1. California Climate Impacts Alex Ruane ESP Forum: Fall, 2006 From http://www.water.ca.gov/maps/allprojects.cfm

2. Unique aspects of California water management Observations of climate change on California’s water resources Climate scenario predictions for California Potential impact on California water resources Overview

3. From http://education.usgs.gov/california/maps/ Geography of California From http://www.water.ca.gov/maps/allprojects.cfm Population and agricultural centers are apart from rainfall maxima Major rivers State projects Federal projects Local projects

4. California Water System Lake Oroville: From http://orovillerelicensing.water.ca.gov/pdf_docs/bin2%20q5%20many%20photos.pdf Man-made reservoir operators must meet needs of: - Agricultural use - Municipal use - Domestic use - Hydropower Generation - Local and downstream wildlife - Recreational use - Flood prevention Canals carry water around state from local and distant sources All-American Canal: From http://www.usbr.gov/dataweb/html/allamcanal.html

5. California’s Natural Water System Snowpack in Sierra Nevada provide natural reservoir - Accumulate water during the winter - Melt during the spring and summer - Crucial to meeting California’s water needs From http://www.sierranevadaphotos.com/geography/snow_depth.asp From http://dommy.com/alan/pix/lone-pine.jpg

6. Changes in the onset of “springtime” (see Cayan et al., 2001) –Lilac and Honeysuckle blooms –First pulse of springtime runoff Distribution of Runoff: Biological changes Invasive species Increased fire risk Sea-level rise Observations of Climate Change in California From California Water Plan Update, 2005

7. Temperature, precipitation and snowpack are changing across the West –Regional changes –Interactions between natural variability and climate change caused by humans Water resources are shared across the region Observations of Climate Change in the West Changes in April Snow Water Equivalence, from Mote et al., 2005. From Mote et al., 2005.

8. Multiple pathways for the world –The Intergovernmental Panel on Climate Change (IPCC) has dozens of climate scenarios that express potential societal development – Changes can be both gradual and sudden Climate Scenarios Three scenarios for California explored in CA DWR Water Plan Update, 2005: –Current Trends –Less Resource Intensive –More Resource Intensive Changes from 2000 - 2030

9. Climate Scenarios The South Coast of California is very vulnerable under both the current trends and resource intensive scenarios Changes from 2000 - 2030

10. Climate Scenarios Percent changes in snowpack by elevation, from Hayhoe et al., 2004. Various computer simulations show an expected loss of CA snowpack in the future –Only extend to 2099 –Used A1fi (economically driven growth) and B1 (ecologically driven growth) IPCC scenarios –Particularly strong impact on lower elevations, models do not fully agree

11. Barnett et al., 2004: –Ran simulations using a coupled ocean/atmosphere model with the “business as usual” emissions scenario Assumes dominant societal focus is on growth –Regionally downscaled the results to focus on the Western USA Projected Impacts

12. By mid-century, Colorado River System will not be able to meet its demands –Reservoirs will be reduced by over 1/3 and releases by as much as 17% –Hydropower generation will be reduced by as much as 40% –The fully allocated Colorado system is “at the brink of failure” It will be impossible to meet current water needs in the Central Valley –Reduced reliability in water deliveries, hydropower, and river flow rates –A dramatic increase in salinity in the Sacramento Delta is possible In the Columbia River system (in WA and OR), policy-makers must choose between water for hydroelectric power or salmon runs, but not both Increased summertime temperature and reduced humidity are likely –Longer and more severe fire season –According to theory and many simulations (e.g. CA DRW studies), increases in evapotranspiration will result in higher irrigation needs Projected Impacts from “business as usual” scenario From Barnett et al., 2004.

13. In the size of natural and human-induced variabilities –There is still a significant spread in potential emissions scenarios and climate outlooks Which pathway will be chosen? –The West Coast of the USA is strongly influenced by interannual and interdecadal oscillations (ENSO, PDO, etc.) In the Models –Downscaling and regional outlooks are still difficult In the interactions between climate components –Snowpack vs. T –Snowpack vs. P –Snowpack vs. SST Uncertainties

14. Journal Articles –Barnett, T., R. Malone, W. Pennell, D. Stammer, B. Semtner, and W. Washington, 2004: ‘The effects of climate change on water resources in the West: Introduction and overview’. Climatic Change 62: 1-11 –Cayan, D.R., S.A. Kammerdiener, M.D. Dettinger, J.M. Caprio, and D.H. Peterson, 2001: ‘Changes in the onset of spring in the Western United States’. Bull. Am. Meteorol. Soc., 82(3): 399-415 –Mote, P.W., A.F. Hamlet, M.P. Clark, and D.P. Lettenmaier, 2005: ‘Declining mountain snowpack in Western North America’. Bull. Am. Meteorol. Soc., 86(1): 39-49 –Hayhoe, K., D. Cayan, C.B. Field, P.C. Frunhoff, E.P. Maurer, N.L. Miller, S.C. Moser, S.H. Schneider, K.N. Cahill, E.E. Cleland, L. Dale, R. Drapek, S.C. Sheridan, and J.H. Verville, 2004: ‘Emissions pathways, climate change, and impacts on California’. PNAS, 101(34): 12422-12427 –Miller, N.L, K.E. Bashford, and E. Strem, 2003: ‘Potential impacts of climate change on California hydrology’. J. of the American Water Resources Association (JAWRA) 39(4):771-784 California Department of Water Resources –Climate Change and California Water Resources: A Survey and Summary of the Literature, 2005 –California Water Plan Update 2005, 2005 –Progress on Incorporating Climate Change into Management of California’s Water Resources, 2006 References