ARkStorms amp the Sierra Nevada Mike Dettinger US Geological Survey Scripps Institution of Oceanography Dale Cox US Geological Survey Sacramento NOAAs CaliforniaNevada Applications Program ID: 425726
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Slide1
Climate Change,
ARkStorms & the Sierra Nevada
Mike Dettinger, US Geological Survey, Scripps Institution of OceanographyDale Cox, US Geological Survey, Sacramento
NOAA’s
California-Nevada
Applications ProgramSlide2
Dettinger
, SFEWS, 2005
PROJECTED CHANGES IN ANNUAL TEMPERATURES,
NORTHERN SIERRA NEVADA
PROJECTED TEMPERATURE CHANGES
-4F
20 of 23 in this range
0F
+
4F
+
8
F
12FSlide3
All Drier
All Wetter
Among 12 projections with
high-CO2
emissions,
how many models yield increasing (decreasing) precipitation?
PROJECTED PRECIPITATION CHANGES
Northern California still on the edge between more-or-less precipitation.
Percentage Change from Historical NormalsSlide4
PROJECTED SNOW
CHANGES
Courtesy of David Pierce, SIO
End snow
szns
(
9 CMIP5 RCP4.5 GCMs BCCA downscaled, VIC snow simulated)
Rain
vs
Snow
More change
NO change
Start snow
szns
Dettinger & Culbertson, SFEWS 2008
More rain
vs
snow
Shorter snow-cover seasons
Earlier snowmelt & runoffSlide5
Cayan
et al., SWCA, 2013
16 models, A2 emissions
Northern Sierra Nevada
Median of A2 emissions
Median of B1 emissions
Center of sliding 50-yr window
Percentage of historical 50-yr flood
Das et al.,
ClimChg
, 2012; JH, in rev
PROJECTED STREAMFLOW CHANGES
Distributions of 50-yr flood
changesSlide6
PROJECTIONS of MONSOONS/FIRE-WEATHER
June-September, 2041-69
vs 1971-99Precipitation TemperatureJune-October, 2080-99 vs 1980-99Moist Static Energy
Reductions in summer precipitation?
(Mearns et al. 2009)
Later monsoon arrivals & withdrawals (Cook & Seager, 2013)
More stable atmosphere, less thunderstorming (Cook &
Seager, 2013)Slide7
50-yr Floods
PROJECTIONS of
LARGEST WINTER STORMS (Atmospheric rivers, or pineapple expresses)Update to Dettinger, JAWRA, 2011Slide8
Short-Term (during & immediately following storm)
Flooding along streams & in meadows
Wind damage to structuresDeep wet snows/traffic interruptions, around Lake & to/from Lake
Infrastructure damages/utility interruptions
Trashed snow runs
Erosion, sediment & nutrient transports into Lake
Wind-blown tree falls
Dilution of upper layer of Lake?
“
ARkStorm
”
Consequences at Lake TahoeSlide9
Long-Term (month to years following storm)
Deep wet snows / continuing traffic interruptions to/from Lake (e.g., 1986)
Continuing utility interruptionsTrashed snow runsExpensive repairs & economic recoveries
Forest/meadow damages
C
ontinuing erosion/nutrient episodes
Major Lake clarity impact?
Repeated Lake clarity impacts?
Open-doors for invaders?
“
ARkStorm
”
Consequences at Lake Tahoe
Emergency
-Response
Desktop Exercises
coming
to
Tahoe
/Reno/CC region
, Winter
2014!Slide10
FROM CLIMATE/HYDRO MODELS &
OTHER CONSIDERATIONS, WE PROJECT:
Warming by +3 to +6ºC across Sierra, likely more so at higher altitudes Much of Sierra in range for modest, wetter-or-drier trends
Monsoons may be delayed/reduced
Extreme weather/floods gets more extreme
More rain, less snow
Less snowpack
Increased winter flood risks but longer low flows
Less overall
streamflow
(think -5 to -15%)
Changes in aquifer recharge
Longer growing seasons
More, more severe heat waves
Fewer (but deeper?) cold snaps
Increased wildfires
Favors many invasive speciesSlide11
11
For much more info on these & other topics, see the new 2013 Southwest Climate Assessment Report: http://www.swcarr.arizona.edu
Contact mddettin@usgs.gov w/questions or for info re: ARkStorm@Tahoe