Targets for a sustainable water footprint

Arjen Hoekstra

www.ayhoekstra.nl

Aral Sea Basin, Central Asia1989 2008

Water allocationhow much can we use?

Strawberries for export

California, USA

Top-6 water consumers California

1. animal feed

2. almonds & walnuts

3. residential areas

4. rice

5. grapes

6. cotton

Water allocationto which purposes?

what are reasonable amounts?

Car driving on bio-ethanol

from sugarcane:

40-500 litre/km

Water allocationwho finally benefits?

Many countries have externalized

their water footprint to other countries

Water allocationGlobal dependences

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

Economic

efficiency

Keep WF of products to

reasonable levels

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

Economic

efficiency

Keep WF of products to

reasonable levels

Social equity Keep WF of communities to

reasonable levels

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

Economic

efficiency

Keep WF of products to

reasonable levels

Social equity Keep WF of communities to

reasonable levels

Political

security

Reduce risks related to water

use in supply chains

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target Means

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

WF caps by river basin (based on

available runoff, environmental water needs

& waste assimilation capacity)

Economic

efficiency

Keep WF of products to

reasonable levels

Social equity Keep WF of communities to

reasonable levels

Political

security

Reduce risks related to water

use in supply chains

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target Means

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

WF caps by river basin (based on

available runoff, environmental water needs

& waste assimilation capacity)

Economic

efficiency

Keep WF of products to

reasonable levels

WF benchmarks by product (based on

best available technology)

Social equity Keep WF of communities to

reasonable levels

Political

security

Reduce risks related to water

use in supply chains

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target Means

Environmental

sustainability

Reduce WF within catchments

to maximum sustainable levels

WF caps by river basin (based on

available runoff, environmental water needs

& waste assimilation capacity)

Economic

efficiency

Reduce WF of products to

reasonable levels

WF benchmarks by product (based on

best available technology)

Social equity Reduce WF of communities to

reasonable levels

Fair WF shares by nation

Political

security

Reduce risks related to water

use in supply chains

Targets to reduce humanity’s water footprint to sustainable levels

Source: Hoekstra and Wiedmann (2014) Humanity’s unsustainable environmental footprint, Science

Target Means

Environmental

sustainability

Keep WF in catchments to

maximum sustainable levels

WF caps by river basin (based on

available runoff, environmental water needs

& waste assimilation capacity)

Economic

efficiency

Keep WF of products to

reasonable levels

WF benchmarks by product (based on

best available technology)

Social equity Keep WF of communities to

reasonable levels

Fair WF shares by nation

Political

security

Reduce risks related to water

use in supply chains

Max. degree of import dependency

(external / total WF) per region

Source: Mekonnen & Hoekstra (2015)

The water footprint of humanity: not sustainable

Blue water scarcity = blue WF / maximum sustainable blue WF

Blue water footprint reduction targets

Guadiana basin (Spain)

Environmental

flow requirement

The blue WF exceeds the max. sustainable blue WF

from May to November.

Blue WF reduction

target

Maximum sustainable

blue WF

Water pollution level per river basin

Water pollution level = grey WF / maximum sustainable grey WF

Nitrogen

Source: Liu, Kroeze, Hoekstra and Gerbens-Leenes (2012)

Source: Mekonnen & Hoekstra (2014)

The water footprint of humanity: not efficient

Spatial differences in the consumptive water footprint of barley

Worldwide reduction of consumptive water footprints of crops to benchmark levels set by the best 25% of global

production, would result in a global water saving of 40%.

Source: Mekonnen & Hoekstra (2014)

The water footprint of humanity: not efficient

Differences in the green-blue water footprint of barley

Worldwide reduction of water footprints of barley to benchmark level set by the best 25%

of global production, would result in a global water saving of 60%.

546

25

Global average water footprint

The water footprint of humanity: not fairly distributed

Source: Hoekstra & Mekonnen (2012) The Water Footprint of Humanity, PNAS

40% of the water footprint of European consumers is outside Europe

soybean

coffee

soybeanwheat

cotton

cotton,industrialproducts

wheat, sunflower seed, cotton, industrial products

soybean,

sunflower seed

cotton

coffee

cocoa

cotton

Source: Hoekstra & Mekonnen (2012) The Water Footprint of Humanity, PNAS

The water footprint of humanity: large inter-regional dependencies

soybean

coffee

soybeanwheat

cotton

soybean,

sunflower seed

cocoa

Global blue water footprint of UK consumption

41% of UK's global blue WF is

unsustainable (located in places where

blue WF > max. sustainable blue WF)

51% of the unsustainable part of UK's

blue WF is located in six countries:

1. Spain (15%)

2. USA (11%)

3. Pakistan (8%)

4. India (7%)

5. South Africa (6%)

6. Iran (5%)

dates

apples

grapes

sugarcane

rice

rice, tea

sugarcane

rice, olives,

grapesrice,grapes

Source: Hoekstra & Mekonnen (2015)

The need for contraction and convergence

Source: Hoekstra (2014) Wise freshwater allocation, UNESCO-IHE

0

500

1000

1500

2000

2500

3000

2000 2020 2040 2060 2080 2100

Water footprint per capita (m3/yr/cap)

USA

China

Maximum sustainable water footprint

Time

Business as Usual

Business as Usual

Further reading

►Water footprint caps by river basin

►Water footprint benchmarks by product

► Fair water footprint shares by nation

►Water security by region

www.ayhoekstra.nl