving from local to global species extinction and adding more impact pathways. Life cycle impact assessment is a fast evolving field of research. ReCiPe2016 provides a state-of-the-art method to convert life cycle inventories to a limited number of life cycle impact scores on midpoint and endpoint level.
1,624 citations
Cites background or methods from "The water footprint of humanity"
...For industry and domestic water use, assumptions were made based on Hoekstra and Mekonnen (2012)....
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...…et al. 2013; Curran et al. 2014 Water use Increase of water consumed Water consumption potential (WCP) m3 water-eq consumed Döll and Siebert 2002; Hoekstra and Mekonnen 2012 Mineral resource scarcity Increase of ore extracted Surplus ore potential (SOP) kg Cu-eq Vieira et al. 2016a Fossil…...
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TL;DR: The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale and can be combined with the water footprint and virtual water calculations, and be used to assess the potential for increasing agricultural yields with renewable groundwater.
Abstract: A newly developed concept called ‘groundwater footprint’ is used to reveal the degree of sustainable use of global aquifers by calculating the area relative to the extractive demands; globally, this footprint exceeds aquifer area by a factor of about 3.5, and excess withdrawal is centred on just a few agriculturally important aquifers. In many parts of the world, groundwater is being extracted for agricultural use and human consumption at a greater rate than the Earth's natural systems can replace it. Tom Gleeson and colleagues estimate the true scale of the problem using a newly developed concept called the 'groundwater footprint' — defined as the area required to sustain groundwater use and groundwater-dependent ecosystem services. The authors find that globally, the groundwater footprint exceeds the aquifer area by a factor of about 3.5. Overexploitation centres predominantly on a few agriculturally important aquifers in arid or semiarid climates, especially in Asia and North America. The groundwater footprint could serve as a useful framework for analysing the global groundwater depletion data sets emerging from NASA's GRACE satellites. Groundwater is a life-sustaining resource that supplies water to billions of people, plays a central part in irrigated agriculture and influences the health of many ecosystems1,2. Most assessments of global water resources have focused on surface water3,4,5,6, but unsustainable depletion of groundwater has recently been documented on both regional7,8 and global scales9,10,11. It remains unclear how the rate of global groundwater depletion compares to the rate of natural renewal and the supply needed to support ecosystems. Here we define the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services) and show that humans are overexploiting groundwater in many large aquifers that are critical to agriculture, especially in Asia and North America. We estimate that the size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers and that about 1.7 billion people live in areas where groundwater resources and/or groundwater-dependent ecosystems are under threat. That said, 80 per cent of aquifers have a groundwater footprint that is less than their area, meaning that the net global value is driven by a few heavily overexploited aquifers. The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale. It can be combined with the water footprint and virtual water calculations12,13,14, and be used to assess the potential for increasing agricultural yields with renewable groundwaterref15. The method could be modified to evaluate other resources with renewal rates that are slow and spatially heterogeneous, such as fisheries, forestry or soil.
1,070 citations
07 Apr 2016
TL;DR: In this paper, the authors explore and discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner and recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter-and transdisciplinary studies on SDGs related to food security
Abstract: . In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally (vii) all this is only possible if researchers, with soil scientists in the front lines, look over the hedge towards other disciplines, to the world at large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.
1,010 citations
Cites background from "The water footprint of humanity"
...It is estimated that 74 % of all freshwater appropriated by humans comes from the soil (Hoekstra and Mekonnen, 2012)....
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...Agriculture amounts to 92 % of the globe’s freshwater use, far ahead of industrial and domestic usage (Hoekstra and Mekonnen, 2012)....
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United Nations Environment Programme1, Dalhousie University2, Queen's University3, Bedford Institute of Oceanography4, American Museum of Natural History5, BirdLife International6, University of Paris-Sud7, Netherlands Environmental Assessment Agency8, United Nations9, Utrecht University10, University of British Columbia11, Organisation for Economic Co-operation and Development12, The Lodge13, Marine Stewardship Council14, Global Biodiversity Information Facility15, University of Wisconsin-Madison16, University of Queensland17, Zoological Society of London18, Martin Luther University of Halle-Wittenberg19, International Union for Conservation of Nature and Natural Resources20, College of William & Mary21, Sapienza University of Rome22, University of Sussex23, Environment Agency24, University of Vienna25, Microsoft26
TL;DR: A comprehensive mid-term assessment of progress toward 20 biodiversity-related “Aichi Targets” to be achieved within a decade is provided using 55 indicator data sets and pinpoints the problems and areas that will need the most attention in the next few years.
Abstract: In 2010, the international community, under the auspices of the Convention on Biological Diversity, agreed on 20 biodiversity-related “Aichi Targets” to be achieved within a decade. We provide a comprehensive mid-term assessment of progress toward these global targets using 55 indicator data sets. We projected indicator trends to 2020 using an adaptive statistical framework that incorporated the specific properties of individual time series. On current trajectories, results suggest that despite accelerating policy and management responses to the biodiversity crisis, the impacts of these efforts are unlikely to be reflected in improved trends in the state of biodiversity by 2020. We highlight areas of societal endeavor requiring additional efforts to achieve the Aichi Targets, and provide a baseline against which to assess future progress.
970 citations
References
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TL;DR: Numerical experiments combining climate model outputs, water budgets, and socioeconomic information along digitized river networks demonstrate that (i) a large proportion of the world's population is currently experiencing water stress and (ii) rising water demands greatly outweigh greenhouse warming in defining the state of global water systems to 2025.
Abstract: The future adequacy of freshwater resources is difficult to assess, owing to a complex and rapidly changing geography of water supply and use. Numerical experiments combining climate model outputs, water budgets, and socioeconomic information along digitized river networks demonstrate that (i) a large proportion of the world's population is currently experiencing water stress and (ii) rising water demands greatly outweigh greenhouse warming in defining the state of global water systems to 2025. Consideration of direct human impacts on global water supply remains a poorly articulated but potentially important facet of the larger global change question.
4,355 citations
"The water footprint of humanity" refers background in this paper
...The WFs within nations related to water use in livestock farming were obtained from Mekonnen and Hoekstra (23)....
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...The WFs within nations related to crop production were obtained from Mekonnen and Hoekstra (21, 22, 36), who estimated the global WF of crop production with a crop water use model at a 5 × 50 spatial resolution....
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...The WFs of agricultural products were taken from Mekonnen and Hoekstra (5, 6)....
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TL;DR: In this article, the authors used a grid-based dynamic water balance model to estimate the green, blue and grey water footprint of global crop production in a spatially-explicit way for the period 1996-2005.
Abstract: This study quantifies the green, blue and grey water footprint of global crop production in a spatially-explicit way for the period 1996–2005. The assessment improves upon earlier research by taking a high-resolution approach, estimating the water footprint of 126 crops at a 5 by 5 arc minute grid. We have used a grid-based dynamic water balance model to calculate crop water use over time, with a time step of one day. The model takes into account the daily soil water balance and climatic conditions for each grid cell. In addition, the water pollution associated with the use of nitrogen fertilizer in crop production is estimated for each grid cell. The crop evapotranspiration of additional 20 minor crops is calculated with the CROPWAT model. In addition, we have calculated the water footprint of more than two hundred derived crop products, including various flours, beverages, fibres and biofuels. We have used the water footprint assessment framework as in the guideline of the Water Footprint Network.
Considering the water footprints of primary crops, we see that the global average water footprint per ton of crop increases from sugar crops (roughly 200 m3 ton−1), vegetables (300 m3 ton−1), roots and tubers (400 m3 ton−1), fruits (1000 m3 ton−1), cereals (1600 m3 ton−1), oil crops (2400 m3 ton−1) to pulses (4000 m3 ton−1). The water footprint varies, however, across different crops per crop category and per production region as well. Besides, if one considers the water footprint per kcal, the picture changes as well. When considered per ton of product, commodities with relatively large water footprints are: coffee, tea, cocoa, tobacco, spices, nuts, rubber and fibres. The analysis of water footprints of different biofuels shows that bio-ethanol has a lower water footprint (in m3 GJ−1) than biodiesel, which supports earlier analyses. The crop used matters significantly as well: the global average water footprint of bio-ethanol based on sugar beet amounts to 51 m3 GJ−1, while this is 121 m3 GJ−1 for maize.
The global water footprint related to crop production in the period 1996–2005 was 7404 billion cubic meters per year (78 % green, 12 % blue, 10 % grey). A large total water footprint was calculated for wheat (1087 Gm3 yr−1), rice (992 Gm3 yr−1) and maize (770 Gm3 yr−1). Wheat and rice have the largest blue water footprints, together accounting for 45 % of the global blue water footprint. At country level, the total water footprint was largest for India (1047 Gm3 yr−1), China (967 Gm3 yr−1) and the USA (826 Gm3 yr−1). A relatively large total blue water footprint as a result of crop production is observed in the Indus river basin (117 Gm3 yr−1) and the Ganges river basin (108 Gm3 yr−1). The two basins together account for 25 % of the blue water footprint related to global crop production. Globally, rain-fed agriculture has a water footprint of 5173 Gm3 yr−1 (91 % green, 9 % grey); irrigated agriculture has a water footprint of 2230 Gm3 yr−1 (48 % green, 40 % blue, 12 % grey).
1,664 citations
TL;DR: The water footprint of a country is defined as the volume of water needed for the production of the goods and services consumed by the inhabitants of the country as mentioned in this paper, which shows the extent of water use in relation to consumption of people.
Abstract: The water footprint shows the extent of water use in relation to consumption of people. The water footprint of a country is defined as the volume of water needed for the production of the goods and services consumed by the inhabitants of the country. The internal water footprint is the volume of water used from domestic water resources; the external water footprint is the volume of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country. The study calculates the water footprint for each nation of the world for the period 1997-2001. The USA appears to have an average water footprint of 2480 m 3 /cap/yr, while China has an average footprint of 700 m 3 /cap/yr. The global average water footprint is 1240 m 3 /cap/yr. The four major direct
1,398 citations
TL;DR: In this paper, the authors show that increased use of evapotranspiration will confer minimal benefits globally because most land suitable for rain-fed agriculture is already in production. And they also show that new dam construction could increase accessible runoff by about 10 percent over the next 30 years, whereas population is projected to increase by more than 45 percent during that period.
Abstract: Humanity now uses 26 percent of total terrestrial evapotranspiration and 54 percent of runoff that is geographically and temporally accessible. Increased use of evapotranspiration will confer minimal benefits globally because most land suitable for rain-fed agriculture is already in production. New dam construction could increase accessible runoff by about 10 percent over the next 30 years, whereas population is projected to increase by more than 45 percent during that period.
1,355 citations
"The water footprint of humanity" refers background in this paper
...The WFs within nations related to water use in livestock farming were obtained from Mekonnen and Hoekstra (23)....
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...The WFs within nations related to crop production were obtained from Mekonnen and Hoekstra (21, 22, 36), who estimated the global WF of crop production with a crop water use model at a 5 × 50 spatial resolution....
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...The WFs of agricultural products were taken from Mekonnen and Hoekstra (5, 6)....
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01 Jan 2003
852 citations
"The water footprint of humanity" refers background or methods in this paper
...An earlier global study on the WFs of nations was carried out by Hoekstra and Hung (16); another, much more comprehensive study, was done by Hoekstra and Chapagain and reported in a number of subsequent publications (8, 17–20)....
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...Finally, we apply the bottom-up approach in estimating the WF of national consumption of agricultural products, which is less sensitive to trade data than the top-down approach that was applied in the earlier studies (8, 16)....
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...Hoekstra AY, Hung PQ (2002) Virtual water trade: A quantification of virtual water flows between nations in relation to international crop trade....
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...Hoekstra AY, Hung PQ (2005) Globalisation of water resources: International virtual water flows in relation to crop trade....
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...The current study is more comprehensive and detailed than the earlier two global WF studies (8, 16)....
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