Holocene droughts, fires, floods and pluvials in southwestern California.

• Matthew Kirby• Professor, Cal-State Fullerton

• Dept. of Geological Science

• SCEC SoSAFE Workshop: Recent Successes and Future Challenges (Sept. 10, 2016)

• 13:30-14:00

STUDENTS.Special Thanks to:Christine Hiner, Joanna Fantozzi, Brittany Pyke, Pedro Monarrez, Bradley Markle, Shauna Nielsen, Lauren Rivera-Mirallegro, Luissa Ivanovici, Jenn Schmidt, Joe Carrasco, Michael Blazevic, Jose Rivera, Broxton W. Bird, Emily Silveira, Alex Woodward

FUNDING.Special Thanks to:National Science Foundation, American Chemical Society-Petroleum Research Fund, CSUF, Sigma Xi, Geological Society of America, Big Bear Municipal Water Authority, Lake Elsinore-San Jacinto Water Authority

Acknowledgements

COLLABORATORS.Special Thanks to:Sarah Feakins, Bill Patterson, Steve Lund, Susan Zimmerman, Michael Anderson, Scott Starratt, Glen MacDonald, Chris Scholz

Talk Organization

1. What is Paleoclimatology? And, How do we reconstruct past climate?

2. Holocene Climates in the coastal SW US

3. Relevance to Paleoseismology 4. Future Opportunities?

What is paleoclimatology?• paleoclimatology is the study of past

climate

Zaca Lake mud

How do we investigate past climate?• we use proxies contained in geological

archives to reconstruct past climate• geological archives include...

• ice cores• marine sediments• lake sediments• tree rings• cave deposits• coral

• a proxy is a substitute for a climate or climate related variable such as...• temperature• precipitation• atmospheric circulation patterns• ocean circulation patterns• flood events• fire activity• vegetation• geomorphic disturbance

Zaca Lake, CA (July 2009)

How do we investigate past climate?• I use proxies preserved in the sediment at the bottom of lakes/

wetlands (which, by the way, are rare in So Cal!) or any basin, really.• Sediments contain a combination of...

• weathered and eroded materials such as rock and soil...• materials produced within the lake such as phytoplankton

or chemically precipitated minerals (e.g., calcium carbonate)

• eolian materials such as dust, pollen, leaf waxes

Core LEGC03-4

flame structuresflame structures

erosional basal contactfingerprint

laminae

gradationalupper contact

Depth (cm)

330

329

317

318

319

320

321

322

323

324

325

326

327

328

Figure 5

Holocene Climates in the coastal SW US• Remarkably, our knowledge of past climate in the coastal

southwest US was extremely limited, until recently…• limited to some tree ring records (<1000 yrs), low

resolution sediment records, and packrat middens (Lynch 1931; Wells and Berger 1967; Ore and Warren 1971; Heusser 1978; Meko et al. 1980; Cole and Webb 1985; Enzel et al. 1989, 1992; Spaulding 1990; Rosen 1991; Brown and Rosen 1995; Cole and Wahl 2000; Biondi et al. 2001; D’Arrigo et al. 2001; Byrne et al. 2003)• note: I am not including the SBB records in this

talk• Relevant to this workshop are…

• Sediments that accumulate in basins - lakes, wetlands, sag ponds(?), etc…• often continuous• can capture annual to millennial scale

information• record geomorphic processes• are not limited to past 1000-2000 yrs, as are tree

rings• tree rings are extremely important archives

BUT they cannot tell us about • past floods, • geomorphic responses to climate such

as drought, • fire activity, • vegetation changes, • and many other things that are stored in

basin sediments…• And, they are also poorly represented in arid

environments like the coastal SW US• so, we need other sources of paleoclimatic information!

Kirby et al. in review Lake Elsinore mega flood event

4.8kyrs BP

Holocene Climates in the coastal SW US• Developed paleoclimate sites

• as relevant to this workshop and their value to the paleoseismic record

no tree rings no packrat middens

Lots of unknowns!

with tree rings no packrat middens

Still lots of unknowns!

• So, let’s take a virtual tour through time…

WARNING!!*lots of wiggles ahead

*lots of quick explanations

Holocene Climates in the coastal SW US

• Holocene perspective• Millennial scale

• Milankovitch (insolation) and large-scale Pacific ocean-atmosphere dynamics drive the signal

• Examples• Lake Elsinore (Kirby et al. 2004, 2005, 2007, 2010, 2013; Heusser et

al. 2015)• Dry Lake (Bird and Kirby, 2006; Bird et al., 2010)• Silver Lake (Kirby et al., 2015)

Holocene Climates in the coastal SW US

Silver Lake (Kirby et al. 2015)

3

2

1

0

-1

-2

1000 5000 9000 13000

Stn

dzd

percen

t cla

y

relative

lake

status

perennial

ephemeral

YD LM

II

BAEarly Holocene

Pluvial

Mid Holocene

Arid Interval

Late Holocene

EL

Age, cal yr BP

30

20

10

0-1

0

112

10

8

3

2

1

0

-1

-2

10

8

6

4

2

0

0

-2

-4

-6

-8

-101000 5000 9000 13000

Percent Sand

MoreEl Niños

LessEl Niños

SST (°C)

W -

E Pa

cific

SST

grad

ient

ano

mal

y (°

C)Weaker

gradient

Strongergradient

Perc

ent d

iff. s

umm

er/

win

ter i

nsol

atio

n fr

omm

oder

n at

30°

N

Stnd

zd p

erce

nt c

lay

relativelakestatus

perennial

ephemeral

YD LMII

BAEarly HolocenePluvial

Mid HoloceneArid Interval

Late HoloceneEL

ODP Site 1019(Barron etal., 2003)

Tropical Pacific(Koutavas andJoanides, 2012)

El Junco(Conroy etal. 2008)

(Las

kar e

t al.,

199

3)

Calendar Years Before Present

• Holocene perspective• Sub millennial to centennial scale

• Pacific sourced ocean-atmosphere forcing (ENSO, PDO) - evidence for climate state changes?• Holocene pluvials

• Examples• Lake Elsinore• PDO forcing

• Lower Bear Lake• Holocene pluvials• linked to changes in atmospheric river

frequency?

Holocene Climates in the coastal SW US

Lake Elsinore (Kirby et al. 2010)

Lower Bear Lake (Kirby et al. 2012)

• Holocene perspective• Sub Centennial to decadal scale

• Pacific sourced ocean-atmosphere forcing (ENSO, PDO)• data indicate real spatiotemporal variability• requires improved and quantitative wiggle matching• working with 2 CSUF statistics professors (Drs. Kevin

Nichols and Reza Ramezan) to quantify the patterns of climate change across different records with varying age control

• extending this comparison to aggregate tree ring records for the region• Examples• Zaca Lake• tropical Pacific forcing

• Abbott Lake (Kirby et al. in press)• tropical and N Pacific forcing

• Crystal Lake• a storm story linked to tropical and N Pacific forcing

Holocene Climates in the coastal SW US

Zaca Lake (Kirby et al. 2014; Feakins et al. 2014; Dingemans et al. 2014)

more run-off/wetter

less run-off/drier 9-

pt. s

moo

th p

erce

nt12

5 to

200

0μm

*regime shift detection from Rodionov, 2004 cy BP

Calendar Years BP0 1000 2000 3000

9-pt

. sm

ooth

per

cent

>125

to 2

000μm

0

2

4

6

A.

B.

More run-off/wetter

Less run-off/drier

200

400

600

μg/g

OC Dinosterol

(El Niño)

Cholesterol(La Niña)

C.

More intenseEl Niños/La Niñas

Fewer intenseEl Niños/La Niñas

LHDP(Mensing et al., 2013)IPCC LIA

IPCCMCA

Figure 9

F F F F F F F end of record

More El Niños

Fewer El Niños

Perc

ent S

and

0

10

20

30

Zaca Lake (Kirby et al. 2014)

Conroy et al., 2008

Makou et al., 2010

SBB flood events

• Holocene perspective• Annual scale

• generally a Pacific sourced ocean-atmosphere forcing…other things too (e.g. volcanism)• Examples

• Cook et al. (2004, 2009) PDSI reconstructions• how do these records relate to sediment based

reconstructions? Zaca vs. Tree Rings

Holocene Climates in the coastal SW US

Cook et al. (2004) Epic Droughts

data from Cook et al. (2004)

Zaca

>12

5 µm

sand

(9pt

. sm

ooth

)C

SWU

S PD

SI

Calendar Years Before Present

Dro

ught

Are

a w

este

rn U

S

IPCCLIA

IPCCMCA

DDD

D

WWWW 20

40

60

data from Cook et al. (2004)

way more epic

Relevance to Paleoseismology• “While several studies have compared paleoseismic event histories at neighboring sites to appraise

earthquake synchronicity (e.g., Onderdonk et al. 2013; Scharer et al. 2014), there have yet to be comprehensive studies that focus on the climatically-controlled geomorphic changes throughout the earthquake record.  For instance, are there simultaneous depositional or erosional events across regions of southern California that we can tie to an historical mega-flood or decade-long wet period?  If yes, as proposed by Grant-Ludwig et al. (2010) and Scharer et al. (2014), we can use sedimentary and pedogenic records of these geomorphic events as benchmarks to refine the paleoseismic record.” quoted directly from proposal by Salisbury and Arrowsmith (SCEC prop 2015)

Relevance to Paleoseismology• Clearly, paleoseismic sites

contain a wealth of paleoclimatic data…but, only if approached with the correct methodologies/protocols• sampling• dating• recovery time for climate

signal to establish post-disturbance

• coring will not work (see next slide)

Relevance to Paleoseismology• Example of issues…

Wow, what a beautiful section! -core #1

Hmmm, what an ok section.

-core #2

D’oh! what a crappy section! -core #3

*oh no! cores at this site would equal paleoclimatic failure!! *what’s the solution for working in seismically disturbed basins (e.g. sag ponds…) -paleoclimatologist and paleoseismologist must work together in the open trench to deconvolve the climatic and seismic history!

Future Opportunities?• Remember the slide with the tree and sediment sites?

• mostly empty• BUT, a lot of that emptiness can be filled using

paleoseismic sites where permanent lakes and trees are rare• climate is spatially and temporally complex…

• we MUST fill in the spatial and temporal gaps IF climate records are to be used as “benchmarks to refine the paleoseismic record”

• but, sediment-based paleoclimate work requires $$• So, where do these future collaborations find their

funding?

Thank You!10/0.5

20/8.0

30/15.5

40/23

50/30.5

60/38

70/45.5

80/53

90/60.5

100/68

110/75.5

TWTT

(ms)

/met

ers b

elow

lake

bot

tom

LE line 10

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900Distance (m)

seismic reflection line down the long axis of Lake Elsinore, CA (Kirby et al. in prep)