1. Attachai Jintrawet Multiple Cropping Center, Chiang Mai Univ., Chiang Mai. & Kim C. Nguyen, Atmospheric Res. Center, CSIRO. @ Sasin Graduate School of Management, Chulalongkorn University, Sasapatasala Building, room 521. Simulating impacts of future climate on rice and human in CNX, KKC Thailand

2. Rice production systems and climate changes Study methods Results Summary Issues

3. Global carbon cycle and stocks Thailand carries 1 million ha of riceland

4. Rice yield (kg ha -1 ) and population 0 2,500 5,000 Thailand: 65 Millions KK = 1.8 Millions CNX = 1.6 Millions 1974 84 94 00 OAE, 1975-2001

5. Historical weather data KK, CM 1985-99 Study tools KK using Roi Et soil CM using San Sai soil NSPT glutinous rice RD23 non-glutinous rice Predicted Regional GCM scenario weather data KK, CM 1985-1999 2006-2025 VS + CERES-Rice GFDL-MK3 climate model

6. Scenario 1: 1985-1999 Irrigation Irrigated RD23 NSPT MK3 WTH Rainfed RD23 NSPT MK3 WTH Rice variety Weather data Scenario 1 = 1xCO2 b/w 1985-1999 Using WTH & MK3 WTH Scenario 2 = 2xCO2 b/w 2006-2025 Using MK3 19851999 20062025 2035 2045 20552064 Urea Green manure WTH

7. Scenario 2: 2006-2025 Irrigation Irrigated RD23 NSPT MK3 Rainfed RD23 NSPT MK3 Rice variety Weather data Scenario 2 = 2xCO2 b/w 2006-2025 using MK3 19851999 20062025 2035 2045 20552064 Urea 0, 37.5, 75 kg ha -1 0.5, 2, 4 Mg ha -1 Total of 12 management rice production strategies

8. Scenario 1 between 1985- 1999 ProvincesWaterRice variety WTH MK3OAE KKC 2.200.891.67 RD 23. 2.631.001.67 NSPT 2.582.481.67 3.083.261.67 CNX NSPT 3.542.643.33 4.202.983.33 NSPT 4.033.983.33 4.775.163.33 Rainfed Irrigated RD 23 NSPT Rice yield (Mg ha -1 ) RMSE 1.001.03 RMSE 0.911.04

9. Rainfall between 1980-2030 0 500 1,000 1,500 2,000 2,500 ๒๕๒๓ 1980 ๒๕๓๓ 1990 ๒๕๔๓ 2000 ๒๕๕๓ 2010 ๒๕๖๓ 2020 ๒๕๗๓ 2030 CNX KKC

10. Scenario 2 b/w 2006-2024 Rainfed Irrigated 037.575037.575 NSPT 0.781.501.991.712.693.04 Rice yield at KKC (Mg ha -1 ) Rice varGM (kg ha -1 ) 6000 500 0.741.481.971.542.532.89 RD23 0.901.762.352.273.584.01 6000 500 0.841.732.331.963.313.76 Urea (kg ha -1 )

11. Scenario 2 b/w 2006-2024 Rainfed Irrigated 037.575037.575 NSPT 5.605.735.947.747.868.04 Rice yield at CNX (Mg ha -1 ) Rice varGM (kg ha -1 ) 6000 500 2.703.434.073.834.374.87 RD23 6.566.676.899.8810.0010.21 6000 500 3.204.245.091.965.786.43 Urea (kg ha -1 )

12. Impacts of the changes At CNX, simulated rice yields appeared to be higher than the current level. At KKC, simulated rice yields appeared to be lower than the current level. Flooding and soil erosion

13. Impacts of high rainfall Too much moisture in harvested products, use more energy to dry More leaching Less efficiency of chemical fertilizer

14. Summary It is possible to use a process-oriented rice model to simulate the production under various climatic, edaphic, and management conditions Slight impact on rice production during the next 20 years, except much higher rainfall volume in CNX areas. Need to develop warning systems.