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AGRICULTURE WATER DEMAND
Incorporating water in GCAM
Vaibhav Chaturvedi
Background
! Agriculture highest consumer of water globally, more than 70% of global water withdrawals
! Increasing population and food demand expected to put tremendous pressure on global water resources
! Additional water demand for energy crops
! Different challenges for different regions ! Present effort to analyze long term scenarios
related to global agricultural water consumption and withdrawal
2
Five Research Issues
1. How big will future global agricultural water consumption grow?
2. What is the effect of atmospheric CO2 concentration on agricultural water consumption through increasing plant water use efficiency?
3. What effect will emissions mitigation policy have on agricultural water consumption?
4. How big will future global IRRIGATION water consumption grow?
5. What will be the effect of increasing efficiency of water delivery in irrigation on water withdrawals?
3
Biophysical water
Irrigation water
4
Background: The Vocabulary of Agricultural Water
Total biophysical
water consumption
Green Water Water from
precipitation, directly used by crops or stored
as soil moisture
Blue Water Water withdrawn for irrigation from rivers,
lakes, aquifers or dams
Blue water demands on
irrigated lands
Green water demands on
rain-fed lands
Green water demands on
irrigated lands
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
Mt/y
r
Agricultural Production FiberCrop
PalmFruit
OtherGrain
OilCrop
Rice
Wheat
Corn
Root_Tuber
FodderHerb
FodderGrass
MiscCrop
SugarCrop
KEY Terms Calculating Water Consumption
Irrig
ated
R
ainf
ed
AgLU Model
6
1. How big will future agricultural water demands grow?
Biophysical Water Consumption by Crops
7
Total biophysical water consumption to almost double by 2050, after which the increase will be marginal Energy crops’ water consumption also increases, especially in the later half of the century
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
km3/
yr
Biophysical water consumption- CROPS
Biomass
FodderGrass
FodderHerb
PalmFruit
FiberCrop
SugarCrop
Root_Tuber
OtherGrain
Wheat
Rice
OilCrop
MiscCrop
Corn
Biophysical Water Consumption by Regions
8
Most of the water demand is in the developing nations of the world
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
km3/
yr
Biophysical water consumption- REGIONS
Korea
Japan
Eastern Europe
Canada
Australia_NZ
Middle East
Western Europe
Former Soviet Union
USA
China
Latin America
India
Southeast Asia
Africa
More than 70% of water for agriculture is consumed by developing regions, which increases to above 75% in 2095 70%
75%
16%
23%
Share of irrigation water
9
2. How Will Atmospheric CO2 Concentrations Affect Agricultural Water Demands?
! How will future increases in the atmospheric CO2 concentration from below 400 ppmv to above 750 ppmv affect biophysical water consumption?
! Increasing the atmospheric CO2 concentration ! Increases plant water use efficiency, other things being constant; ! Decreases water requirement for meeting evapo-transpiration
needs during crop growth stage
! We assume that a 1% increase in the atmospheric CO2 concentration decreases plant water consumption by 0.5%. [SOURCE: Leaky et al., 2009]
10
Effect of CO2 Concentration on Water Demands by Crops
AgLU Model
Exogenous crop yields; Fixed climate Current experiment only on water component
Effect of CO2 Concentra/on on Agricultural Water Demand
Global water consumption was reduced by 15% in 2050 and 30% in 2100 due to increasing water use efficiency by plants as a consequence of elevated atmospheric CO2 concentrations
11
IMPORTANT CAVEAT: The Impact of climate change on crop yields and water use are NOT included here. Future work.
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
km3/yr
Water demand with Constant Atmospheric CO2
Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095 km
3/yr
Water Demand with Increasing Atmospheric CO2 (772 ppm)
Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn
12
3. How Will Emissions Mitigation Policies Affect Agricultural Water Demands?
Water Consumption Under Climate Policy
! What could be the effect of a carbon price on land use change emissions on water consumption in agriculture?
! Carbon price can lead to changes in land use patterns
! We will explore the effect of a carbon price that limits radiative forcing to 4.5 W/m2 in the year 2100 on agricultural water consumption ! Note that we are not considering either the effect of climate
change or CO2 concentrations in this analysis
13
Effect of Emissions Mi/ga/on Depends on the Policy—Universal Carbon Tax
14
If all carbon is valued equally, then water demands actually decline slightly • The composition of crops changes—shift away from low carbon animal feed
crops to high carbon animal feed crops to feed livestock • Land shifts toward high carbon content use, mainly forests
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
km3/yr
Reference Scenario Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095 km
3/yr
Universal Carbon Tax Biomass
FodderGrass
FodderHerb
Palmfruit
FiberCrop
SugarCrop
Root_Tuber
OtherGrain
Wheat
Rice
OilCrop
MiscCrop
Corn
Effect of Emissions Mi/ga/on Depends on the Policy—Fossil Fuel ONLY Carbon Tax
15
If only FOSSIL FUEL carbon is valued, then agricultural water demands increase by more than 1/3 • Bioenergy demands for water increase dramatically after 2050 • Bioenergy demands for water alone are more than 40% of all agricultural
water demands by the century end
0
5000
10000
15000
20000
25000
2005 2020 2035 2050 2065 2080 2095
km3/yr
Universal Carbon Tax Biomass
FodderGrass
FodderHerb
Palmfruit
FiberCrop
SugarCrop
Root_Tuber
OtherGrain
Wheat
Rice
OilCrop
MiscCrop
Corn 0
5000
10000
15000
20000
25000
2005 2020 2035 2050 2065 2080 2095 km
3
Fossil Fuel Only Tax
Biomass
FodderGrass
FodderHerb
Palmfruit
FiberCrop
SugarCrop
Root_Tuber
OtherGrain
Wheat
Rice
OilCrop
MiscCrop
Corn
16
4. How much more irrigation would be required if current climate conditions persist?
Water for Irrigation ! How big will be the irrigation water consumption?
! Irrigation critically important for increasing cropping intensity and productivity
! Agricultural irrigation water consumption depends on the extent of area under irrigation and production from irrigated areas
17
200
250
300
350
400
450
500
550
600
2000
2500
3000
3500
4000
4500
5000
5500
6000
2005 2030 2050
Prod
uctio
n in
mill
ion
tons
Increase in irrigated area and production
Production Area
Irrig
ated
are
a in
mill
ion
hect
are
Assumption: FAO projections of
irrigated area and production
Total Irriga/on Water Consump/on
18
0
500
1000
1500
2000
2500
3000
3500
2005 2020 2035 2050 2065 2080 2095
km3/yr
Blue water consump/on
Korea
Japan
Canada
Australia_NZ
Western Europe
Eastern Europe
Former Soviet Union
USA
Middle East
China
LaSn America
Africa
Southeast Asia
India
200% increase in irrigation water consumption, which can be expected to increase to more than 3000 km3/yr in 2095 compared to less than 1000 km3/yr in 2005 As a share of global biophysical water consumption, irrigation water increases from 15% in 2005 to 23% in 2095 Highest increase to be observed in India followed by Southeast Asia
19
5. How large can be the effect of increase in irriga/on water delivery efficiency?
Global Water Withdrawal in 2005
Consumption 1007 km3
(40%) Efficiency Losses 1506 km3 (60%)
Total 2513 km3
Irrigation Water Delivery Efficiency
! What is the effect of increase in irrigation water delivery efficiency on water withdrawals?
! Difference between water withdrawal for irrigation and blue water consumption due to efficiency losses
! Significant variation in water delivery efficiency across regions
! Increase in efficiency could potentially save substantial water
! Assumption: Constant biophysical water and water for irrigation, but water delivery efficiency increasing at .5%/annum up to maximum of 70%
20
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
2005 2020 2035 2050 2065 2080 2095
km3/
yr
Increasing Efficiency Korea
Japan
Former Soviet Union
Eastern Europe
Canada
Australia_NZ
Western Europe
USA
China
Middle East
Africa
Latin America
Southeast Asia
India
Irrigation Water Delivery Efficiency
21
Global irrigation water withdrawals can be reduced by 20% in 2050 and 32% in 2095 through improving irrigation delivery efficiency
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
2005 2020 2035 2050 2065 2080 2095
km3/
yr
Constant Efficiency Korea
Japan
Former Soviet Union
Eastern Europe
Canada
Australia_NZ
Western Europe
USA
China
Middle East
Africa
Latin America
Southeast Asia
India
Key Learning
! Total biophysical water consumption to almost double by 2050, after which the increase will be marginal
! CO2 concentration could significantly affect global water consumption by increasing plant water use efficiency
! Emission mitigation policy excluding land use change emissions can result in high water consumption by bio-energy crops
! Future demand for irrigation water can put severe pressure on irrigation water resources
! Irrigation delivery efficiency improvement could yield substantial savings in water withdrawals
22
Future Research
! Including water pricing for irrigation water and clearing agricultural water markets
! Introducing end use water consumption technologies in agriculture
! Endogenous water use technology selection on the basis of price and income within AgLU
! Linking water input to crop productivity
! Modeling irrigated and rain-fed land separately within AgLU model
23
ENERGY WATER DEMAND Next…
25
Backup Slides
Green water demands on
rain-fed lands
Blue water demands on
irrigated lands
Green water demands on
irrigated lands
Ag Production
1 Total
biophysical water
consumption
2 Water consumption on irrigated
areas (G+B)
Ag Area
3 Green Water consumption on irrigated
areas
4 Blue water consumption
5 Water withdrawal
Irrigation Delivery Efficiency
Calculating water consumption in agriculture
Share of irrigated area/
production
26
Ag Area
Calculating water for irrigation
Water consumption on irrigated
areas (Green+Blue)
Share/Increase in irrigated production
FAO projection based
assumptions
27
Green water consumption on irrigated
areas
Share/Increase in irrigated area
FAO projection based assumptions
Blue water consumption
0
2000
4000
6000
8000
10000
12000
14000
16000
2005 2020 2035 2050 2065 2080 2095
km3/
yr
Biophysical water consumption
Korea
Japan
Eastern Europe
Canada
Australia_NZ
Middle East
Western Europe
Former Soviet Union
USA
China
Latin America
India
Southeast Asia
Africa
Green water fixed/unit irrigated
area
Water for Irriga/on
28
Source: www.iwmigmia.org
Some Key Terms and Rela/onships
29
Biophysical water
Green water Blue water
Green water- to Rainfed
Crops
Green water- to Irrigated
Crops
Green water will be used on both dry land crops and irrigated crops.
What variables are we interested in?
! Biophysical water consumption ! Derived from our virtual water content and crop
production.
! Blue water consumption ! Blue water withdrawal
30