The Chinese Academy of Agricultural Sciences (CAAS) and the International Food Policy Research Institute (IFPRI) jointly hosted the International Conference on Climate Change and Food Security (ICCCFS) November 6-8, 2011 in Beijing, China. This conference provided a forum for leading international scientists and young researchers to present their latest research findings, exchange their research ideas, and share their experiences in the field of climate change and food security. The event included technical sessions, poster sessions, and social events. The conference results and recommendations were presented at the global climate talks in Durban, South Africa during an official side event on December 1.

1. ICCCFS
2011
Global Irrigation Requirement
under the scenario of SRA1B
Zhentaoi Cong1o, Jun Liul1, Tingju Zhu2 r
E d t y u r s o g a n h e e
1 Department of Hydraulic Engineering, Tsinghua University, China
2 International Food Policy Research Institute

2. Background
Irrigation is by far the largest single user of water globally,
accounting for approximately 70% of global water withdrawal and
90% of global consumptive water use (FAO, 2011)
Irrigated land accounts for no more than 20% of the world's
cultivated land, but contributes about 40% of all agricultural
production and 60% of cereal production (FAO, 2011).
Assessing irrigation water requirement under climate change is
essential for understanding potential future water crisis and food
security.
Given the potential impacts of climate change on irrigation water
uses, estimating climate change impacts on irrigation water
requirements is a critical step towards evaluating how much
water will be needed for irrigation in the future (Döll, 2002).

3. Framework
IPCC Scenarios + GCMs Rn, T, RH, u (monthly)
FAO-Penman-Monteith
ET0 – Reference Evapotranspiration
SAGE FAO-Kc
Crop water requirement
ETc = Kc*ET0
Pe – Effective Precipitation
Net Irrigation Requirement
IR = ETc－Pe

4. IPCC Scenarios and GCMs
Scenarios
1PTO2X CO2 concentration increase 1% /year, until DOUBLE; constant thereafter.
1PTO4X CO2 concentration increase 1%/year, until QUADRUPLE; constant thereafter.
20C3M Greenhouse gasses increasing as observed through the 20th century.
COMMIT Atmospheric burdens of long‐lived greenhouse gasses are held fixed at AD2000 levels.
PICTL Constant pre‐industrial levels of greenhouse gasses.
Rapid economic growth; Population peaks in mid‐century and declines thereafter; New
SRA1B
and more efficient technologies; Balanced energy sources.
Heterogeneous world: Continuously increasing population; Regionally oriented
SRA2
economic growth(more fragmented and slower).
Convergent world: Same population as SRA1B; Rapid changes in economic
SRB1 structures(towards service and information); Reductions in material intensity; Clean and
resource‐efficient technologies.
Baseline: 20C3M scenario, 1961-1990
Climate change scenario: SRA1B scenario, 2046-2065

5. IPCC Scenarios and GCMs
Scenarios
Source: Figure 10.4 in Meehl, et al. (2007)

6. IPCC Scenarios and GCMs
GCMs
BCC‐CM1 ECHAM5/MPI‐OM
1.125°×1.125°
BCCR BCM2 MRI‐CGCM2.3.2
4°×3°
CGCM3_1‐T47 AOM 4x3 NASA, USA
CGCM3_1‐T63 GISS ModelE‐H
CNRM‐CM3 GISS ModelE‐R
ECHO‐G CCSM3
CSIRO Mark 3.0 PCM
CM2.0 ‐ AOGCM MIROC3.2‐HI 1.125°×1.125°
Japan
4°×5° INMCM3.0 MIROC3.2‐MED
INM 2.8125°×2.8125°
IPSL‐CM4 HadCM3 Japan
FGOALS1.0_g HadGEM1

7. Method to calculate ET0
FAO Penman-Monteith equation
Where:
– ET0 : reference evapotranspiration [mm day-1]
– T : mean daily air temperature [°C]
– Rn : net radiation [MJ m-2 day-1]
– G : soil heat flux density [MJ m-2 day-1]
– es : saturation vapor pressure [kPa]
– ea : actual vapor pressure [kPa]
– Δ : slope of temperature-pressure curve [kPa °C-1]
– γ : psychrometric constant [kPa °C-1]
– u: wind speed [m/s]

8. Change of ET0
5 GCMs MIROC3_2-HI
BCM2 INMCM3
AOM MIROC3_2-MED

9. What caused the increasing of ET0 ?
R
RH
The change of ET0 is similar to
T
the air temperature in the future.
U

10. Land use
SAGE
the Center for Sustainability And the Global Environment
University of Wisconsin-Madison
Global Land Use Database, 1992, 18 crops, 0.5°× 0.5°
Wheat Maize
Rice Cotton

11. Köppen climate classification
Kc in FAO

12. Kc in FAO

13. Crop water requirement
Change of ETc of all crop in 5 GCMs Change of ETc of maize in 5 GCMs
Change of ETc of rice in 5 GCMs Change of ETc of wheat in 5 GCMs

14. Change of ETc
Region MIROC3_2‐HI BCM2 INMCM3 AOM MIROC3_2‐MED
China +4.9% +2.6% +7.8% +4.7% +5.4%
USA +12.6% +8.8% +13.6% +4.9% +14.7%
India +4.4% +1.9% +1.2% +1.6% ‐3.2%
Australia +12.4% +6.5% +8.9% +6.8% +5.4%
Europe +10.9% +6.7% +8.8% +3.7% +17.9%
Russia +8.5% +4.6% +9.7% +0.5% +8.7%
Global +8.6% +5.2% +7.7% +4.4% +7.5%

15. Change of P
5 GCMs MIROC3_2-HI
BCM2 INMCM3
AOM MIROC3_2-MED

16. Change of P
Region MIROC3_2‐HI BCM2 INMCM3 AOM MIROC3_2‐MED
China +12.1% +5.0% +4.3% +1.8% +6.6%
USA ‐2.5% ‐2.2% ‐5.0% +5.8% ‐11.3%
India +3.7% +9.4% +13.0% +11.4% +14.5%
Australia ‐2.0% +4.1% ‐7.1% ‐9.9% +7.6%
Europe +5.8% ‐0.8% ‐0.7% +0.5% +4.4%
Russia +13.0% +4.4% +8.4% +8.1% +10.5%
Global +3.1% +1.6% +1.8% +3.7% +3.0%

17. Precipitation vs ETc
Effective rainfall (USDA)
Time step: 10 days
Random Matching with the ETc

18. Change of Irrigation Requirement (IR)
5 GCMs MIROC3_2-HI
BCM2 INMCM3
AOM MIROC3_2-MED

19. Change of Irrigation Requirement (IR)
Region MIROC3_2‐HI BCM2 INMCM3 AOM MIROC3_2‐MED
China +3.7% +0.6% +10.1% +1.4% +5.7%
USA +30.6% +23.4% +27.9% +6.4% +33.6%
India +12.8% ‐1.1% ‐5.7% ‐1.6% ‐10.5%
Australia +15.0% +3.5% +8.3% +7.8% +1.9%
Europe +11.2% +17.1% +22.0% +13.9% +31.3%
Russia +6.2% +12.9% +22.7% +3.8% +5.8%
Global +14.8% +8.5% +11.6% +5.0% +12.1%

20. IR‐Irrigation Requirement
ETc China:
ETc - increasing
P - inceasing
IR - not obviously
P
USA, Mediterranean area
ETc - increasing
P - deceasing
IR - increasing obviously
IR

21. Change of Irrigation Requirement (IR)
Doll, 2002, Figure1(C), 2020, ECHAM4

22. Change of Irrigation Requirement (IR)
Food production of countries, FAO
Wheat
Rice
It is a big challenge for future world food security.
Maize

23. Change of IR in China
5 GCMs MIROC3_2-HI
BCM2 INMCM3
AOM MIROC3_2-MED

24. IR‐Irrigation Requirement
Change of IR in SRA1B 2046-2065 with MIROC3.2_HI

25. Conclusions
Trends of ET0, ETc, P and IR under climate changes depend
on different GCMs and different regions.
ET0 and ETc would increase all over the world due to global
warming.
IR would significantly increase in the Mediterranean area and
in USA due to the increase in ET0 and the decrease in P.

26. Outlook
More GCMs and RCM;
Coupling the crop growth model and hydrological model to
predict the irrigation requirement under climate changes;
To consider the trend of precipitation frequency.

27. ICCCFS
2011
E d i t y o u r s l o g a n h e r e
congzht@tsinghua.edu.cn