This document discusses food security and water scarcity challenges. It presents virtual water as a missing piece in ensuring food security. Virtual water refers to the volume of water used to produce food that is traded internationally. Major points: - Water scarcity and increasing food demands pose challenges for global food security. Agricultural water use is projected to increase significantly by 2050. - Options to improve food security through increasing water productivity and efficiency as well as breeding drought-tolerant crops are important but have limitations. - International food trade, or virtual water flows, can help offset localized water scarcity and food insecurity. Countries can import food from water-abundant regions to meet demands.

1. virtual water: a missing piece in the water-food
security puzzle?
David YAWSON
d.o.yawson@dundee.ac.uk

2. outline:::
food security: a wicked problem?
water for food security: a challenge
options for food security
virtual water: the missing piece
concluding remarks

3. food security pressures – wicked problem?
scarce water for all
Bio-engines
a warmer world
Our daily BREAD
affluence
9 billion mouths
peak phosphorus peak oil

4. water for food security: a challenge

5. water for food security: a challenge
Source: World Water Council
why is useless
diamond more
expensive than
ESSENTIAL water?
[Aristotle]
“Water is the next petroleum” – Goldman Sachs
(Sunday Times, June 8, 2008)

6. water for food security: a challenge
Source: World Water Council

7. water for food security: a challenge
Finite
water
resources Domestic, urban
and industrial
Ecosystem services
(environmental flows)
Food
production

8. water for food security: a challenge
• Agriculture (70% global water use)
(Rockstrom, 2003)
2000:
6,800 km3
yr-1
2050:
12,600 km3
yr-1

9. maintaining food security under
water scarcity
some options
managing ‘the limits to growth’

10. Green revolution? in water-scarce
regions?
Norman Borlaug (1914-
2009)
Green Revolution

11. food security options
water productivity,
efficiency & breeding
water productivity,
efficiency & breeding
Water
supply
Water
supply
Food
demand
options:
1. Agronomy:
•Improve water productivity
-minimize unproductive water losses
-maximize water retention in root zone
-sustainable intensification???
options:
2. Physiology & Breeding:
-water productivity (physiological level)
-drought tolerance (genetic level)
•Social:
-reducing food waste
-dietary shifts

12. Source: Parry et al. (2005)
NB: Selection for
physiological WUE is
counterproductive
food security options

13. virtual water: the missing piece
water productivity,
efficiency & breeding
water productivity,
efficiency & breeding
Water
supply
Water
supply
Food
demand
virtual water
(food trade)
virtual water
(food trade)
Virtual water is the volume of
water consumptively used to
produce a unit crop that is traded

14. • water scarcity & food insecurity are
localized
• agriculture has low return on
investment
• food insecurity  upheavals
• the entire food system is a business
virtual water: the missing piece

15. Net virtual water flows (>2 Gm3
yr-1
) associated with wheat
trade (1996-2005). Source: Mekonnen and Hoekstra (2010).
virtual water: the missing piece

16. Global crop consumptive blue and green water use (km3
yr-1
)
Source: Hoff et al. (2010).
Blue water
(irrigation)
Green water1
Green water2
Green water3
GCWM 1180-1448* 4586-4772* 5505-5731* 9823(PM)
GEPIC 927 - 4987 6371
H08 1530 4700 5550 9540
IMPACT 1425 3272 4975 -
LPJmL 1364 5088 5469 -
waterGap 1300 - - 8290
WBM 1301 - - 9406
* For different PET calculations
PM
PET calculated by Penman-Monteith equation
1
rain-fed cropland, cropping period
2
rain-fed and irrigated cropland, cropping period
3
rain-fed and irrigated cropland, full year
virtual water: the missing piece

17. summary & concluding remarks
• future food security is a ‘wicked problem’
• a wicked problem has one solution: suite of
solutions
• water scarcity: slowable, inevitable, irreversible
• known options for food security worth pursuing
• BUT virtual water (food trade) is a missing piece in
the suite of solutions to the water-food security
puzzle
• virtual water:
- a soft-path approach to offset effect of water
scarcity on food security
-opportunity for rethinking sustainable investment in
agriculture and agro-environmental governance
-potentially effective & efficient path to food security
-needs to be promoted to the water-food security
policy arena

18. take home message
“…famine can be caused not only by insufficient food
production but also by socioeconomic dynamics and
failure of public action” [Amartya Sen].
virtual water can help avert future catastrophe!

19. supervisors
1. Dr Tom Ball (Geography, Univ. of Dundee)
2. Dr Barry Mulholland (ADAS UK Ltd)
3. Prof. Philip White (James Hutton Institute)
4. Dr Sushil Mohan (Economic Studies, Univ. of
Dundee)

20. for low virtual water content