1. Global Change, Agriculture and Ecosystems Dennis Baldocchi Professor of Biometeorology Department of Environmental Science, Policy and Management College of Natural Resources CALDay 2007 April, 21

2. Outline Background Trends Processes –Warming Trends Extreme Events –Phenology –Dormancy –Elevated CO 2 –Water Use –Land Use

3. Climatic and Environmental Variables affecting Agricultural Production Temperature –Maximum, minimum, summed heat and cold units, phenology Water –Rainfall, amount, duration, frequency –Evaporation –Irrigation Sunlight CO 2 Pollution –ozone

4. Paleo- CO 2 and Temperature Record

5. Contemporary CO 2 Record

6. Temperature Anomaly Trends: Instrument Record

7. Blue Oak Range of CA Camp Pardee, CA

8. Mote et al. 2005 BAMS Trends for Climate between Nov and Mar

9. Temperature Length of Growing Season Length of Dormant Season Extreme cold –Fruit, flower, and/or pollination damage Extreme heat –Fruit damage –Leaf damage

10. Feng and Hu, 2004, J Theor Appl Clim Trends in Growing Season Length and Last Frost Dat United States

11. Feng and Hu, 2004, J Theor Appl Clim Trends, days per Decade

12. Estimating Winter Chill

13. Downward Trend in Chill Hours near Brentwood, East Contra Costa 20 year record, CIMIS Data

15. Projected Trends in Winter Chill

16. Almond Yield (ton acre -1 ) Almond Yield Anomaly D. Lobell, Unpublished, Data source: CIMIS, NASS Photo © David Sanger

17. Lobell et al 2006 AgForMet Critical Temperatures and Yield

18. Phenology

19. Apple blossom blooming in Germany

20. Menzel et al 2006 GCB; Menzel and Fabian, Nature, 1999 Regression Coefficient of Phenological Event with Time, days per year Phenology, a Measure of Global Change

21. Schwartz et al. 2006 GCB

22. Evaporation and Climate Change In Principle, Global Warming Should –Accelerate the Water Cycle –Increase Evaporation –Increase Cloud Cover –Increase Precipitation –Decrease Solar Radiation Negative feedback on evaporation

23. Projected Water Use in a Walnut Orchard

24. Liu et al. JGR 2004 Pan ET in China Literature is showing a long term trend with a decrease in pan evaporation Why, if Climate is Warming?

25. Explanations Pan Evaporation paradox (Brutsaert and Parlange, 1998) –Actual and Pan Evaporation exhibit complimentary behavior. –Observation of decreased pan evaporation indicates that actual evaporation is increasing in semi-arid regions Increase ET.. decreases VPD..decreases ETpan global reduction in pan ET reflects the dimming of radiation due to aerosols –Roderick and Farquhar –Liu et al

26. Global Solar Dimming Mishchenko et al. 2007 Science

27. Trends in Pan Evaporation in CA: Global Warming???Global Dimming??

28. Agriculture and Land use Change Albedo Bowen Ratio, H/LE partitioning –Leaf Area Index, Surface Wetness, Surface Resistance –Surface Temperature Carbon Uptake

29. Christy et al 2006 J Climate

30. Christy et al., 2006 J Climate

31. Long et al., 2006 Science CO2 and Crops

32. CO 2 and Photosynthesis Korner, 1996

34. Elevated CO 2, Facts and Myths Enhances Photosynthesis –Down-Regulation in Ps from Nutrient Limitations Reduces Stomatal Closure –Direct Effect Reduces Transpiration and Increases WUE –InDirect Effect and Positive Feedback Elevated Leaf Temperature, augments Transpiration Greater Growth and Leaf Area –Bigger plants grow faster. + –Bigger plants transpire more –Soil moisture pool depleted faster: - Herbivore Interactions –Insects eat more foliage to compensate for lower N quality of leaves

35. Feng and Hu, 2004, J Theor Appl Clim United States Trends in Dry and Wet Spells

36. Summary Climate Change is in Motion in California Long term production of valuable fruit crops is vulnerable due to trends in reduced winter chill –The future trends may not be linear, but could accelerate if winter fog patterns change Breeding programs are needed to produce cultivars that require less winter chill Water consumption will increase in the future

37. Solutions Irrigation scheduling and soil moisture management Mulches and increased soil organic matter to reduce soil evaporation and runoff Precision agriculture and drip irrigation Changes in crops, timing and rotation

38. We Link to Past, We have a Responsibility to the Future Palace of Minos at Knossos, ~2000 BC

40. Agriculture in the Climate System

44. Trends in Pan Evaporation: Global Warming??

45. Managed Agricultural Landscapes in California

46. McKinney et al, 2006 AgForMet

47. Beginning growing season R rye elogation Cherry blossom Apple blossom, Germany

48. Hildago et al 2005 J Hydromet

50. Lobell et al 2006 AgForMet