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Dan Cayan Scripps Institution of Oceanography, Climate Research Division, UCSD and Water Resources Division, USGS Thanks: Mike Dettinger, Noah Knowles,

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Presentation on theme: "Dan Cayan Scripps Institution of Oceanography, Climate Research Division, UCSD and Water Resources Division, USGS Thanks: Mike Dettinger, Noah Knowles,"— Presentation transcript:

1 Dan Cayan Scripps Institution of Oceanography, Climate Research Division, UCSD and Water Resources Division, USGS Thanks: Mike Dettinger, Noah Knowles, Mary Tyree Californias Future Climate Lessons from Scenarios Assessments Funding: PIER Program, California Energy Commission RISA Program, NOAA Office of Global Programs DOE More info: http//

2 Gov Swartzeneggers June 2005 Executive Order commissioned this Climate Assessment, which investigated potential climate change impacts and formed key scientific background for Californias greenhouse gas emissions legislation, AB-32 which was passed in fall 2006 Available on the web at iennial_reports/2006report/ California Climate Change Scenarios Assessment some lessons learned

3 Vulnerability: response to a +3ºC warming What fraction of each years precipitation historically fell on days with average temperatures just below freezing? Rain vs Snow More vulnerable YOSEMITE Computed by Mike Dettinger from gridded historical US weather data (from Bates et al, in rev) Less vulnerable

4 Winter (Nov-Mar) SFE/P trends at western US weather stations: symbol area is proportional to study-period changes, measured in standard deviations as indicated; circles indicate high trend significance (p 0.05). More Rain Less Snow WY Noah Knowles et al in press J. Climate

5 We face significant losses of spring snowpack By the end of the century California could lose half of its late spring snow pack due to climate warming. This simulation by Noah Knowles is guided by temperature changes from PCMs Business-as- usual climate simulation. (a middle of the road emissions scenario) Less snow, more rain Particularly at lower elevations Earlier run-off More floods Less stored water Knowles and Cayan 2001

6 since 1985 the number of large wildfires in western U.S. increased by 4X Anthony Westerling et al. Science August 2006

7 Large wildfire threat is aggravated by warmer springs and summers Anthony Westerling et al. Science August 2006

8 Ocean Beach, February 1983 Extreme storm-forced sea levels during an extreme tide

9 Observed SFO (left) and modeled Global (right). Sea level rise estimates based upon an envelope of output from several GHG emission scenarios observed Projected envelope of global s.l. rise Climate models Only provide loose guidance on The amount of sea level rise, but It is very likely that rates will increase

10 San Francisco Bay/Delta Water Levels Confluence of sea level rise and increased flooding ~Jan Nasa /ncalifflood_amo_ _lrg.jpg

11 Uncertainty: Projected Warming Ranges Statewide annual average (°F) Lower Warming Range Medium Warming Range Higher Warming Range Temperature Change (°F)

12 Meditterranean precipitation regime remains

13 Although models unanimously indicate a warmer climate, they are undecided if it will get wetter or dry out 6 different climate models 5 emission scenarios, IPCC SRES runs Mike Dettinger, 2005 San Fran. Estuary and Watershed Science

14 Projected patterns of precipitation changes versus Globally, dry regions become drier?

15 Mike Dettinger, Jim Wells USGS and SIO record streamflow in Tuolumne Meadows Challenges

16 Seasonally intensified warming? some models suggest amplified summer warming

17 Climate models project C ocean surface warming by end–of-century. Greater warming on land than oceans would amplify California coast-interior thermal gradient. Summer land warming is accentuated GFDL CM2.1 Jun-Aug air temp change minus GFDL CM2.1 is a medium-high sensitivity model. Other models produce less (or more) warming

18 Modeling climate over Californias complex terrain: July 10m Wind Diurnal Variation

19 Hist means (inches): Div Gfdl Pcm Are models capable of producing realistic suite of wet and dry spells? Distribution of Obs and simulated 5yr precip departures obs sim Sacramento drainage div

20 California needs a sustained modern Climate Observation Network Douglas Alden Scripps Institution of Oceanography Installing met station Lee Vining, CA

21 Implications for Monitoring Primary snowpack loss is above ~1500m Knowles and Cayan, 2004

22 Total number of stream gages below 1500m (red) Total number of HCDN gages below 1500m (red) Total number of gages above 1500m (blue) Total number of HCDN gages above 1500m (blue) Rain-snow transition zone Needs more Careful monitoing Over all Stream gages, present-day elevational bias is small… …but climate-quality HCDN subset is under-represented in crucial elevations. Noah Knowles, USGS)

23 …on the other hand, it can be very wet May 16th 2005 A warm storm in the Sierra Yosemite Valley floods from a 1 rain Yosemite Valley floods from a 1 rain

24 need to understand event scale phenomena projected heat wave days SRES A2 GHG Emissions Scenario

25 Slide 11 Need observations of 3-d, upstream atmosphere Hydromet testbed, NOAA ETL and collaborators

26 How to effectively work and learn across disciplines? Scenarios, not forecasts PCM. GFDL, HAD Model-based Climate Projections Agriculture Water Energy Forests/ Fire Coping Capacity/Preparedness Impacts -Physical -Ecological -Economic -Social Human Health Coasts Susi Moser, NCAR

27 Recommendations (without much discussion) : Improved, sustained observations higher spatial resolution, more coverage 3-d atmosphere and ocean upstream California meso-micro climates including urban and agricultural settings improve insitu network, real-time communications scientific quality record keeping of economic, social measures data archeology Continued modeling at several scales, disciplines Ongoing climate simulation compute consortium Ongoing Consortium for climate simulation/prediction to knit state/campuses/labs End-to-end assessments, including eco, economic, social; close State participation Study extreme events as well as secular changes Study aerosol-clouds-precipitation Link with other regional, national, international efforts Support California State Climate Scenarios Assessments Promote CEC-PIER Annual Climate Change Conference Develop closer, better links to decision makers; strengthen outreach Fellowship program for grad students, post docs to ensure continuity, new generation

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