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.
Virtual water: Missing piece in water-food security puzzle
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
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
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
“ The green revolution has won a temporary success in man’s war against hunger and deprivation; it has given man a breathing space.
Physiological level: increase transpiration, CO2 effectiveness and harvest index
Three ways to shift the curve from G3 towards G4: CO2 concentrating mechanisms, increased mesophyll conductance to CO2, increased Rubisco specificity factor.