Key California Issues in a Changing Climate from a State Perspective

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1 Key California Issues in a Changing Climate from a State Perspective Climate Scenarios and Projections: the Known, the Unknown, and the Unknowable as Applied to California March 11-14, 24 Aspen, Colorado Guido Franco

2 Outline Major Climatic Issues Other Factors A closer examination of two issues: Air Quality and Energy Conclusions

to the effect of urbanization and use of irrigation water.

3 What are the Trends for Temperature and Precipitation in California? Temperature trends seem to be clear but we do not have a definitive answer as to the effect of urbanization and use of irrigation water. Precipitation trends are not clear Grid Average Values Source: Groisman et al. Journal of Hydrometeorology. 24

4 Precipitation Trends Total Annual Precipitation vs. for Ukiah Precipitation (In Hundreths) Precipitation (In Hundreths) Precipitation (In Hundreths) Precipitation (In Hundreths) Total Annual Precipitation vs for Fresno WSO AP Total Annual Precipitation vs. for Santa Barbara Total Annual Precipitation vs for LA AP Weaverville 25 ft Fort Bragg 5 N Ukiah Sacramento San Francisco WSO AP Yreka 2526ft Santa Barbara Cedarville 467 ft Mount Shasta 359 ft Quincy 348 ft Los Angeles AP Lake Spaulding ft Tahoe City ft Fresno WSO Yosemite Park ft Cuyamaca 464 ft Independence ft Fairmont 36 ft Low Elevation High Elevation Precitptation (in Hundreths) Precipitation (in hundredths) Precipitation (In Hundredths) Precipitation (in hundreths) Total Annual Precipitation vs. for Yreka Total Annual Precipitation vs. for Lake Spaulding Total Annual Precipitation vs. for Yosemite Park Hdqtrs. Stn Total Annual Precipitation vs. for Cayamaca Source of Data: WRCC, USHCN

5 Are Aerosols Masking the Real Precipitation Trends in High Elevations? A new study by Amir Givati and Daniel Rosenfeld* strongly suggests that this is the case. Without aerosols the precipitation trends in high elevations would have been about 15 to 2 percent higher Urban Aerosol-Induced Changes of Precipitation Eos Trans. AGU, 84 (46) 23 Precipitation (in) Ro Ratio of Precipitation in High and Low Elevation Stations Cuyamaca - San Diego Historical Precipitation and Estimated Precipitation with Ro = 4 Cuyamaca Data Source: Western Regional Climate Center (WRCC) Ro = 4

6 Projected changes of Temperature and Precipitation It is very difficult to develop robust adaptation strategies* when we do not know if it is going to be wetter or drier Are there at least relatively narrow probability bands for the next few decades? Source: Scripps * Please note that this does not mean that no regrets options are not available Source: Scripps Source: Origins and estimates of uncertainty in predictions of twenty-first century temperature rise.nature. Vol April 22

7 Stream Flow Timing Increased risk of floods in the winter season Reduced flows in the spring Less water available in the dry summer season Total Monthly Mean Rim Inflow (TAF) T %P 1.5T 9%P 3.T %P 3.T 18%P 5.T %P 5.T 3P HCM HCM HCM PCM PCM PCM Historical Source: Lund et al. 23 PIER Report Calendar Month

8 Sea Level Rise Sea level rise could disrupt the conveyor system that brings fresh water from northern to southern California Increased sea water intrusion in coastal aquifers Source: 1998 State Water Plan. DWR

Potential changes in the frequency and amplitude of natural mode of climate oscillations Two of the strongest El Niño events in the last 1 years have occurred in the last decade.

9 Potential changes in the frequency and amplitude of natural mode of climate oscillations Two of the strongest El Niño events in the last 1 years have occurred in the last decade. Would storminess increase in California? There is a danger of maladaptation if we confuse natural oscillations as a climate change signal. Source: Bromirski, Flick, and Cayan. 23

10 Loss of water storage capacity in the Sierra On April 1 st DWR determines how much water stored in snow is available for the dry season. Most studies estimate substantial reductions of April 1 st snow cover. Snow Cover Source: Scripps

11 The potential ecological impacts are enormous California is a hotspot for biodiversity Some ecological systems (e.g., coastal sage scrub*) may only survive in a few places A preliminary PIER study** suggests that managed systems can adapt at cost but this may not be the case for ecosystems *Home of about 1 endangered or potentially threatened species ** Source: Myers et al. Nature Vol. 43. Source: Smith et al. 23 PIER Report

12 Other Factors Transport of air pollutants from Asia Urbanization Increased population Invasive species Surprises Landis et al. 23 PIER Report

13 Data Source: WRCC, ARB, and CIMIS Air Quality: a Closer Examination (Ozone) O 3 vs. Maximum Air Temperature for Fresno ( ) We assume that higher temperatures will increase ozone levels but. Some Air Districts are reporting a trend towards more days conducive to ozone production. Would this create a problem achieving the national and state ambient air quality standards in the next 2 to 3 years? O3 (ppm) Max Air Temp. ( F) Max Air Temperature Max. Air vs. Temperature Solar Radiation ( o F) for Fresno (Jun-Oct ) Solar Radiation (Ly/day) Monthly Averaged Maximum Temperature Trends: August Red = increased trend Temp. ( o F) Tmax & Tmin August for Hansford 1S ( ) T max T min

14 Air Quality: A Closer Examination (Particulate Matter) PM1 vs Precipitation for Fresno ( , Nov-Mar) In California ammonium nitrate (NH 4 NO 3 ) dominates wintertime PM levels PM1 (µg/m 3 ) Precipitation levels have a strong influence on measured PM levels Precipitation (in) Average Precipitation and Particulate Matter: San Joaquin, Stanislaus, Merced, and Fresno Counties Nitrates go down with increased ambient temperatures NH 3 (g) + HNO 3 (g) NH 4 NO 3 (s) Precipitation (in) PM1 (microgram/m 3 ) PM1 (annual arithmetic average) Precipitation Temperature Data Source: ARB, WRCC

15 Energy: A Closer Examination The urban heat-island effect may be as important as climate change for energy demand. Most studies use projected average temperatures or CDD/HDD to estimate energy demand. This is problematic due to the expected asymmetric changes in diurnal temperature profiles Normalized Cooling Degree Days Data Source: NOAA ( ) ( ) ( ) ( ) (1971-) Sacramento Fresno San Fran Airport Long Beach Burbank San Bernardino San Diego Yreka Blythe CDD = _[(Tmax+Tmin)/2 65 F] Where: (Tmax +Tmin)/2 > 65 F

16 Conclusions Retrospective analyses are extremely important. We need data at adequate temporal and geographical resolutions compatible with the analysis in hand. Probabilistic regional climate projections will help state planners. Uncertainty will remain with us for a long time Quantitative Knowledge useful for planning in California Time of Impact Next decades Issue Climatic Trends Climate Projections Potential Impacts on Managed Systems Potential Impacts on Unmanaged Systems Known Unknown* Unknowable >25 Climate Projections * To be discovered with further research in the next few years

Sierra Weather and Climate Update

Sierra Weather and Climate Update 2014-15 Kelly Redmond Western Regional Climate Center Desert Research Institute Reno Nevada Yosemite Hydroclimate Workshop Yosemite Valley, 2015 October 8-9 Percent of