1. Climate Change and Potential Impacts to Water Operations Levi Brekke (Reclamation, Technical Service Center) Presentation for the Bighorn River System Issues Group 29 July 2008, Lovell, WY

2. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent climate projections? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

3. “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level.” IPCC (2007) Working Group 1 Summary for Policymakers

4. Other Global Trends Global Mean Air Temperature Global average sea level Northern Hemisphere snow cover Fig. IPCC (2007)

5. Western U.S. Climate Temperature 1950-1997 trend (Mote et al. 2005) Precipitation 1976-2005 trend, “annual” inches/decade (www.cpc.noaa.gov/anltrend.gif)

6. Bighorn Basin region: NOAA “Climate Division” data http://www.cefa.dri.edu/Westmap/ Red = annual, blue = moving 25-year mean annual

7. http://www.cefa.dri.edu/Westmap/ Red = annual, blue = moving 25-year mean annual Historical Climate Division P data: WY-04 Bighorn

8. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent climate projections? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

9. Explaining Temperature Trends “Attribution” Studies Model past Climate for two cases: –~All past “forcings” –Only past natural “forcings” Compare Results to Obs. (globally)… –Need ~All “forcings” to explain observed Fig. Andrea Ray

10. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent “climate projections”? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

11. Making Climate Projections: steps before global climate modeling Econ/tech storylines emission scenarios atmospheric concentrations climate model GCM Fig. P. Chris Milly

12. Show energy moving from equator to poles through hydrologic cycle. –Huge amounts of water and heat move around the planet –Evaporation, Ocean Currents Global Climate Modeling objectives

13. More certain results: Temperature Fig. IPCC (2007)

14. Atmospheric water content anomaly, 30S-30N over ocean; GFDL GCM; SMMR,SMM/I observations (Held and Soden, 2006) More certain results: Atmospheric Water, large areas Fig. P. Chris Milly

15. Less certain results: Precipitation, local/regional areas Fig. David Yates

16. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent climate projections? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

17. Fig. IPCC (2007) Temperature, three “scenarios”, results from multiple models

18. Change in mean-annual (%), 2090-2099 from 1980-1999 Fig. IPCC (2007) Precipitation, one “scenario” (A1b), results from multiple models

19. Downscaling: relating GCM outputs to local/regional change Developers –Santa Clara University (Ed Maurer) –Reclamation –LLNL Funding –Reclamation –DOE NETL http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/

20. Archive Scope Variables –Precip rate (mm/d) –Mean Daily Temp(°C) Attributes –Monthly, 1950-2099 –1/8°, contiguous U.S. Model Membership –projected SRES paths A1b, A2, B1 –Simulated past climate (i.e. “20th Century Climate Experiment”) …led to 112 projections selected for inclusion in archive #WCRP CMIP3 Model I.D.# A1b# A2# B1 1BCCR-BCM2.0111 2CGCM3.1 (T47)1…5 3CNRM-CM3111 4CSIRO-MK3.0111 5GFDL-CM2.0111 6GFDL-CM2.1111 7GISS-ER12, 41 8INM-CM3.0111 9IPSL-CM4111 10MIROC3.2(medres)1…3 11ECHO-G1…3 12ECHAM5/MPI-OM1…3 13MRI-CGCM2.3.21…5 14CCSM31…41…3, 5…7 1…7 15PCM1…4 2…3 16UKMO-HadCM3111

21. Change in mean-annual T (ºC), 2041-2070 from 1971-2000, middle change among 112 projections, at every downscaled location

22. Change in mean-annual P (in/yr), 2041-2070 from 1971-2000, middle change among 112 projections, at every downscaled location

23. Focusing on Bighorn area… 1). From website, download monthly “mean- area” T air & P time series for all 112 projections. 2). Compute historical-to- future period changes in mean-annual, mean-area T & P for every projection. Use 1971-2000 as historical reference period.

24. Consider spread of projected changes foro T and P individually. (Highlighting10 and 90 percentile changes…) 2010-20392040-2069 2070-2099

25. Now consider spread of paired changes… yellow-area shows intersected 10/90 percentile ranges 2010-20392040-2069 2070-2099

26. Consider spread of paired changes in T and P 2010-20392040-2069 2070-2099

27. Consider spread of paired changes in T and P 2010-20392040-2069 2070-2099

28. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent “climate projections”? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

29. Potential Natural Impacts Based only on warming… –less snowfall, more rainfall  –less snowpack, more runoff during winter  –less snowpack, less runoff during spring  –less snow area, more watershed participating in winter runoff events relevant to local flood control –earlier greenup, longer growing seasons –increased crop water demand based on T increase But, not sure whether CO2 increases will counter/amplify –warmer aquatic environments

30. Projected Runoff Impacts… “nearby” basin (Upper Missouri) Reclamation R&D study (FY08, ongoing) Collaboration with Univ CO, Univ AZ, NWS Missouri Basin RFC and Colorado Basin RFC

31. Missouri above Toston: Change in Annual T-Norms

32. Missouri above Toston: Change in Annual P-Norms

33. Missouri above Toston: Change in Annual Flow-Norms

34. Missouri above Toston: Change in Monthly T-Norms

35. Missouri above Toston: Change in Monthly P-Norms

36. Missouri above Toston: Change in Monthly Flow-Norms

37. Potential Operations Impacts Less “controllable” water supply if… –Increased winter runoff (decreased spring runoff) combined with no reduction in winter flood-space causes winter runoff to be spilled rather than conserved Different release schedules to accommodate… –earlier greenup, longer growing seasons –Changes in crop water demand –Management of aquatic environments under warming Others?

38. Outline 1.Is climate changing? 2.Are we affecting it? 3.Can we predict it? 4.Recent “climate projections”? 5.Impacts to hydrology and operations? 6.Factoring it into longer-term planning?

39. No START Question 7) Should effects disclosure be based on projected climate change? Option 4: Quantitative Sensitivity Analysis… Option 5: Quantitative Effects Analysis, where disclosure is based on a projected climate scenario rather than continued recent climate Option 1: No Analysis Question 6) Is look-ahead more than ~15 to 20 years? Significant Sensitivity? Question 1) Is climate relevant to the proposed project? Question 2) Is look-ahead relevant on a climate change time scale? Question 3) Are regional projections of climate change available? Option 2: Literature Review… Question 4) Do regional projections suggest significant change? Question 5) Is it preferable to follow lead of partner agency? No Yes IPCC 2007: (a) climate is generally assessed over a 20- to 30-year period; (b) climate change is generally measured as statistical changes between periods of 10 years or longer. (http://ipcc- wg1.ucar.edu/wg1/Report/AR4WG1_Pub_Annexe s.pdf) Option 3: Qualitative Analysis… Option 6: Follow lead of Partner-Agency END Options 4 and 5 include the same Literature Review as in Option 3. No Don’t Know No Yes No Yes Some scoping questions for factoring climate change into planning analyses… Reclamation has recent experience with Options 3 and 4 All Regions, TSC MP, PN, TSC

40. Given: Climate projection(s) of monthly T and P (downscaled) Natural Responses, Social Responses, Operational Constraints Operations Response Operations-dependent Response “Bracketing” climate projections… Analyzing Operations under Climate Change (Option 4 example, MP OCAP/ESA study) Rainfall-runoff simulation analysis under each climate projection... Operations modeling followed, reflecting supply changes under each projection. Delta levels, Delta water quality, and reservoir water temperature modeling Consumptive Use modeling wasn’t done… choice was rationalized assuming that demands wouldn’t necessarily change at “district-level” given management flexibility. No operations constraint adjustments made (e.g., monthly flood control rules, environmental/instream demands) http://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendices, Appendix R

41. Climate Projection Selection: Rationale developed for MP OCAP Given: available downscaled projections –http://gdo-dcp.ucllnl.org/downscaled_cmip3_projections/ We don’t know the “right” projections, therefore consider all CMIP3 projections as fair game. –We cannot classify emissions paths as more/less likely. –Its not obvious how to classify GCMs as better/worse. Gleckler et al. 2008, Reichler et al. 2008, Brekke et al. 2008 –Projections uncertainty doesn’t necessarily diminish after determining a “worse” set of GCMs and discarding their projections. Brekke et al. 2008 http://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendices, Appendix R

42. Projection Selection Factors 1.Periods: Future and historical (planning look- ahead determines future) 2.Climate Metric: for assessing “change” relevant to study (computed for all projections) 3.Location: where “spread” of changes from all projections is assessed, relevant to study 4.Change Range: subjective, within “spread” http://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendices, Appendix R

43. Projection Selection Factors: MP OCAP Choices 1.Periods: 1971-2000, 2011-2040 (consultation horizon is through 2030) 2.Climate Metric: Period Mean-Annual T air & P 3.Location: “Above Folsom” (sensitivity interest on change in water supply, Sierra Nev. runoff) 4.Change Range: 10 to 90 %-tile  T air,  P (desire to represent broad set of possibilities) http://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendices, Appendix R

44. Implementing Selection Factors: Step 1) Survey projections “Above Folsom” 1a. From website, download monthly T air & P time series. 1b. Compute historical and future period “climate metrics” for every projection. 1c. Compute historical-to- future period changes in “climate metric” for every projection. http://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_2008.html#appendices, Appendix R

45. Step 2) Identify rank-threshold  T air and  P http://www.usbr.gov/mp/cvo/ocapBA_20 08.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_20 08.html#appendices, Appendix R

46. Step 3) Overlay rank-threshold  T air and  P on scatter paired changes http://www.usbr.gov/mp/cvo/ocapBA_20 08.html#appendiceshttp://www.usbr.gov/mp/cvo/ocapBA_20 08.html#appendices, Appendix R

47. Result: range of future climates represented by set of bracketing projections

48. Questions? Levi Brekke Reclamation, Technical Service Center lbrekke@do.usbr.gov