AGRICULTURE WATER DEMAND. Incorporating water in GCAM. Vaibhav Chaturvedi

Transcription

1 AGRICULTURE WATER DEMAND Incorporating water in GCAM Vaibhav Chaturvedi

2 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

3 Five Research Issues Biophysical water 1. How big will future global agricultural water consumption grow? 2. What is the effect of atmospheric CO 2 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 Irrigation water

4 Background: The Vocabulary of Agricultural Water 4

5 KEY Terms Green Water Water from precipitation, directly used by crops or stored as soil moisture Blue Water Water withdrawn for irrigation from rivers, lakes, aquifers or dams Calculating Water Consumption Irrigated Rainfed Green water demands on rain-fed lands Green water demands on irrigated lands Blue water demands on irrigated lands Mt/yr AgLU Model Agricultural Production Total biophysical water consumption FiberCrop PalmFruit OtherGrain OilCrop Rice Wheat Corn Root_Tuber FodderHerb FodderGrass MiscCrop SugarCrop

6 1. How big will future agricultural water demands grow? 6

7 Biophysical Water Consumption by Crops km3/yr Biophysical water consumption- CROPS Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn 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

8 Biophysical Water Consumption by Regions km3/yr Biophysical water consumption- REGIONS % 70% 75% % Korea Japan Eastern Europe Canada Australia_NZ Middle East Western Europe Former Soviet Union USA China Latin America India Southeast Asia Africa Most of the water demand is in the developing nations of the world More than 70% of water for agriculture is consumed by developing regions, which increases to above 75% in Share of irrigation water

9 2. How Will Atmospheric CO 2 Concentrations Affect Agricultural Water Demands? 9

10 Effect of CO 2 Concentration on Water Demands by Crops! How will future increases in the atmospheric CO 2 concentration from below 400 ppmv to above 750 ppmv affect biophysical water consumption?! Increasing the atmospheric CO 2 concentration! Increases plant water use efficiency, other things being constant;! Decreases water requirement for meeting evapo-transpiration needs during crop growth stage AgLU Model Exogenous crop yields; Fixed climate Current experiment only on water component! We assume that a 1% increase in the atmospheric CO 2 concentration decreases plant water consumption by 0.5%. [SOURCE: Leaky et al., 2009] 10

11 Effect of CO 2 Concentra/on on Agricultural Water Demand km3/yr Water demand with Constant Atmospheric CO Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn km3/yr Water Demand with Increasing Atmospheric CO 2 (772 ppm) Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn 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 CO 2 concentrations IMPORTANT CAVEAT: The Impact of climate change on crop yields and water use are NOT included here. Future work. 11

12 3. How Will Emissions Mitigation Policies Affect Agricultural Water Demands? 12

13 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/m 2 in the year 2100 on agricultural water consumption! Note that we are not considering either the effect of climate change or CO 2 concentrations in this analysis 13

14 Effect of Emissions Mi/ga/on Depends on the Policy Universal Carbon Tax km3/yr Reference Scenario Biomass FodderGrass FodderHerb PalmFruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn km3/yr Universal Carbon Tax Biomass FodderGrass FodderHerb Palmfruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn 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 14

15 Effect of Emissions Mi/ga/on Depends on the Policy Fossil Fuel ONLY Carbon Tax km3/yr Universal Carbon Tax Fossil Fuel Only Tax Biomass FodderGrass FodderHerb Palmfruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat Rice OilCrop MiscCrop Corn km Biomass FodderGrass FodderHerb Palmfruit FiberCrop SugarCrop Root_Tuber OtherGrain Wheat 5000 Rice OilCrop MiscCrop 0 Corn 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 15

16 4. How much more irrigation would be required if current climate conditions persist? 16

17 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 Increase in irrigated area and production 17 Production in million tons Production Area Irrigated area in million hectare Assumption: FAO projections of irrigated area and production

18 Total Irriga/on Water Consump/on 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 18

19 5. How large can be the effect of increase in irriga/on water delivery efficiency? Global Water Withdrawal in 2005 Consumption 1007 km 3 Efficiency Losses (40%) 1506 km 3 (60%) Total 2513 km 3 19

20 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

21 Irrigation Water Delivery Efficiency km3/yr Constant Efficiency 9000 Korea 8000 Japan Former Soviet Union 7000 Eastern Europe 6000 Canada Australia_NZ 5000 Western Europe USA 4000 China 3000 Middle East Africa 2000 Latin America 1000 Southeast Asia India 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 Global irrigation water withdrawals can be reduced by 20% in 2050 and 32% in 2095 through improving irrigation delivery efficiency 21

22 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 bioenergy 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

23 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

24 Next ENERGY WATER DEMAND

25 Backup Slides 25

26 Calculating water consumption in agriculture 2 Water consumption on irrigated areas (G+B) Share of irrigated area/ production 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 4 Blue water consumption Irrigation Delivery Efficiency 5 Water withdrawal 3 Green Water consumption on irrigated areas Ag Area 2 6

27 Calculating water for irrigation km3/yr Biophysical water consumption Korea Japan Eastern Europe Canada Australia_NZ Middle East Western Europe Former Soviet Union USA China Latin America 0 India Southeast Asia Africa Share/Increase in irrigated production FAO projection based assumptions Water consumption on irrigated areas (Green+Blue) Blue water consumption Ag Area Green water fixed/unit irrigated area Share/Increase in irrigated area FAO projection based assumptions Green water consumption on irrigated areas 2 7

28 Water for Irriga/on Source: 28

29 Some Key Terms and Rela/onships Biophysical water Green water Blue water Green waterto Rainfed Crops Green waterto Irrigated Crops Green water will be used on both dry land crops and irrigated crops. 29

30 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