california climate change: a historical...

California Climate Change:California Climate Change:A Historical Perspective A Historical Perspective

Michael Anderson, Ph.D., P.E.Michael Anderson, Ph.D., P.E.California Department of Water ResourcesCalifornia Department of Water Resources

Division of Flood ManagementDivision of Flood Management

CH1 IntroductionCH1 IntroductionCH2 BackgroundCH2 BackgroundCH3 DWR StudiesCH3 DWR StudiesCH4 SWPCH4 SWP--CVP ImpactsCVP ImpactsCH5 Delta ImpactsCH5 Delta ImpactsCH6 Flood ManagementCH6 Flood ManagementCH7 EvapotranspirationCH7 EvapotranspirationCH8 Future DirectionsCH8 Future Directions

Peer reviewed chaptersPeer reviewed chapters

AcknowledgmentsAcknowledgments

Thanks to Jim Goodridge retired state Thanks to Jim Goodridge retired state climatologist, David Rizzardo, Matt climatologist, David Rizzardo, Matt Winston, Boone Lek, BG Heiland, Tawnly Winston, Boone Lek, BG Heiland, Tawnly Pranger, Aaron Miller, Maury Roos, John Pranger, Aaron Miller, Maury Roos, John King, and Steve Nemeth of DWRKing, and Steve Nemeth of DWR--DFM DFM and Jamie Anderson of DWR Delta and Jamie Anderson of DWR Delta Modeling.Modeling.

Presentation OutlinePresentation Outline•• Introduction Introduction

•• Historical Data Historical Data

•• Climate ChangeClimate Change

•• Impacts AssessmentImpacts Assessment

IntroductionIntroduction

•• Climate vs. Weather Climate vs. Weather –– ““Climate is what Climate is what you expect and weather is what you getyou expect and weather is what you get””Mark TwainMark Twain

•• Global Climate Models aim to predict Global Climate Models aim to predict climate not weatherclimate not weather

•• Individual weather events may vary greatly Individual weather events may vary greatly for a given climatefor a given climate

IntroductionIntroduction•• Looking back to frame a look aheadLooking back to frame a look ahead•• Examine historical record for Examine historical record for

trends and variabilitytrends and variability–– TemperatureTemperature–– PrecipitationPrecipitation–– RunoffRunoff–– Flood PeaksFlood Peaks–– Sea Level RiseSea Level Rise

•• How does variability compare to trends?How does variability compare to trends?

Historical TemperatureHistorical Temperature•• Statewide average observed warming of about 0.5 Statewide average observed warming of about 0.5 °°C (1 C (1 °°F)F)

40

50

60

70

80

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Tem

pera

ture

(deg

F)

Maximum Average Minimum

Historical PrecipitationHistorical Precipitation

•• Statewide Average Precipitation: Lots of variability, no trendStatewide Average Precipitation: Lots of variability, no trend

0

10

20

30

40

50

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year

Prec

ipita

tion

(inch

es)

1915-1935:20.8 inches

1980-2000:25.6 inches

1890-2000:23.9 inches

Historical Runoff TimingHistorical Runoff Timing

Sacramento River System

Water Year Runoff

0

8,000

16,000

24,000

32,000

40,000

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Water Year (October 1 - September 30)

Run

off V

olum

e (tA

F)

Historical Runoff TimingHistorical Runoff Timing

April-July Runoff

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Water Year (October 1 - September 30)

Run

off V

olum

e (tA

F)

Sacramento River System

Historical Runoff TimingHistorical Runoff TimingSan Joaquin River System

Water Year

02,0004,0006,0008,000

10,00012,00014,00016,000

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Water Year (October 1 - September 30)

Run

off V

olum

e (tA

F)

Historical Runoff TimingHistorical Runoff TimingSan Joaquin River System

April - July Runoff

0

2000

4000

6000

8000

10000

1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001

Water Year (October 1 - September 30)

Run

off V

olum

e (tA

F)

Changes in Annual Peak RunoffChanges in Annual Peak Runoff

165/489165/48952/9152/91145/232145/232RangeRange

48/8448/8411/1911/1933/5033/50Standard Standard DeviationDeviation

93/12393/12312/1712/1742/5242/52MeanMean

EelEelTuolumneTuolumneFeatherFeatherPre/Post Pre/Post 19551955

Values in 1000 cfs for annual peaks of 3-day average flows1904-2004 data used for analysisRange is maximum-minimum values for time period

Sea Level RiseSea Level Rise

Golden Gate

Golden Gate

A look aheadA look ahead……

Climate change model information Climate change model information from Global Climate Modelsfrom Global Climate Models

Projected Changes TemperatureProjected Changes Temperature

From Dettinger, 2005Some Uncertainty

Projected Changes PrecipitationProjected Changes Precipitation

From Dettinger, 2005Lots of Uncertainty !

Impacts Assessment Impacts Assessment -- HydrologyHydrology

•• Examine possible impacts of increases in mean Examine possible impacts of increases in mean atmospheric temperature of 1atmospheric temperature of 1--55°° CC

•• Assume Assume snowpacksnowpack retreats at 500 feet per 1retreats at 500 feet per 1°° CC

2030405060708090

100

0 1 2 3 4 5

Avg. Atm. Temp. Increase ( C)

Perc

ent S

now

Fre

e

Above Shasta Above Oroville Above Folsom

Snowpack Reduction ImpactsSnowpack Reduction Impacts

Storm Runoff Impacts Storm Runoff Impacts •• Higher snow levels yield more direct runoff per stormHigher snow levels yield more direct runoff per storm

0.0

0.5

1.01.5

2.0

2.5

0 12 24 36 48 60 72 84 96 108

120

132

144

Hour

Scal

ed R

unof

f

Base Case 1 degree increase3 degree increase 5 degree increase

Impacts AssessmentsImpacts Assessments•• Initial AssessmentsInitial Assessments

–– CVP/SWP Operations CVP/SWP Operations –– Dan Easton (DWR)Dan Easton (DWR)

–– Delta Issues Delta Issues –– Jamie Anderson (DWR)Jamie Anderson (DWR)

•• Ensemble Methods Ensemble Methods –– The next stepThe next step–– CVP/SWP Operations Impacts with Ensemble CVP/SWP Operations Impacts with Ensemble

Analysis Analysis –– Levi Brekke (USBR)Levi Brekke (USBR)

–– Weighted Estimation of Projection Weighted Estimation of Projection Distributions Distributions –– Levi Brekke (USBR)Levi Brekke (USBR)

Questions ?

Web Page: Web Page: http://http://www.climate.water.ca.govwww.climate.water.ca.govEmail: Email: climate@water.ca.govclimate@water.ca.gov