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Reducing humanity's water footprintChallenges from a global perspective
Arjen Y. Hoekstra | www.ayhoekstra.nl
WEF’s Global Risk Report 2016
Sustainability of water useWater use efficiencyFair sharing of waterResource security
New Delhi, 4 Oct 2006
The Coca Cola Company
Water footprint of a 0.5 litre PET-bottle cokeas produced in the Netherlands
0.44 litre water content27.6 litre for sugar5.3 litre for PET bottle and closure3.0 litre for other ingredients & overheads___________________36 litre total
Water footprint of a Coke
Cereals27%
Starchyroots2%
Sugar1%
Pulses 0.4%
Nuts0.3%
Oilcrops 2%
VegetableOils 3%Vegetables
8%Fruits6%
Coffee, tea,cocoa1%
Wine&beer0.4%
Fibres3%
Tobacco1%
Rubber1%
Meat26%
Offals 1%
AnimalFats 1%
Milk 2% Eggs
5%
Hides&skins2%
Industrialproducts4%
Domesticwatersupply4%
The water footprint of the Chinese consumer
Source: Mekonnen & Hoekstra (2011)National Water Footprint Accounts.
3000 litre/day
soybean
wheat
barley
The water footprint of the Chinese consumer
alfalfa
Strawberries for export
Animal feed from California
Top-6 water consumers California:1. animal feed (e.g. alfalfa)2. almonds & walnuts3. residential areas
Blue water footprintvolume of surface or groundwater consumed (evaporated)= net water abstraction
The water footprint of a product
Source: Hoekstra et al. (2011) The Water Footprint Assessment Manual, Earthscan, London, UK
Grey water footprintvolume of surface or groundwater polluted
Green water footprintvolume of rainwater consumed (evaporated)
Precipitationin a catchment
Environmentalwater needs
Evapotranspiration(green water)
Maximum sustainablegreen WF
Maximumsustainable
blue WF
Environmental water needs
Green wateravailability
Blue wateravailability
Runoff(blue water)
The maximum sustainable green and blue water footprint
Grey water footprintThe volume of water required to assimilate pollutants
Source: Hoekstra et al. (2011) The Water Footprint Assessment Manual, Earthscan, London, UK
Grey water footprint = (Load / Critical load) ´ River flow
Max. sustainable grey water footprint = River flow
Source: Mekonnen & Hoekstra (2016)
The blue water footprint of humanity: not sustainable
We need to agree on water footprint caps per river basin (specified per month)
Blue water scarcity = blue WF / maximum sustainable blue WF
Water pollution level = grey WF / maximum sustainable grey WF
Source: Mekonnen & Hoekstra (2017)
The grey water footprint of humanity: not sustainable
Phosphorus
The water footprint of humanity: not efficient
Spatial differences in the water footprint of wheat
Reduction of water footprints of crops to benchmark levels set by the best 25% of global production,will result in a global water saving of 40%.
Source: Mekonnen & Hoekstra (2014)
litre/kcal
starchy roots 0.5
cereals 0.5
sugar crops 0.7
pulses 1.1
vegetables 1.3
fruits 2.1
pork 2.2
poultry 3.0
beef 10.2
Global average water footprint
The water efficiency of our food
Source: Mekonnen & Hoekstra (2012) A global assessment of the water footprint of farm animal products, Ecosystems
► The WF of animal production is 29% of the WF of the agricultural sector.
► The WF of the agricultural sector is 92% of the total WF of humanity.
Source: Mekonnen & Hoekstra (2012) A global assessment of the water footprint of farm animal products, Ecosystems
The water efficiency of our food
Source: Vanham et al. (2017) Journal of HydrologySpecial Issue on Water in megacities: new risks, new solutions
The water efficiency of our food – example Hong Kong
Diet scenarios:
REF Reference period (1996-2005)
HEALTHY Healthy diet, based on Chinese dietary guideline
PESCO-VEG Pesco-vegetarian diet
VEG Vegetarian diet
Water footprint
The water footprint of our choices
Stop showering = water saving of 50 litre/day Stop eating meat = water saving of 800 litre/day
The two separate worlds of water and energy
► The water sector is becoming more energy-intensive
- desalination- pumping deeper groundwater- large-scale (inter-basin) water transfers
► The energy sector is becoming more water-intensive
- shale oil & gas (fracking)- tar sands & oil / kerogen shales- biomass
Source: Hoekstra (2013) The Water Footprint of Modern Consumer Society, Routledge, London, UK
0"
2000"
4000"
6000"
8000"
10000"
12000"
14000"
16000"
18000"
20000"
Sugar"b
eet"
Sugar"cane"
Potatoes"
Cassava"
Maize"
Barle
y"
Rye"
Rice"
Whe
at"
Sorghu
m"
Oil"palm
"
Rape
seed
"
Grou
ndnu
ts"
Soybeans"
Sunfl
ower""
Seed
"coG
on"
Grey"
Blue"
Green"
Water"fo
otprint"(litre"of"w
ater"per"litre"of"biofuel)" BioKethanol" Biodiesel"
Source: Mekonnen & Hoekstra (2011)
The water efficiency of energy supply
WF of biofuels are about 100-1000x larger than WF of fossil
fuels
The water efficiency of electricity
Source: Mekonnen, Gerbens-Leenes & Hoekstra (2015)
?
?
The water footprint of electricity in 2035 – IEA scenarios
Source: Mekonnen, Gerbens-Leenes & Hoekstra (2016)
0
5
10
15
20
25
0
200
400
600
800
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1400
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Reference (2010) Current policiesscenario
New policiesscenario
450 scenario Efficient worldscenario
Adapted 450scenario
CO
2em
issi
ons
(bill
ion
tonn
e/y)
Con
sum
ptiv
e W
F re
late
d to
ele
ctric
ity a
nd h
eat p
rodu
ctio
n (b
illio
n m
3 /y)
Hydropower Firewood Coal and lignite Nuclear Natural gasOil Geothermal Solar Wind CO2 emissions
Carbonfootprint
Waterfootprint
Global average water footprint
The water footprint of humanity: not fairly distributed
Source: Hoekstra & Mekonnen (2012) The Water Footprint of Humanity, PNAS
Arrows show gross virtual water flows >15 Gm3/yr
Source: Hoekstra & Mekonnen (2012) The Water Footprint of Humanity, PNAS
On average, 26% of the water footprint of national consumption lies outside the country
The water footprint of humanity: international dependencies
52Gm3/y
Source: Hoekstra & Chapagain (2008)
Virtual water transfers in China
Sources: Zhuo et al. (2016)
Virtual water transfers in China
Future under growth and climate change
Water scarcity
Net virtualwater export
Net virtualwater import
China
Northern EuropeJapan
IndiaSouthAmerica
Middle EastNorth & South Africa
MexicoSouthern Europe
USAAustralia
Source: Hoekstra (2012)
CentralAfrica
► water footprint caps by river basin
► water footprint benchmarks by product
► best available technology and practice► water disclosure► product transparency
► fair water footprint shares by consumer
► national water footprint reduction targets
► greater levels of (water-food-energy) self-sufficiency
Wise water governance
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The need for contraction and convergence
Source: Hoekstra (2014) Wise freshwater allocation, UNESCO-IHE
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Thanks
Web www.ayhoekstra.nlTwitter @AYHoekstra
