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Pala Riparian Ecosystem Meeting 9/17/2015
Planning for climate change
on top of already high climate variability
Dan Cayan
Scripps Institution of Oceanography, UC San Diego
USGS Water Resources Discipline
much support from Mary Tyree, Guido Franco and other colleagues
Sponsors:
California Energy Commission
NOAA RISA program
California DWR, DOE, NSF
Great year-to-year variability in California precipitation
Southern California Coast area average shown here from Western Regional Climate Center
)
• Annual precipitation ranges from ~33% to 280% of average
• Intermittant very wet and very dry years
• Multi-year wet and dry spellls
High variability of weather and short term climate will continue
California records some of Nation’s heaviest 3-day rainfall
Locations that have recorded
the highest 3-day precipitation
amounts
Numbers of non-overlapping
3-day precipitation totals at
COOP weather stations
that exceeded 40 cm (15.75”)
from 1950-2008.
Atmospheric Rivers
West Coast flood generators
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virtually all climate simulations project warming,
but with a wide envelope of temperature change
July Temperature change Sacramento
+3°C
CMIP5 GCMs project +23.5°C summer warming by
2060, under mid and high
RCPs
14 GCMs X 3 RCP Emissions
th
Scenarios IPCC 5 Assessment
(CMIP5) models
Some important questions:
Which emissions pathway will we
take?
How much summer amplification
of warming?
How will temperature change in
near term?
average summer
afternoon temperature
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average summer
afternoon temperature
GFDL A2 1km downscaled to 1km
Hugo Hidalgo Tapash Das Mike Dettinger
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Projected change temperature and precipitation
31 Global Climate Models RCP 8.5 Los Angeles region
S
C
a
wetter
a warmer future
but uncertain
changes in precipitation
warmer
Projected change temperature and precipitation
31 Global Climate Models RCP 8.5 Los Angeles region
wetter
a warmer future
but uncertain
changes in precipitation
warmer
Projected change temperature and precipitation
31 Global Climate Models RCP 8.5 Los Angeles region
wetter
a warmer future
but uncertain
changes in precipitation
warmer
Heat Waves
Projected in San Diego
SRES A2 and SRES B1 GHG
Emissions Scenarios
Number of Days (n), April–
October, When Maximum
Temperature (Tmax) Exceeds
the 98th Percentile Historical
(1961–1990) Level of 82°F at
San Diego from Four BCCA
Downscaled GCMs. Brown
carrots and red dots shown for
B1 and A2 emission scenarios,
respectively. Thick brown (B1)
and red (A2) lines show median
value from the four simulations.
April through October number of days above the historical (1961-1990) 98th
percentile maximum temperature for 4 global climate models (cnrmcm3, ncarccsm3,
gfdlcm2.1, ncarpcm1) from BCCA downscaling for sresa2 (red) and sresb1 (brown).
Heavy lines indicate median number of days (per year). 98th percentile values range
from 81.7 oF to 82.9 oF.
Projected patterns of precipitation changes
2090-2099 versus 1980-1999
Globally, dry regions become drier
including the Southwest United States!
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Coastal Marine Stratus
Peak Cloudiness Timing
Aug
Jul
Jun
May
Difference: Morning - Afternoon
Low Cloud Frequency (%)
October 26, 2003
dry fuels
+ low humidity + winds
makes extreme fire danger
October 2003: Major Santa ana conditions
13 major fires in CA& Mex.
> 300K hectares (750K acres)
24 lives lost
239 injured
4866 structures lost
> $2 billion in insured losses
$176 million in disaster relief
$116 million in suppression costs
Largest fire (Cedar) and largest fire siege in
California history
Increased SoCal fires since 2000-a temporary rise or a trend?
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Summary
• California’s climate is prone to year-to-year and longer term variation in precipitation—
drought is an expected part of our climate—present and future.
• California dry spells often build up over multiple years,. A more/less dry pattern has
been in place since 1999. A variety of climate patterns may produce drought--there
is not a unique atmospheric drought-circulation pattern.
• The absence of a few very large storms is often a key driver of dry years. And large
storms are frequently involved in “busting” drought.
• Climate change will broadly affect California hydroclimate and impact sectors and
systems across-the-board. Expected impacts of climate change: longer “warm”
season, loss of spring snow pack, increased wildfire threat, more winter floods.
• Climate changes in annual precipitation is not so clear in California. However,
climate change may shift precipitation characteristics—fewer overall wet days but
more intense heavy events. Climate change projections—warmer, fewer overall
wet days but more intense heavy events.
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CEC Workshop Sacramento 8/28/2015
El Nino 2015
will it alleviate the 2012-2015 drought?
Dan Cayan
Scripps Institution of
Oceanography, UC San Diego
USGS Water Resources Discipline
much support from David Pierce,
Mary Tyree, and other colleagues
Sponsors:
California Energy Commission
NOAA RISA program
Southwest Climate Science Center
U.S. Army Corps of Engineers
Only two wet years
2007-2015
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since 1977 average temp
in SoCal has been warm
2014 and 2015
exceptionally warm!
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The California Drought
the drought took hold in 2012
and intensified through 2015
Global SST Departures
o
( C)
During the Last Four Weeks
During the last four weeks, equatorial SSTs were above average across the central and
eastern Pacific and the Indian Ocean, and below average in the Atlantic Ocean.
Very warm surface waters now in Eastern Pacific Ocean
NOAA
Niño Region SST Departures
o
( C) Recent Evolution
The latest weekly SST
departures are:
Niño
Niño
Niño
Niño
NOAA
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3.4
3
1+2
1.1ºC
2.1ºC
2.2ºC
1.7ºC
Tropical Pacific has warmed considerably-- El Nino has set in
Sub-Surface Temperature Departures in the Equatorial
Pacific
During the last two months, positive subsurface
temperature anomalies were observed across most
of the equatorial Pacific
Most recent pentad analysis
Recently, negative anomalies were evident in the
far eastern Pacific and western Pacific, while
positive anomalies have persisted across the central
and eastern Pacific.
NOAA
Central and Eastern Pacific Upper-Ocean (0-300 m)
Weekly Average Temperature Anomalies
During January – March, a significant sub-surface warming occurred across the eastern
Pacific. Since March, sub-surface temperature anomalies have remained large, but
with some minor fluctuations in strength. Following a drop in June, the anomalies
increased in July. Since early August, positive anomalies have persisted.
NOAA
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SUMMARY
Rather strong El Niño conditions have developed in the
tropical Pacific. El Niño will likely remain in place through
winter 2015-16.
If winter El Niño is strong, we could see above normal
storminess in Southern California and maybe Northern
California.
Historical El Niño’s have resulted in a wide range of
California precipitation during the water year. Strongest
odds of wet winter in SoCal.
Historical El Niño’s have produced large Pacific storms
along with high waves and high sea levels along the
Calfiornia coast. Periods with highest tides would produce
strongest impacts if large storms were present
Frank Gehrke,
California Cooperative Snow Surveys, DWR
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