Overview of New Extreme Heat Projections for California

Guido Franco*, Susan Wilhelm**

* Team Lead, Environmental Area (EA) Energy Generation Research Office

Research Division California Energy Commission guido.franco@energy.ca.gov

** Project Manager for the Energy Part of the Fourth Assessment susan.wilhelm@energy.ca.gov

Outline

• Probabilistic Projections for California Climate Zones: Regional variations and commonalities in temperature and precipitation

• Next-Generation Model Results (pending): What’s coming?

• Projected Regional High- and Low- Temperature Extremes

• Timing, Frequency, and Intensity of Heat Waves: Regionally Downscaled Projections as Represented by Cal-Adapt’s Extreme Heat Tool

2

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- 0.5 ~ - 0.5 ~ -1 -1.0 - 1.0 -2

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Probabilistic Projections for California Climate Zones

• “Probabilistic” climate projections for CA have been created using multiple global climate models and downscaling techniques

• Models predict warming throughout the state (rightward shift for all regions)

• Very wide range of uncertainty with regard to whether precipitation will increase or decrease (not certain what will happen) PRIOR GENERATION OF GLOBAL

and precipitation (mm/day, y axis) in DJF. Outer ellipse CLIMATE MODELS encloses 95% of the data; inner encloses 50%.

Joint distributions of change in temperature (deg C, x axis)

Pierce, D

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1950 1975 2000 2025 2050 2075

Next-Generation Model Results Using LOCA

• Increased spatial Annual average temperature for grid cell near SMF resolution (important for resolving community-level impacts)

• After year 2005, the green and red areas show projections.

• Very little difference in envelopes of variability associated with mid- and high-emissions trajectories before 2050.

Source: Franco and Oliver using data provided by David Pierce (Scripps)

4

NorCal coast

24 26 28 30 32 deg- C

Central coasl

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0.5

0.25 ( o'bs 0,01 ~-- - --~

26 30 34 311 dsg-C

Historical Future

SoCal coast

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deg-C

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deg- C

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deg- C

SoCal mtns

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32 36 40 deg- C

Northeast Cal

28 32 36 40 deg- C

Sierra Nevada ~;;J;V 0.75 0.5

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28 30 32 34 36 dsg-C

Inland empire

34 38 42 46 deg- C

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Heat Waves: Expect them to be Worse

For highest three-day average temperature:

• Temperatures get higher (illustrated as rightward shift of projected (blue) distribution relative to historical (red))

• Extreme high temperatures show disproportionate shift for inland areas, including Sierra Nevada, Inland Empire (shown as increasing distance between historical and projected

temperature for highs)

Pierce, D.W., et al. , 2013. Climate Dynamics, 40, 839-856. doi:10.1007/s00382-012-1337-9.

Figure: Cumulative distribution functions of the highest 3-day average temperature in the year. 5

♦---♦------------- ♦ ♦----- ...

----~~~~;;--

Historical Future

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Tmin(C)

San Joaq. valley

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Cold Snaps Persist

• Heating Degree Days* decreasing in the Central Valley, according to NOAA

• Recent research finds a trend of decreasing winter fog in the Central Valley (Baldocci and Waller 2014, Geophys Res. Letters)

– Clear nights can result in very low temperatures

• Even with warming trends, cold snaps would not disappear (2050 projections)

* Heating Degree Days are a measure of the degree and duration of cool weather

0

200

400

600

800

1000

1200

1400

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1950 1960 1970 1980 1990 2000 2010 2020

He

atin

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)

Year

Sacramento ValleyWinter MonthsSan Joaquin ValleyWinter Months

Data Source: NOAA

“ Winter fog is decreasing in the fruit growing region of the Central Valley of California “

2050

NASA

Figure: Cumulative Distribution Functions of January Daily Minimum Temperatures (Tmin) in Sacramento & San Joaquin Valleys. Note that low-end extremes are expected to persist in the face of climate change.

6

AVS

Gardenland, Sacramento, CA, USA

DAYS A BOVE 104.5°F

5 12 19 1961-19')0 2016-2046° 2046· 2076·

This chart displays a count of the number of days (along they

axis) that the selected area on map is projected to exceed the area's calculated Extreme Heat Threshold for each year under the

RCP 4.5 scenario.

RCP4.5 Etn1s.sions peak around 2040,

then dec:lme

RCPB 5

An eX1 -emc heat l::i def ned as day April 1hrough October w11e1e the max mum temper an.-. exceeds the 98th historic.a perceolIle of max mum

terr.pera1ures b1m!d on ob!IC'\'l!d daily temperatwe data between 1 96 1 1990

• N of extreme h t ya aYefaged over -Jl'.ren llme pe1i across all

higt,'9tted mod

Le.aHBI I Data: OSM. Map Tiles: Car1o0B, Georoding::

1900 1980 2000 2040 2060 2080

ss I 50 50

45 45

40 40

35 35

30 30

25 25

20 20

15 15

10 10

1960 1980 2000 2020 2040 2060 2080 21(0

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Projected Extreme Heat in Sacramento: LOCA Results for RCP 4.5 (mid-policy scenario, peak emissions ca. 2040)

Historical data Projected data Scale: up to 55 days/year

AV

Gardenland, Sacramento, CA, USA

DAYS ABOVE 104.5°F

5 14 28 1961 · 1990 2016 4 2046" 2046 · 2076·

This chart displays a count of the number of days (along they axis) that the selected area on map is projected to exceed the area's calculated Extreme Heat Threshold for each year under the

RCP 8.5 scenario.

RCP4.5 RCP 8.5 EmisS10ns continue to rise

strongly through 2050 and

plateau a-cuid 2100

An eKtreme ;ea1 day rs def oed as a day Apnl througt October where tne max Tlllm temperatwe en:ee1s the 8th historic.a per< l!l'1 c,f maxmum tel'!'4)eta"Mes based observ da temperature data betwffn 196 1990

•N..nbef fel('!reme'u>atdaysaveragedO'l'er ventimeperiodl'Cr01aall high ted model!!

LeaHe1 I Data: OSM., Map Ti les: Cal1008, Geo coding: Aapzen

1080 2040 2060 20B0 70 I 70

60 .. 50

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60

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lliifiil·I llfV.fl Miii'IW lifiMI Jdl IMiili'~I liUil'li:+I IIIIHHlil ■~IMli■ ICk amodel i:iht 1t. Show aa models

Projected Extreme Heat in Sacramento: LOCA Results for RCP 8.5 (continued “BAU” growth at 2%/yr)

Historical data Projected data Scale: up to 70 days/year

TEMPERATURE: EXTREME HEAT TOOL

11516 9th street sacramento ABOUT THE TOOL DI SCLAIMER & UNCERTAINTY

Timin g of Extreme Heat Days by Year OPTIONS

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A.nnua l t1111e step from 1950 to 2099

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Projected Extreme Heat in Sacramento: W i d e r season, higher extremes

Toward latter part of century, unprecedented extremes as high as 116 to 121 degrees F projected

Dramatically longer extreme heat season by century’s end.

Thank You! Extreme heat tool for LOCA results will be available soon on the beta-site of Cal-Adapt 2.0:

http://beta.cal-adapt.org/

Please send your comments, questions, and tell us how you are using the data:

support@cal-adapt.org

DISCLAIMER A staff member of the California Energy Commission prepared this presentation. As such, it does not necessarily represent the views of the Energy Commission, its employees, or the State of California. The

Energy Commission, the State of California, its employees, contractors and subcontractors make no warrant, express or implied, and assume no legal liability for the information in this presentation; nor

does any party represent that the uses of this information will not infringe upon privately owned rights. This presentation has not been approved or disapproved by the Energy Commission nor has the

Commission passed upon the accuracy or adequacy of the information in this presentation.