ArticlePublisher preview available

The water footprint of different diets within European sub-national geographical entities

September 2018
Nature Sustainability 1(9)

DOI:10.1038/s41893-018-0133-x

Authors:

Davy Vanham

Sara Comero

University of Milan

Bernd Manfred Gawlik

European Commission

Giovanni Bidoglio

European Commission

The water footprint concept has been recognized as being highly valuable for raising awareness of the large quantity of water resources required to produce the food we consume. We present, for three major European countries (the United Kingdom, France and Germany), a geographically detailed nationwide food-consumption-related water footprint, taking into account socio-economic factors of food consumption, for both existing and recommended diets (healthy diet with meat, healthy pescetarian diet and healthy vegetarian diet). Using socio-economic data, national food surveys and international food consumption and water footprint databases, we were able to refine national water footprint data to the smallest possible administrative boundaries within a country (reference period 2007–2011). We found geographical differences in water footprint values for existing diets as well as for the reduction in water footprints associated with a change to the recommended healthy diets. For all 43,786 analysed geographical entities, the water footprint decreases for a healthy diet containing meat (range 11–35%). Larger reductions are observed for the healthy pescetarian (range 33–55%) and healthy vegetarian (range 35–55%) diets. In other words, shifting to a healthy diet is not only good for human health, but also substantially reduces consumption of water resources, consistently for all geographical entities throughout the three countries. Our full results are available as a supplementary dataset. These data can be used at different governance levels in order to inform policies targeted to specific geographical entities. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.

| The relationship between socio-economic factors and the WF of food product groups. a, In French municipalities, the WF of milk consumption decreases with average age. b, In London (983 geographical entities), there is a strong correlation (0.94) between the WF of wine consumption and the percentage of population with a high education level.

…

The total water footprint related to food consumption a–c, Interval of values according to frequency (that is, 0–10%, 10–25%, 25–50%, 50–75%, 75–100%) for France (a), the United Kingdom (b) and Germany (c). d,The relationship between the log of the population (x axis) and the ratio between the computed local and national water footprints (y axis) for all three countries combined. With increasing population size, the s.d. of this ratio decreases. In other words, the smaller the population size of the geographical entity, the more the water footprint can deviate from the national average value.

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Reduction in the total water footprint related to food consumption for a healthy diet containing meat (HEALTHY-MEAT) a–c, Interval of values according to frequency (that is, 0–10%, 10–25%, 25–50%, 50–75%, 75–100%) for Germany (a), France (b) and the United Kingdom (c). The upper maps present normal geographical projections, and the lower maps are cartograms⁵⁰ according to population sizes of the geographical entities.

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Reduction in the water footprint of specific food product group consumption, for a healthy diet containing meat a,b, Interval of values according to population-weighted frequency (that is, 0–10%, 10–25%, 25–50%, 50–75%, 75–100%) for meat (a) and oils and fats (b). The maps are cartograms⁵⁰ according to population sizes of the geographical entities.

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Reduction in the total water footprint for a healthy pescetarian diet or a healthy vegetarian diet a,b, Interval of values according to population-weighted frequency (that is, 0–10%, 10–25%, 25–50%, 50–75%, 75–100%) for a healthy pescetarian diet (HEALTHY-PESC) (a) or a healthy vegetarian diet (HEALTHY-VEG) (b). The maps are cartograms⁵⁰ according to population sizes of the geographical entities.

…

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AnAlysis

https://doi.org/10.1038/s41893-018-0133-x

European Commission, Joint Research Centre, Directorate for Sustainable Resources, Ispra, Italy. *e-mail: davy.vanham@ec.europa.eu

Water is an essential resource in meeting the Sustainable

Development Goals of water, food and energy security1.

Due to human freshwater use in different economic

activities, both blue (surface and groundwater) and green (soil

moisture) water resources are considered scarce2,3. Competition

for them will grow due to an increasing global population, shifting

lifestyles and climate change4–8. To achieve global food, water and

energy security, changes along the whole product supply chain are

necessary; that is, from the production to the consumption side. On

the consumption side, this includes dietary behaviour9. The water

footprint (WF) provides the possibility to link water resources to

this consumption side.

The WF is an indicator of freshwater use that looks at both the

direct and indirect water use of a consumer or producer10. It quanti-

fies consumptive water use along a supply chain. We use blue and

green WF components in our assessment. Blue water refers to liq-

uid water in rivers, lakes, wetlands and aquifers. Green water is the

soil water held in the unsaturated zone, formed by precipitation and

available to plants11. Irrigated agriculture receives blue water (from

irrigation) as well as green water (from precipitation), while rain-

fed agriculture receives only green water.

The WF of food consumption including diet scenarios has been

quantified on the national level12,13 and increasingly on geographi-

cally more detailed levels such as cities14,15, but not covering whole

nations to the highest geographical level of detail possible.

Individual food consumption behaviour depends strongly on

socio-economic factors such as age, gender, education level or

income16. Certain detailed food surveys provide such information.

Such detailed surveys are only available in a few countries. In Europe,

this includes France17, Germany18 and the United Kingdom19. On

the geographical level, we looked for the smallest entity where the

combined statistics age, gender and minimum one extra statistic

can be found, nationwide (spanning the whole country). We found

this situation for the statistic ‘highest level of education’, for 34,968

municipalities (including the boroughs of the three metropoli-

tan regions Paris, Lyon and Marseilles) in France, 8,506 statistical

entities in the United Kingdom and 412 districts in Germany. The

municipality is the fourth and lowest tier of governance in France

(after nation, region (Supplementary Fig. 2) and department). The

region level is the highest tier of sub-national division in the United

Kingdom (Supplementary Fig. 3), followed by the county and dis-

trict level, in which our analysed statistical entities fit. Districts are

the third tier of governance in Germany, after the federal and state

levels (Supplementary Fig. 4). The smallest administrative units in

Germany are municipalities.

We first assessed whether food surveys show differences in the

intake of food product groups between regions within a country. As

a second step, we then looked for differences with respect to these

three socio-economic factors (age, gender, education level) within

regions. The first step is important because regional food consump-

tion behaviour can depend on a combination of food availability

and (agricultural) tradition. People in southern Europe, for exam-

ple, consume more olive oil than in northern Europe. The results are

presented in Supplementary Tables 9, 10 and 11.

National food-consumption-related WFs

We compute the following national food-consumption-related

(green + blue) WFs: 2,757 (92% green and 8% blue) litres per capita

per day (l cap−1 d−1) for the United Kingdom, 2,929 (95% green and

5% blue) l cap−1 d−1 for Germany and 3,861 (93% green and 7% blue)

l cap−1 d−1 for France. National food-consumption-related WFs

result from both domestic agricultural and food-processing pro-

duction, as well as food product import. Worldwide, national food-

consumption-related WFs range from 1,493 to 9,899 l cap−1 d−1,

with a global average of 3,167 (88% green and 12% blue) l cap−1 d−1

(ref. 10). As agriculture in these three countries is dominated by

The water footprint of different diets within

European sub-national geographical entities

Davy Vanham *, Sara Comero, Bernd Manfred Gawlik and Giovanni Bidoglio

The water footprint concept has been recognized as being highly valuable for raising awareness of the large quantity of water

resources required to produce the food we consume. We present, for three major European countries (the United Kingdom,

France and Germany), a geographically detailed nationwide food-consumption-related water footprint, taking into account

socio-economic factors of food consumption, for both existing and recommended diets (healthy diet with meat, healthy

pescetarian diet and healthy vegetarian diet). Using socio-economic data, national food surveys and international food con-

sumption and water footprint databases, we were able to refine national water footprint data to the smallest possible adminis-

trative boundaries within a country (reference period 2007–2011). We found geographical differences in water footprint values

for existing diets as well as for the reduction in water footprints associated with a change to the recommended healthy diets.

For all 43,786 analysed geographical entities, the water footprint decreases for a healthy diet containing meat (range 11–35%).

Larger reductions are observed for the healthy pescetarian (range 33–55%) and healthy vegetarian (range 35–55%) diets.

In other words, shifting to a healthy diet is not only good for human health, but also substantially reduces consumption of

water resources, consistently for all geographical entities throughout the three countries. Our full results are available as a

supplementary dataset. These data can be used at different governance levels in order to inform policies targeted to specific

geographical entities.

NATURE SUSTAINABILITY | VOL 1 | SEPTEMBER 2018 | 518–525 | www.nature.com/natsustain

518

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Oct 2017

Background Underweight, overweight, and obesity in childhood and adolescence are associated with adverse health consequences throughout the life-course. Our aim was to estimate worldwide trends in mean body-mass index (BMI) and a comprehensive set of BMI categories that cover underweight to obesity in children and adolescents, and to compare trends with those of adults. Methods We pooled 2416 population-based studies with measurements of height and weight on 128·9 million participants aged 5 years and older, including 31·5 million aged 5–19 years. We used a Bayesian hierarchical model to estimate trends from 1975 to 2016 in 200 countries for mean BMI and for prevalence of BMI in the following categories for children and adolescents aged 5–19 years: more than 2 SD below the median of the WHO growth reference for children and adolescents (referred to as moderate and severe underweight hereafter), 2 SD to more than 1 SD below the median (mild underweight), 1 SD below the median to 1 SD above the median (healthy weight), more than 1 SD to 2 SD above the median (overweight but not obese), and more than 2 SD above the median (obesity). Findings Regional change in age-standardised mean BMI in girls from 1975 to 2016 ranged from virtually no change (–0·01 kg/m² per decade; 95% credible interval –0·42 to 0·39, posterior probability [PP] of the observed decrease being a true decrease=0·5098) in eastern Europe to an increase of 1·00 kg/m² per decade (0·69–1·35, PP>0·9999) in central Latin America and an increase of 0·95 kg/m² per decade (0·64–1·25, PP>0·9999) in Polynesia and Micronesia. The range for boys was from a non-significant increase of 0·09 kg/m² per decade (–0·33 to 0·49, PP=0·6926) in eastern Europe to an increase of 0·77 kg/m² per decade (0·50–1·06, PP>0·9999) in Polynesia and Micronesia. Trends in mean BMI have recently flattened in northwestern Europe and the high-income English-speaking and Asia-Pacific regions for both sexes, southwestern Europe for boys, and central and Andean Latin America for girls. By contrast, the rise in BMI has accelerated in east and south Asia for both sexes, and southeast Asia for boys. Global age-standardised prevalence of obesity increased from 0·7% (0·4–1·2) in 1975 to 5·6% (4·8–6·5) in 2016 in girls, and from 0·9% (0·5–1·3) in 1975 to 7·8% (6·7–9·1) in 2016 in boys; the prevalence of moderate and severe underweight decreased from 9·2% (6·0–12·9) in 1975 to 8·4% (6·8–10·1) in 2016 in girls and from 14·8% (10·4–19·5) in 1975 to 12·4% (10·3–14·5) in 2016 in boys. Prevalence of moderate and severe underweight was highest in India, at 22·7% (16·7–29·6) among girls and 30·7% (23·5–38·0) among boys. Prevalence of obesity was more than 30% in girls in Nauru, the Cook Islands, and Palau; and boys in the Cook Islands, Nauru, Palau, Niue, and American Samoa in 2016. Prevalence of obesity was about 20% or more in several countries in Polynesia and Micronesia, the Middle East and north Africa, the Caribbean, and the USA. In 2016, 75 (44–117) million girls and 117 (70–178) million boys worldwide were moderately or severely underweight. In the same year, 50 (24–89) million girls and 74 (39–125) million boys worldwide were obese. Interpretation The rising trends in children’s and adolescents’ BMI have plateaued in many high-income countries, albeit at high levels, but have accelerated in parts of Asia, with trends no longer correlated with those of adults.

Physical water scarcity metrics for monitoring progress towards SDG target 6.4: An evaluation of indicator 6.4.2 " Level of water stress "

Article

Full-text available

Feb 2018

Target 6.4 of the recently adopted Sustainable Development Goals (SDGs) deals with the reduction of water scarcity. To monitor progress towards this target, two indicators are used: Indicator 6.4.1 measuring water use efficiency and 6.4.2 measuring the level of water stress (WS). This paper aims to identify whether the currently proposed indicator 6.4.2 considers the different elements that need to be accounted for in a WS indicator. WS indicators compare water use with water availability. We identify seven essential elements: 1) both gross and net water abstraction (or withdrawal) provide important information to understand WS; 2) WS indicators need to incorporate environmental flow requirements (EFR); 3) temporal and 4) spatial disaggregation is required in a WS assessment; 5) both renewable surface water and groundwater resources, including their interaction, need to be accounted for as renewable water availability; 6) alternative available water resources need to be accounted for as well, like fossil groundwater and desalinated water; 7) WS indicators need to account for water storage in reservoirs, water recycling and managed aquifer recharge. Indicator 6.4.2 considers many of these elements, but there is need for improvement. It is recommended that WS is measured based on net abstraction as well, in addition to currently only measuring WS based on gross abstraction. It does incorporate EFR. Temporal and spatial disaggregation is indeed defined as a goal in more advanced monitoring levels, in which it is also called for a differentiation between surface and groundwater resources. However, regarding element 6 and 7 there are some shortcomings for which we provide recommendations. In addition, indicator 6.4.2 is only one indicator, which monitors blue WS, but does not give information on green or green-blue water scarcity or on water quality. Within the SDG indicator framework, some of these topics are covered with other indicators.

Drought impacts to water footprints and virtual water transfers of the Central Valley of California

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Full-text available

Jun 2017
WATER RESOUR RES

The Central Valley of California is one of the most productive agricultural locations in the world, which is made possible by a complex and vast irrigation system. Beginning in 2012, California endured one of the worst droughts in its history. Local impacts of the drought have been evaluated, but it is not yet well understood how the drought reverberated through the global food system. Here, we quantify drought impacts to the water footprint (WF) of agricultural production and virtual water transfers (VWT) from the Central Valley of California. To do this, we utilize high-resolution spatial and temporal datasets and a crop model from pre-drought conditions (2011) through three years of exceptional drought (2012-2014). Despite a 12% reduction in harvested area, the WF of agricultural production in the Central Valley increased by 3%. This was due to greater crop water requirements from higher temperatures and a shift to more water-intensive orchard and vine crops. The groundwater WF increased from 7.00 km3 in 2011 to 13.63 km3 in 2014, predominantly in the Tulare Basin. Transfers of food commodities declined by 1% during the drought, yet total VWT increased by 3% (0.51 km3). From 2011 to 2014, groundwater VWT increased by 3.42 km3, offsetting the 0.94 km3 reduction in green VWT and the 1.96 km3 decrease in surface VWT. During the drought, local and global consumers nearly doubled their reliance on the Central Valley Aquifer. These results indicate that drought may strengthen the telecoupling between groundwater withdrawals and distant consumers of agricultural commodities.

Urban Water Atlas for Europe

Book

Full-text available

Apr 2017

How do we manage water in cities? Where does our drinking water come from? Where does our waste water go? How much water do we consume? Is our life-style affecting our water? This first overview of Urban Water Management in Europe explains and illustrates water in an unprecedented way, reflecting how water flows through the arteries of our cities. Informative texts, stunning photographs and fascinating artwork allows us to address and answer these and other questions. Leading experts in water sciences and technologies, together with climate change researchers have teamed up with artists and children in order to show how thirsty our cities really are and how we can cope with their growing demand for the most precious resource of our planet. The Urban Water Atlas for Europe sets the benchmark for 40 European cities, thus helping them to face one of the greatest global challenges with local solutions providing water for all. The Urban Water Atlas for Europe is more than just a normal atlas. It presents water as our unique source of life and as a meeting point between cities. By introducing the emotional aspects of water – as seen through the eyes of children and artists – the Urban Water Atlas for Europe builds bridges between those who constitute Europe; its citizens

Groundwater depletion embedded in international food trade

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Full-text available

Mar 2017

Recent hydrological modelling and Earth observations have located and quantified alarming rates of groundwater depletion worldwide. This depletion is primarily due to water withdrawals for irrigation, but its connection with the main driver of irrigation, global food consumption, has not yet been explored. Here we show that approximately eleven per cent of non-renewable groundwater use for irrigation is embedded in international food trade, of which two-thirds are exported by Pakistan, the USA and India alone. Our quantification of groundwater depletion embedded in the world’s food trade is based on a combination of global, crop-specific estimates of non-renewable groundwater abstraction and international food trade data. A vast majority of the world’s population lives in countries sourcing nearly all their staple crop imports from partners who deplete groundwater to produce these crops, highlighting risks for global food and water security. Some countries, such as the USA, Mexico, Iran and China, are particularly exposed to these risks because they both produce and import food irrigated from rapidly depleting aquifers. Our results could help to improve the sustainability of global food production and groundwater resource management by identifying priority regions and agricultural products at risk as well as the end consumers of these products.

Trends in adult body-mass index in 200 countries from 1975 to 2014: a pooled analysis of 1698 population-based measurement studies with 19·2 million participants

Article

Jan 2016

Background: Underweight and severe and morbid obesity are associated with highly elevated risks of adverse health outcomes. We estimated trends in mean body-mass index (BMI), which characterises its population distribution, and in the prevalences of a complete set of BMI categories for adults in all countries. Methods: We analysed, with use of a consistent protocol, population-based studies that had measured height and weight in adults aged 18 years and older. We applied a Bayesian hierarchical model to these data to estimate trends from 1975 to 2014 in mean BMI and in the prevalences of BMI categories (<18·5 kg/m2 [underweight], 18·5 kg/m2 to <20 kg/m2, 20 kg/m2 to <25 kg/m2, 25 kg/m2 to <30 kg/m2, 30 kg/m2 to <35 kg/m2, 35 kg/m2 to <40 kg/m2, ≥40 kg/m2 [morbid obesity]), by sex in 200 countries and territories, organised in 21 regions. We calculated the posterior probability of meeting the target of halting by 2025 the rise in obesity at its 2010 levels, if post-2000 trends continue. Findings: We used 1698 population-based data sources, with more than 19·2 million adult participants (9·9 million men and 9·3 million women) in 186 of 200 countries for which estimates were made. Global age-standardised mean BMI increased from 21·7 kg/m2 (95% credible interval 21·3–22·1) in 1975 to 24·2 kg/m2 (24·0–24·4) in 2014 in men, and from 22·1 kg/m2 (21·7–22·5) in 1975 to 24·4 kg/m2 (24·2–24·6) in 2014 in women. Regional mean BMIs in 2014 for men ranged from 21·4 kg/m2 in central Africa and south Asia to 29·2 kg/m2 (28·6–29·8) in Polynesia and Micronesia; for women the range was from 21·8 kg/m2 (21·4–22·3) in south Asia to 32·2 kg/m2 (31·5–32·8) in Polynesia and Micronesia. Over these four decades, age-standardised global prevalence of underweight decreased from 13·8% (10·5–17·4) to 8·8% (7·4–10·3) in men and from 14·6% (11·6–17·9) to 9·7% (8·3–11·1) in women. South Asia had the highest prevalence of underweight in 2014, 23·4% (17·8–29·2) in men and 24·0% (18·9–29·3) in women. Age-standardised prevalence of obesity increased from 3·2% (2·4–4·1) in 1975 to 10·8% (9·7–12·0) in 2014 in men, and from 6·4% (5·1–7·8) to 14·9% (13·6–16·1) in women. 2·3% (2·0–2·7) of the world's men and 5·0% (4·4–5·6) of women were severely obese (ie, have BMI ≥35 kg/m2). Globally, prevalence of morbid obesity was 0·64% (0·46–0·86) in men and 1·6% (1·3–1·9) in women. Interpretation: If post-2000 trends continue, the probability of meeting the global obesity target is virtually zero. Rather, if these trends continue, by 2025, global obesity prevalence will reach 18% in men and surpass 21% in women; severe obesity will surpass 6% in men and 9% in women. Nonetheless, underweight remains prevalent in the world's poorest regions, especially in south Asia.