EXTREME WEATHER:
THE CONSEQUENCE OF CLIMATE CHANGE
More Wildfires
1950’s
2009
No Global
Warming
LONG-TERM ARIDITY CHANGES IN THE WEST
100
DRIER
% DROUGHT AREA
80
936 1034
60
WETTER
Longer
Droughts
40
20
0
1321
800
2010
1150 1253
900
2011
Record Lows
1613
1829
1915
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
YEAR
2012
Record Highs
Bigger Floods
PACLIM
March 3-6, 2013
ABSTRACTS
PRELIMINARY FINDINGS FROM LAKE SEDIMENT STUDIES OF CHANGING WATER
AVAILABILITY IN WESTERN NORTH AMERICA DURING THE HOLOCENE
Mark B. Abbotta, Byron A. Steinmanb, Michael E. Mannb, Lesleigh Andersonc, Joseph D. Ortizd, Bruce P. Finneye
a
Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260, USA
Earth System Science Center and the Department of Meteorology, Pennsylvania State University, University Park,
PA 16802, USA
c
US Geological Survey, PO Box 25046, DFC, Denver, CO 80225, USA
d
Department of Geology, Kent State University, Kent, OH 44242, USA
e
Department of Biological Sciences, Idaho State University, Pocatello, ID 83209, USA
b
E-mail address: mabbott1@pitt.edu
Over the last 20+ years we have learned a great deal about the timing and duration of droughts in western North
America from a network of tree-ring studies. Lake sediments offer a different perspective on drought and can
provide longer records at the cost of less precise chronologies. By combining information from both archives we
believe that the spatial, temporal, and seasonal patterns of drought can be better defined, allowing for clearer
identification and modeling of the driving mechanism(s) so that we can more reliably predict what will happen in
the future. Our research strategy uses two approaches to investigate Holocene changes in water availability from a
series of similar lacustrine systems in the Western Cordillera stretching from Colorado to Alaska. Lake-level
changes identified by collection of core transects from shallow to deep water allow us to identify lowstands that are
related to prolonged periods of aridity. This work provides quantitative information on when and how much water
levels have changed, but the temporal resolution is limited to century-scale changes at best. Stable isotope studies of
finely laminated lacustrine carbonates allow for higher resolution studies that can produce water balance information
at subdecadal resolution. Over the last decade we have produced a number of stable isotope records from lake
systems with similar hydrologies in western North America and are at the beginning stages of mapping the spatial
and temporal patterns of Holocene wet/dry cycles. In the last several years we have developed physical models that
allow stable isotope results to be quantified as a means to estimate when, where and how much precipitation has
varied. This requires combining stable isotope results from lakes with open- and closed-basin hydrologies in the
same region to determine how both the isotopic composition and amount of precipitation and evaporation have
changed. Results from nine lake systems spread across the west show remarkably consistent patterns that in some
cases shift in opposite directions at the same time suggesting one region is getting wetter while another is getting
dryer.
A 2000 YEAR RECORD OF PRIMARY PRODUCTIVITY IN THE GULF OF ALASKA USING
CALIBRATED ELEMENTAL PROXY DATA FROM FJORD SEDIMENTS
Jason A. Addisona, Lesleigh Andersonb, John A. Barrona, Bruce P. Finneyc
a
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
US Geological Survey, PO Box 25046, Denver, CO 80225-0046, USA
c
Departments of Biological and Geological Sciences, Idaho State University, Pocatello, ID 83209-8007, USA
b
E-mail address: jaddison@usgs.gov, jbarron@usgs.gov, land@usgs.gov, finney@isu.edu
The climate of the western US is largely controlled by Pacific Ocean-atmosphere dynamics, which manifest through
the position and strength of semi-permanent pressure centers and corresponding storm tracks. As new high-quality
paleoclimate proxy records are developed from terrestrial locations along the Pacific margin of North America, there
is a growing need to develop corresponding high-quality proxy records from coastal marine locations. In many
cases, near-shore marine processes can be directly related to regional climate dynamics, and thus provide
complementary data to test hypotheses developed from terrestrial paleoclimate observations.
We show that variability in biogenic sedimentation from a temperate ice-free fjord in Southeast Alaska
corresponds to regional climate trends in the Gulf of Alaska for the past 100 years. Measurements of sedimentary
Br/Cl ratios using core-scanning XRF methods exhibit temporal variability that tracks well with modern
observations of regional net primary productivity (NPP) during the summer, as well as the Pacific Decadal
Oscillation index (PDO). In Southeast Alaska, positive (negative) PDO phases tend towards intervals of increased
(decreased) marine productivity due to bottom-up forcing by favorable (unfavorable) ocean-atmosphere conditions,
and increased (decreased) delivery of macro- and micronutrients to phytoplankton communities.
We use the modern Br/Cl – NPP covariance to calibrate proxy data for the last 2000 years, and quantify NPP
levels during the earlier Medieval Climate Anomaly (MCA; ~AD 800-1250) and Little Ice Age (LIA; ~AD 1250 –
1900) climate intervals. Relative to 20th Century conditions, we find that: [i] the MCA is expressed as a two-stage
phenomenon; [ii] the early MCA (~AD 800-1000) experienced reduced NPP punctuated by high-magnitude
variability at centennial timescales; [iii] the late MCA (~AD 1000-1250) also experienced high-magnitude
variability but with greater NPP; [iv] the LIA had NPP levels similar to modern conditions with PDO-like decadal
variability; and [v] NPP since AD 1950 has been higher than mean 20th Century conditions, which could be
attributed to a marine ecosystem response related to recent anthropogenic change.
A SPATIOTEMPORAL NETWORK OF ISOTOPES IN ROCKY MOUNTAIN SNOWPACK
Lesleigh Andersona, Max Berkelhammerb, Paco van Sistinea, Alisa Mastc, George Ingersollc, David Clowc
a
US Geological Survey, PO Box 25046, DFC, Denver, CO 80212, USA
CIRES/ATOC, University of Colorado, Boulder, CO 80309, USA
c
US Geological Survey, Colorado Water Science Center, Denver, CO 80225, USA
b
E-mail address: land@usgs.gov, Max.Berkelhammer@colorado.edu
To monitor and evaluate long-term trends in atmospheric deposition and its effects on sensitive alpine ecosystems,
the USGS maintains the Rocky Mountain Regional Snowpack Monitoring Study (Ingersoll et al., 2001). Since 1993,
for >45 sites per year, snowpack depth is recorded in late March, and the complete snowpack column is collected,
melted, integrated, and measured for snow water equivalence (SWE) and chemical constituents such as major ions,
pH, conductance, DOC, and mercury. Since the inception of the network, an aliquot of the water has been archived
for future isotopic analysis. Although resources existed to carry out the isotopic analyses of the earliest samples, it
has only been since recent breakthroughs in the use of laser absorption spectrometry that these measurements can be
done for the remaining samples quickly and inexpensively and with equal analytical quality as with mass
spectrometry. These analyses will comprise the most extensive spatial and temporal effort to document snowpack
isotopic values ever conducted beyond Polar Regions. The data will have wide application, ranging from
investigations of snowpack evolution, ecohydrologic processes, and hydroclimatology. It will also be critical to
improving the interpretation of a number of isotope-based climate proxies in the western US, including lake
sediment calcite (Anderson, 2012), cellulose, leaf waxes and speleothems.
We envision a wide variety of studies and applications at numerous time and space scales beginning with the
development of annual spatiotemporal maps of snowpack isotopes for major Rocky Mountain catchments in ARC
GIS formats. For instance, we can investigate relationships between isotopes in winter season precipitation and
corresponding synoptic climatology by utilizing co-located SNOTEL climate data, climate re-analyses products and
isotope enabled circulation models (Berkelhammer et al., 2011). To better understand the evolution of the snowpack,
we are obtaining a sub-set of co-located weekly precipitation samples from the National Atmospheric Deposition
Program (NADP) network. To better understand the timing of tree water uptake we are obtaining corresponding
isotopes of tree-cellulose that will further develop alternative isotopic approaches to hydroclimatic reconstructions
from tree ring widths (Berkelhammer and Stott, 2012).
Anderson, L., 2012. Rocky Mountain Hydroclimate: Holocene variability and the role of insolation, ENSO, and the
North American Monsoon. Global and Planetary Change 92-93, 198-208.
Berkelhammer, M., Stott, L.D., 2012. Secular temperature trends for the southern Rocky Mountains over the last
five centuries. Geophysical Research Letters doi:10.1029/2012GL052447.
Berkelhammer, M., Stott, L., Yoshimura K., Johnson, K., Sinha, A. 2011. Synoptic and mesoscale controls on the
isotopic composition of precipitation in the western United States. Climate Dynamics doi 10.1007/s0038201101262-3.
Ingersoll, G., Turk, J.T., Mast, A.M., Clow, D.W., Campbell, D.J., Bailey, Z.C. 2001. Rocky Mountain Snowpack
Chemistry Network: History, methods, and the importance of monitoring Mountain Ecosystesm. USGS Open File
Report 01-466. http://co.water.usgs.gov/projects/CO53100/index.html
POLLEN, NPP AND CHARCOAL RECORD LATE-HOLOCENE AND HISTORICAL CHANGE AT A
COASTAL POND, SANTA BARBARA COUNTY, CALIFORNIA
R. Scott Andersona, Ana Ejarquea, Johnathan Ricea, Clayton Lebowb
a
School of Earth Sciences and Environmental Sustainability, and Bilby Research Center, Northern Arizona
University, Flagstaff, AZ 86011, USA
b
Applied Earthworks, Inc., 515 E. Ocean Avenue, Lompoc, CA 93436, USA
E-mail address: Scott.Anderson@nau.edu, Ana.Ejarque@nau.edu, jar373@nau.edu,
clebow@appliedearthworks.com
Mod Pond is a small perennial wetland found within the sage scrub chaparral on Vandenberg Air Force Base. The
pond is 400 m by 120 m and 2 m deep, and sits on the edge of a dune field, at 21 m asl and ca. 3.5 km from the
Pacific Ocean. Sedimentary analysis of pollen, non-pollen palynomorphs (NPPs), and charcoal record environmental
change over the last ca. 2800 years. This record provides not only an opportunity to document the late Holocene
history of vegetation of the region but also to compare the historical record of regional settlement with the
sedimentary proxies. The pollen record suggests that vegetation has remained as sage scrub over most of the last
2800 years, but early on evidence of chaparral, oak grassland, and perhaps even pine woodland is also found.
Abundant charcoal suggests that fires regularly burned around the pond during the late Holocene. Minor changes in
the proxies record the Medieval Climatic Anomaly (MCA; elevated charcoal, plant and algal indicators of lowered
water levels) – Little Ice Age (LIA; lowered charcoal, increased aquatics) climatic fluctuations. Notes from both the
1769 Gaspar de Portolá and the 1776 Juan Bautista de Anza expeditions suggest these explorers knew of this pond
and perhaps camped there. The pond is also shown on several maps dating 1830s-1840s, and the vegetation is
mapped as “chamisal”. Evidence of European-American local impact begins with the first Spanish expeditions in the
1770s and early settlements in Santa Barbaraat the 1780s. Indicators of grazing begin at this time, with the
establishment of exotic herbs, such as Erodium and Brassicaceae, and the deposition of coprophilous fungi such as
Sporormiella-t. Sordaria, and Cercophora-t. Such local grazing impact would imply higher organic matter input into
the lake, as indicated by the increase of zooplankton (Rotifera resting eggs). Contemporary to this, local burning by
the Chumash, which was noted in the Santa Barbara region by the first explorers at ca. 1770, is evidenced from the
charcoal record. Following this, a decline in charcoal deposition in the pond is evidenced as a result of a
proclamation in 1793 by the local Mission forbidding Native American burning. The local planting of Eucalyptus
trees in Santa Barbara about 1870 and early cropping activities are also registered in the pollen record. Aquatic plant
remains document changes in the lake community during the historic period as well. Our study represents one of the
initial comprehensive use of NPPs as an additional proxy to record paleoenvironmental change and human land-use
in California.
COSMOGENIC 10BE DEPTH-PROFILE CHRONOLOGY OF LATE PLEISTOCENE ALLUVIAL FAN
DEPOSITS, BAJA CALIFORNIA, MEXICO
Jose Luis Antinaoa, Eric Mcdonalda, John C. Gosseb, Susan Zimmermannc
a
Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV 89512, USA
Dalhousie University, Halifax, NS B3H 4J1, Canada
c
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore CA 94550, USA
b
E-mail address: jantinao@dri.edu
Late Pleistocene and Holocene alluvial fans in the southern tip of the semiarid Baja California peninsula in Mexico
are characterized by thick sedimentary sequences that display a well-developed soil chronosequence, suggesting
discrete sediment pulses. The high energy depositional environment of these alluvial sediments is evidenced by
sedimentological features like horizontal upper-flow regime bedding, antidunes, and transverse gravel bars. These
features preclude developing an absolute chronology by means of 14C dating of organic remains. We used 10Be
depth-profile cosmogenic nuclide chronology to assess abandonment of two major alluvial fan surfaces near La Paz,
Baja California Sur. Preliminary results yield 10Be depth-profile ages of 67,000+27,000-19,000 years (2-sigma) and
36,000 ± 6000 years (1-sigma) that are out of phase with global glacial variability, but in phase with tropical Pacific
climate variability, and particularly with modeled positive anomalies of the NINO3 index. The study area is
currently subjected to high intensity and long duration precipitation from tropical sources that have been observed to
correlate with ENSO variability. Cosmogenic 10Be inheritance values calculatedfor both depth-profiles are lower by
at least a factor of two compared to values observed in the Mojave and northern Sonoran deserts. Our results
indicate that in this region seasonal high intensity precipitation coupled to rapid weathering of bedrock is generating
cyclic alluvial fan aggradation in response to millennial-scale shifts in tropical climate parameters. Preliminary
results of sedimentological analyses also suggest that the expression of tropical variability is in the form of more
recurrent approach and landfall of tropical cyclones, which perform most of the sediment transport. Ongoing dating
of two younger, extensive fan units in the same area should provide additional constraints on the observed relation to
tropical variability.
COMPARISON OF HIGH-RESOLUTION CLIMATE CHANGE IN TWO SANTA BARBARA BASIN
TIME SERIES (AD 1750-2007 VS. AD 800-1600) BASED ON DIATOMS AND SILICOFLAGELLATES
John A. Barrona, David Bukrya, Ingrid Hendyb, Linda Heusserc
a
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA
c
LDEO, Columbia University, Palisades, NY 10964, USA
b
E-mail address: jbarron@usgs.gov; dbukry@usgs.gov, ihendy@umich.edu, heusser@ldeo.columbia.edu
Diatom and silicoflagellate assemblage changes document the Medieval Climate Anomaly (MCA) and Little Ice
Age (LIA) interval from ~AD 800-1600 in a high-resolution time series in varved sediment recovered in Kasten core
SPR0901-02KC (34°16.845N, 120°02.332W, water depth 588 m) from the Santa Barbara Basin (SBB). When
compared with assemblage changes recorded at two year intervals between AD 1750 and 2007 in the varved
sediments of SBB box core SBBC0806 (Barron et al., in press), these data suggest that SBB surface water
conditions between ~AD 800 and 1600 were mostly within one standard deviation of mean AD 1750-1900
conditions. No clear differences between the MCA and early LIA are recorded by either diatoms or silicoflagellates.
Proxy data for both diatom and silicoflagellate upwelling (exceeding one standard deviation above mean values for
AD 1750-1900) coincide closely with intervals of extreme droughts identified by terrigenous proxy scanning XRF
analyses, supporting the hypothesis that droughts in southern California coincided with cooler (or La Niña-like)
SSTs. Intervals of increased siliciclastic flux are marked by increased percentages of diatoms transported downslope
from the shelf, and these intervals also appear to coincide with deeper thermocline conditions. Diatoms identify only
two intervals of the MCA (at ~AD 880-910 and ~AD 1140-1150) when proxy SSTs exceed one standard deviation
above mean values for AD 1750 and 1900. Conversely, silicoflagellate proxies imply extreme warm water events
only at ~AD 830-860 (early MCA) and ~AD 1360-1370 (early LIA) that are not supported by diatom data. The postAD 1940’s warming of SBB surface waters documented by us in our PACLIM 2011 study (Barron et al., in press)
stands out as the most remarkable event documented in either time series (AD 800-1600 and AD 1750-2007).
Barron, J.A., Bukry, D., and Field, D.B., in press. Response of diatoms and silicoflagellates to climate change in the
Santa Barbara Basin during the past 250 years and the rise of the toxic diatom Pseudo-nitzschia australis. In Starratt,
S.W., ed., Proceedings of the 25th Pacific Climate Workshop, Quaternary International,
doi.org/10.1016/j.quaint.2012.07.02.
A MULTI-PROXY RECONSTRUCTION OF MID TO LATE HOLOCENE PALEOENVIRONMENTAL
CHANGE FROM THE CUENCA ORIENTAL IN MEXICO’S TRANS-MEXICAN VOLCANIC BELT
Tripti Bhattacharyaa, Roger Byrnea, Harald Bohnelb, Kurt Wogaub
a
Department of Geography, University of California, Berkeley, CA 94720, USA
Centro de Geosciencias, Universidad NacionalAutónoma de México (UNAM) Campus Juriquilla, Queretaro
76230, Mexico
b
E-mail address: tripti@berkeley.edu
Central Mexico has a monsoonal climate, with the heating of the land surface encouraging moisture convergence
and convection in the boreal summer. Current inter-annual variability is strongly linked to ENSO, although some
evidence suggests a role for lower-frequency modes like the Pacific Decadal Oscillation. Understanding this lowfrequency variability as well as long-term change in Mexican climate requires detailed paleoclimatic
reconstructions. Unfortunately, a detailed understanding of high-resolution Quaternary climate change in central
Mexico is hindered by a lack of high-resolution, well-dated records, especially from the eastern Trans-Mexican
Volcanic Belt. We present a record from Aljojuca, a maar lake in the state of Puebla in the eastern Trans-Mexican
Volcanic Belt. A 12-m laminated core from Aljojuca, recovered in 2007, has a basal date of approximately 6200 cal
yr BP. We developed a chronology for this core using plant macrofossils and pine pollen concentrations for
radiocarbon dating. The laminated sediments permit a high-resolution reconstruction of past shifts of rainfall and
vegetation, and potentially provide insight into prehistoric anthropogenic land use. Our multiproxy reconstruction
includes pollen, loss- on-ignition, magnetic susceptibility and sediment chemistry (x-ray diffraction and x-ray
fluorescence). Preliminary results suggest that evidence for any anthropogenic impact is largely confined to the
historical period following the Spanish conquest, in contrast to many other sites in highland Mexico. Long-term
climatic fluctuations may be linked to precession-driven changes in the seasonality of insolation, as well as,
millennial-scale variability in ENSO.
SUPPLEMENTING A TULARE LAKE, CALIFORNIA LATE PLEISTOCENE AND HOLOCENE LAKELEVEL RECORD USING GEOCHEMICAL AND GEOPHYSICAL PROXIES FROM CORE
SEDIMENTS; CONTINUING WORK
Ashleigh B. Blunt, Robert M. Negrini, Kathleen Randall, Kelsey Padilla, Logan Prosser, James Wilson, Emmanuel
Garcia, Stephanie Unruh Caffee
Department of Geological Sciences, California State University, Bakersfield, Bakersfield, CA 93311, USA
E-mail address: rnegrini@csub.edu
Geochemical and geophysical proxies from Tulare Lake cores in the San Joaquin Valley of California are shown to
reliably reflect lake-level changes and extend the record back to 18,000 cal yr BP. Previous outcrop and trenchbased mapping studies indicated several high- and low-stand events throughout the Holocene, events that have
proven to be consistent with other lake records from the southwestern coastal US. Our record employs
carbon/nitrogen (C/N), total inorganic carbon (TIC), grain size, and magnetic susceptibility proxies sampled at 1-cm
intervals to provide a significantly higher resolution record than previous work. These proxies systematically vary as
predicted with previously suggested lake level changes. An earlier phase of the study demonstrated that the proxies
are consistent with previous outcrop and trench based studies as indicated by the transition from deep lake to marsh
conditions centered at 3000 cal yr BP, which was associated with a drop of C/N ratio from 40 to 5, and an increase
in TIC% from 0% to 2%. Further studies infer two several hundred-year-long lowstand events centered at 9700 cal
yr BP and 7800 cal yr BP which are associated with an increase in TIC from 0% to 1.4-2.0%. The former lowstand
event corresponds with a beach sand deposit described in a previous outcrop study (Negrini et al., 2006) and high
concentration of littoral pollen from the previous depocenter core study by Davis (1999). The latter lowstand
corresponds to a coarsening-upward sand in a marsh deposit described by Negrini et al. (2006) as well as a low C/N
ratio from Lower Bear Lake, California and low sand percent from Lake Elsinore, California at the same time as
discussed by Kirby et al. (2012). Our results indicate that core-based proxies can be used to supplement outcrop and
trench-based studies to collectively form an accurate and nearly continuous record of Tulare Lake levels for the past
18,000 years. Since historic and reconstructed lake-level histories indicate that the surface elevation of Tulare Lake
is primarily controlled by Sierra Nevada stream runoff, our comprehensive lake-level history will be integral in
forecasting changes in southern San Joaquin Valley water supply due to anticipated climate change.
Davis, O.K., 1999. Pollen analysis of Tulare Lake, California: Great Basin-like vegetation in Central California
during the full-glacial and early Holocene. Review of Palaeobotany and Palynology 107, 249-257.
Kirby, M.E., Zimmerman, S.R.H., Patterson, W.P., Rivera, J.J., 2012. A 9170-year record of decadal-tomulti-centennial scale pluvial episodes from the coastal Southwest United States: a role for atmospheric rivers?
Quaternary Science Reviews 46, 57-65.
Negrini, R.M., Wigand, P.E., Drauker, S., Gobalet, K., Gardner, J.K., Sutton, M.Q., Yohe II, R.M., 2006. The
Rambla highstand shoreline and the Holocene lake-level history of Tulare, Lake, California, USA. Quaternary
Science Reviews 25, 1599-1618.
USING SEDIMENTARY RECORDS TO INFORM THE CAUSES OF WOODY PLANT
ENCROACHMENT IN SOUTHWESTERN US DESERT GRASSLANDS
Andrea Brunellea, Thomas A. Minckleyb, Jose Delgadilloc
a
Geography Department, University of Utah, Salt Lake City, UT 84112, USA
Geography Department, University of Wyoming, Laramie, WY 82071, USA
c
Universidad Autonoma de Baja California, Ensenada, Mexico
b
E-mail address: andrea.brunelle@geog.utah.edu, minckley@uwyo.edu, jdelga.jose@gmail.com
It has long been recognized that across the desert southwest there has been a relatively recent increase in the
abundance of woody taxa in areas previously dominated by desert grassland. The exact timing of the increase in
woody taxa and the causes for the increase have been debated. The main hypotheses for this increase in woody taxa
include grazing pressure, fire exclusion, climate, and higher carbon dioxide concentrations. Pollen and charcoal data
from desert ciénegas along with other time series demonstrate that increases in woody taxa over the last 150 years
are unprecedented for the last 5500 years and that they are correlated mainly to intense late 19th century grazing and
human induced increases in carbon dioxide. Fire activity (as represented by charcoal abundance) actually increases
along with woody taxa abundance and so suggests that fire exclusion was not a factor. Climate phenomena such as
drought and the variability associated with the El Niño-Southern Oscillation also do not appear to correlate with the
changes in abundance of woody taxa.
MAKAUWAHI CAVE, KAUA`I: PALEOECOLOGY SPAWNS NEW IDEAS IN CONSERVATION
David A. Burney
National Tropical Botanical Garden, 3530 Papalina Road, Kalaheo, HI 96741, USA
E-mail address: dburney@ntbg.org
A cave and sinkhole system in eolian calcarenite on the south shore of Kaua`i has proved over more than two
decades of excavation and multidisciplinary paleoecological research to be a remarkable archive of insular biotic
and abiotic processes. Spanning 10 millennia or more, the record of plant and animal fossils, including microfossils
and ancient DNA, tells the story of Hawai`i before humans in unprecedented detail. The uppermost millennium of
sediments documents the full story from human arrival to Polynesian population growth, to European contact,
Plantation-era changes, and the present era. Over 10 m of soft sediments have been studied by an interdisciplinary
group that includes palynologists, avian paleontologists, archaeologists, speleologists, sedimentologists, and
invertebrate paleontologists. Makauwahi Cave provides full documentation of a spectacular lost world, and how it
was lost. Giant flightless ducks and geese were the shapers of the vegetative landscape, and top carnivores were big
diurnal owls that caught other birds on the wing. These coastal lowlands hosted a diversity of plants and animals to
rival any of Hawai`i’s surviving montane ecosystems. About a decade ago, my wife Lida Pigott Burney and I leased
the property in order to test some new ideas in conservation that had been spawned by these paleoecological
insights. Using the site’s splendid fossil record of late Holocene prehuman environments as a guide, we set out to
transform the surrounding landscape, consisting of abandoned farmland and piles of mine spoil, into an ecosystem
as it might have appeared to the earliest Hawaiian colonists. Today the Makauwahi Cave Reserve, a communitybased nonprofit under Garden Island Resource Conservation and Development, in cooperation with landowner
Grove Farm Company, hosts university-accredited field schools and internships, produces millions of native plant
seeds and plants for government and private restorations, and conducts large-scale experiments in applied ecology.
Some of these ideas have helped spawn a new hybrid subdiscipline, Conservation Paleobiology and forged linkages
with projects and sites as far away as Madagascar, Siberia, and Ted Turner’s western mega-ranches. I describe this
odyssey more fully in Burney (2010).
Burney, D.A., 2010. Back to the Future in the Caves of Kaua`i: A Scientist’s Adventures in the Dark. Yale
University Press, 216 p.
HOLOCENE VARIABILITY OF A CLIMATIC BOUNDARY IN THE INTERMOUNTAIN WEST
Vachel A. Cartera, Andrea Brunellea, Tom A. Minckleyb, Phil Dennisona
a
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
Department of Geography, University of Wyoming, Laramie, WY 82071, USA
b
E-mail address: vachel.carter@gmail.com
In the Intermountain West, a climatic boundary between 40o and 45o north latitude separates the northern and
southern Rocky Mountains. It is unclear whether fire regimes within this boundary are associated with the northern
or southern Rocky Mountains. Long Lake, Wyoming, is located in the Medicine Bow Range within this climatic
boundary, making it an ideal study location to assess the similarity to northern and southern regional fire regimes.
High-resolution paleoecological data are used to explore whether the fire regime at Long Lake was more similar to
sites in the northern or southern Rocky Mountains throughout the Holocene. During the early Holocene (11,8009400 cal yr BP) fire frequency and peak magnitude increased, but no regional similarities were evident at Long
Lake. During the middle Holocene (9400-4000 cal yr BP) fire return intervals were the longest of the record and
peak magnitudes had the greatest variability. Fire activity was similar to the southern Rocky Mountain sites and
northern Rocky Mountain sites south of 44oN. An anomalous Populus-dominated period (4000-3100 cal yr BP) is
accompanied by frequent fire episodes and high peak magnitudes. Fire activity was similar to the sites from the
northern Rocky Mountains. During the late Holocene (3100 cal yr BP-present) fire activity increased but peak
magnitudes decreased. It was most similar to the southern Rocky Mountains and northern Rocky Mountain sites
south of 45oN. These results suggest the fire regime in this climatic boundary have a greater affinity with the
southern Rocky Mountains. Future climate change is likely to affect this boundary and accompanying fire regimes.
Understanding the influence of climatic boundaries on local and regional fire regimes will aid in conservation and
management strategies in the 21st century.
A ~14,500 YEAR FIRE AND SEDIMENT HISTORY OF A DESERT WETLAND IN NEW MEXICO
Vanessa Chavez, Andrea Brunelle
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
E-mail address: vanessa.chavez@utah.edu
Sediment samples from the archeological site at Boca Negra Wash, New Mexico were examined in order to
construct a prehistoric fire history for the area. A ~14,500 year fire record was reconstructed from sediments
collected from trench 2 of this site using charcoal data and magnetic susceptibility. Radiocarbon dates and depths
from a stratigraphic cross section in (Holliday et al. 2006) were used to construct an age model and lithostratigraphic
column for this site. The magnetic susceptibility of sediment samples from this trench showed higher values in
sandy layers, particularly where an unconformity was identified. This observation is consistent with the higher
magnetic readings associated with coarser grained, terrestrial deposits and serves as an indicator of aeolian activity
and potentially high surface erosion. Results from the fire reconstruction show that fire activity is insignificant until
~6900 years BP. This observation is largely consistent with data from multiple sites and is concurrent with the onset
of the El Niño Southern Oscillation (ENSO), suggesting that ENSO plays some part in controlling fire occurrence in
desert wetlands (Brunelle et al., 2010). Information from Boca Negra Wash offers further insight in to understanding
the relationship between fire and climate in desert environments and how these regimes may evolve with future
climate change.
Brunelle, A., Minckley, T.A., Blissett, S., Cobabe, S.K., Guzman, B.L., 2010. A ~8000 year fire history from an
Arizona/Sonora borderland ciénega. Journal of Arid Environments 74, 475-481.
Holliday, V., Huckell, B., Mayer, J.H., Forman, S.L., McFadden, L.D., 2006. Geoarcheology of the Boca Negra
Wash area, Albuquerque basin, New Mexico, USA. Geoarcheology 21, 765-802.
A ~50,000 YEAR RECORD OF VEGETATION CHANGE AND FIRE IN CENTRAL COASTAL
CALIFORNIA
Alicia Cowarta, Roger Byrnea, Rob Cuthrellb, Matthew Kirbyc
a
Department of Geography, University of California, Berkeley, CA 94720, USA
Department of Anthropology, University of California, Berkeley, CA, 94720 USA
c
Department of Geological Sciences, California State University, Fullerton, CA 92834, USA
b
E-mail address: alicia@berkeley.edu
There are few terrestrial records of long-term vegetation change in central coastal California because most lakes in
the area are less than 5000 years old. Here we report on analyses of an eight meter sediment core from Laguna de las
Trancas, a landslide-dammed pond near Año Nuevo State Park with a basal date of ~50,000 cal yr BP. The age
model for the core is based on approximately twenty AMS radiocarbon dates. Methods include the analyses of
pollen, microscopic charcoal, loss-on-ignition, and sediment grain size. Preliminary results show that prior to
~40,000 cal yr BP, Pinus and TCT pollen are important. At ~20,000 cal yr BP, members of the Poaceae and
Asteraceae families become the dominant taxa. Abies pollen makes an appearance after ~20,000 cal yr BP and then
declines around the time that Sequoia pollen becomes dominant at ~8,000 cal yr BP. Sequoia, Poaceae, and other
weedy taxa continue to comprise a significant portion of the pollen rain until the present. Charcoal is abundant only
in the top 200 cm of the core, indicating that fires were infrequent in the Pleistocene but increased dramatically
during the Holocene.
PALEOECOLOGY OF GRAND STAIRCASE-ESCALANTE NATIONAL MONUMENT, UTAH: HUMAN
IMPACTS ON LANDSCAPE AND IMPLICATIONS FOR RESOURCE MANAGEMENT ON THE
SOUTHERN COLORADO PLATEAU
Robert M. D’Andreaa, R. Scott Andersona, Kenneth L. Coleb, Matthew K. Zweifelc
a
School of Earth Sciences and Environmental Sustainability, Environmental Sciences and Policy Program, Northern
Arizona University, Flagstaff, AZ 86001, USA
b
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86001, USA
c
Bureau of Land Management, Grand Staircase-Escalante National Monument, Kanab, UT 84741, USA
E-mail address: rmd233@nau.edu, scott.anderson@nau.edu, ken.cole@nau.edu
Utah’s Grand Staircase-Escalante National Monument (GSENM) encompasses 1.7 million acres of southern Utah’s
Kane and Garfield counties and the Bureau of Land Management (BLM) is responsible for managing the region’s
vast biological, cultural, and geological resources. Reconstructions of Holocene vegetation, fire, and climate
histories provide BLM managers with baselines for local ecological restoration and fire management strategies,
however, paleoecological records within the Monument are scarce. In addition, knowledge of archaeological site
function is instrumental in influencing cultural resource management decisions, however, the monument’s unique
assemblage of archaeological site types are often characterized by ambiguous land use histories. An investigation of
pollen, non-pollen palynomorphs (NPPs), macrofossils, and charcoal recovered from Lake Pasture and Canyon
Meadow sediment cores and packrat middens will determine vegetation changes and fire regimes for two distinct
physiographic regions of the monument, the Kaiparowits Plateau and the Grand Staircase, respectively, and
determine ecosystem disturbance associated with indigenous as well as Euro-American land use practices. Virgin
Branch Anasazi-type site architecture and artifacts found near the lakes suggest that they may have been centers for
agricultural activity and investigations of pollen from lake sediments and packrat middens may determine when
agricultural species were introduced to the region as well as the plant species being cultivated through time. The
combination of lake sediment core and packrat midden analysis from the same site is a novel and powerful approach
toward paleoecological reconstruction as both local and regional vegetation can be represented, reducing
depositional biases. In addition, the ability to crosscheck paleoecological data with archaeological records for each
site will lead to more definitive interpretations of human land use and its resulting effects on the landscape. In
addition to informing cultural and natural resource management decisions within the GSENM, this study will also be
helpful for federal and state level land management agencies on the greater southern Colorado Plateau.
PROJECTIONS OF FUTURE ATMOSPHERIC RIVERS ON THE WEST COAST OF NORTH AMERICA
Michael D. Dettingera, F. Martin Ralphb
a
US Geological Survey, Scripps Institution of Oceanography, La Jolla, CA 92093, USA
NOAA/PSD/Earth Systems Research Laboratory, Boulder, CO 80305 , USA
b
E-mail address: mddettin@usgs.gov, marty.ralph@noaa.gov
Recent studies have documented the important role that ‘‘atmospheric rivers’’ (ARs) of concentrated water vapor
about 1-2 km above the Pacific Ocean play in the storms and floods in California, Oregon, and Washington (as well
as somewhat less often in the interior West). By delivering large masses of warm, moist air (sometimes directly
from the Tropics), ARs establish conditions for the kinds of high snowlines and copious orographic rainfall that
have caused the largest historical storms. In many California rivers, 80% or more of all major historical floods have
been associated with AR storms. We also currently hypothesize that the very large floods in California’s preinstrumental past were associated with ARs. The occurrence of such storms in historical observations and in a new
multi-model ensemble of IPCC 5th Assessment climate simulations is being evaluated. In an earlier evaluation of
projections from the previous (4th) IPCC Assessment, average AR numbers and intensities offshore from central
California increased by about 10-15%; however, years with many AR episodes, ARs with higher-than-historical
water-vapor transport rates, and AR storm-temperatures all increased. Now, the statistics of numbers of ARs per
year, AR intensities and AR temperatures are being revisited in the more complete multi-model ensemble of
climate-change projections from the IPCC 5th Assessments at points all along the West Coast, along with durations
of AR passage over each coastal point, times between AR arrivals, the vertical displacements of air packages within
ARs needed to reach saturation with respect to water, and the atmospheric stability of the AR profiles. This new
evaluation will be an update to the previous study and has been designed as input specifically for California’s
Central Valley Flood Protection Plan program.
WEST COAST ENVIRONMENTAL CHANGE OVER THE LAST 150,000 YEARS: A CASE STUDY FROM
BALDWIN LAKE, SAN BERNARDINO MOUNTAINS, CALIFORNIA
Katherine Glovera, Glen MacDonalda, Matthew Kirbyb
a
b
Department of Geography, UCLA, Los Angeles, CA 90095, USA
Department of Geological Sciences, California State University, Fullerton, CA 92834, USA
E-mail address: kcglover@ucla.edu, mkirby@fullerton.edu
Marine cores and large lake basins have great potential to preserve a history of the hydrology and ecology of their
watershed area. Currently, there are few terrestrial records in southern California that extend back to MIS 5e
(~130,000–115,000 years ago), an interglacial analogous to the Holocene in terms of both its temperature and
stability. Baldwin Lake, in San Bernardino County, is a recently-studied lake that could help fill this gap in our
understanding of West Coast paleoclimate. Prior work on a 14 m section from the lake depocenter (Kirby et al.,
2006; Blazevic et al., 2009) demonstrated synchronicity with Santa Barbara Basin and Greenland records. Extraction
of a longer (26 m) core took place during August 2012 fieldwork, and the recovered material demonstrates clear
inorganic-organic cycles in its downsection lithology. Proxy analyses will ultimately include magnetic
susceptibility, loss-on-ignition, grain size, charcoal content, and palynology, and provide insight into southern
California’s paleoecology and past hydrologic variability.
Kirby, M.E., Lund, S.P., Bird, B.W., 2006. Mid-Wisconsin sediment record from Baldwin Lake reveals
hemispheric climate dynamics (southern CA, USA). Palaeogeography, Palaeoclimatology, Palaeoecology 241, 267–
283.
Blazevic, M.A., Kirby, M.E., Woods, A.D., Browne, B.L., Bowman, D.D., 2009. A sedimentary facies model for
glacial-age sediments in Baldwin Lake, Southern California: Sedimentary Geology 219(1-4), 151-168.
MULTI-PROXY CHARACTERIZATION OF ABRUPTLY DEPOSITED SEDIMENTARY PACKAGES
AT PETALUMA MARSH, SONOMA COUNTY, CALIFORNIA
Michelle Gomana, B. Lynn Ingramb, Frances Malamud-Roamc, Kirsten Helgesonb, Nicholas Darsta, Ashley Stewarda
a
Department of Geography and Global Studies, Sonoma State University, Rohnert Park, CA 94928, USA
Department of Earth and Planetary Science, and Geography University of California Berkeley, CA 94720, USA
c
CalTrans, 111 Grand Avenue, Oakland, CA 94612, USA
b
E-mail address: goman@sonoma.edu, ingram@eps.berkeley.edu, fmalamudroam@gmail.com
Petaluma Marsh, at ~20km2, is the largest remaining extant salt marsh in San Pablo Bay, California. The marsh lies
within the Petaluma River watershed which drains approximately 380 km2 of land in southern Sonoma county and
portions of the northeastern Marin county. The marsh formation and continued development is connected to the
fluvial system as well as sea level. Sediment cores retrieved from the marsh therefore have the potential to reveal
long-term trends in climate change, as well as, extreme weather events.
We present preliminary data from several cores retrieved from Petaluma Marsh. The cores were collected
approximately 700 m due south of the Petaluma River. Tule tidal slough is approximately 100 m away from the core
site. The dominant vegetation at the site is pickleweed (Sarcocornia pacifica) with dodder (Cuscutasalina sp.) and
gum plant (Grindelia stricta) at higher elevations.
To date, sedimentary and biological proxy analysis has focused primarily on core 1a. This core shows classic
sedimentary facies changes reflecting the progression of marsh formation from mud flat to incipient marsh to fully
developed peat marsh. However, on two occasions fully developed marsh peat is abruptly overlain by thick
packages of inorganic muds. The abrupt change in stratigraphy suggests a dynamic sedimentary event affected the
marsh. In this poster we present preliminary multi-proxy data selected to characterize these sedimentary packages
and shed light on their cause. Our current working hypothesis is that these packages are the result of intense flooding
events most likely caused by an Atmospheric River event.
EFFECTS OF HYDROLOGIC EVENT HISTORY ON THE SUSPENDED-SEDIMENT BEHAVIOR OF A
CENTRAL CALIFORNIA RIVER
Andrew B. Graya, Jonathan A. Warrickb, Elizabeth B. Watsonc, Gregory B. Pasternacka
a
Department of Land, Air and Water Resources, University of California Davis, Davis, CA 95616, USA
US Geological Survey Pacific Coastal and Marine Science Center, Santa Cruz, CA 95060, USA
c
US Environmental Protection Agency Atlantic Ecology Division, Narragansett, RI 02882, USA
b
E-mail address: abgray@gmail.com, jwarrick@usgs.gov, Watson.Elizabeth@epamail.epa.gov
Suspended-sediment yields of many developed watersheds have decreased with time, and increased urbanization
and hydrologic modifications are often identified as contributing mechanisms. Examination of a river system that
had not experienced these alterations during the period of record, yet displayed high variability in suspendedsediment behavior and decreasing trends in sediment yield provided an opportunity to evaluate the effects of
hydrologic event history. The objectives of this study were to identify the time-dependent behavior of suspendedsediment concentrations at the terminus of the Salinas River, California, since the initiation of monitoring in the late
1960’s, and determine the hydrologic factors that influenced this behavior. The Salinas River is a seasonally active
river of moderate size that may be particularly susceptible to the effects of hydrologic event history on suspended
sediment behavior due to the high variability of discharge in this system, which is largely driven by ENSOinfluenced storm events. We found that suspended sediment yield from the Salinas had decreased, despite little
change in the proportion of urbanized land area and no major dam emplacement during the period of record.
Hydrologic factors, including hydrograph slope, change in daily discharge and elapsed time since the last high
discharge event were found to have significant positive effects on discharge corrected suspended sediment
concentrations. The positive effect of hydrograph slope on suspended sediment concentration implied that fine
suspended sediment in the lower Salinas displayed a generally positive hysteretic behavior, which was supported by
the prevalence of positive hysteresis in events with sufficient data density for analysis. Identification of the
preferential mobilization of sediment on the rising limb of the hydrograph as the major mechanism for the overall
hysteretic pattern is forensically supported by the annual occurrence of in-channel suspended sediment deposition by
early season, channel terminating flows and the flushing function of major hydrologic events found in this study.
While hydrologic characteristics were not responsible for temporal changes in suspended sediment behavior, future
changes in ENSO cycling would alter the periodization of larger, channel sediment flushing events, in turn affecting
suspended sediment residence time in the channelized system.
RESOLVING VARVE AND RADIOCARBON CHRONOLOGY DIFFERENCES IN THE SANTA
BARBARA BASIN SEDIMENTARY RECORD, CALIFORNIA
Ingrid L. Hendya, Larianna Dunna, Arndt Schimmelmannb, Dorothy K. Pakc
a
Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI 48109, USA
Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA
c
Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
b
E-mail address: ihendy@umich.edu
Santa Barbara Basin (SBB) is well known for producing high quality paleoclimate reconstructions, but the validity
of correlations between the basin and other regions rests upon age model accuracy. Yet, the two independent and
well-established chronologies based on varve counting and foraminifera-based radiocarbon dating does not
consistently agree during the last two millennia. Here the validity of age model assumption that the regional
reservoir age of surface waters was invariably 641 ±119 years through time is tested. This high-resolution14C study
of SBB sediments compares 49 mixed planktonic foraminiferal carbonate and 20 terrestrial organic carbon 14C dates
to the varve chronology, in order to extend the high-resolution paleoclimate chronology of the basin back ~2000
years. Evidence indicates that regional reservoir ages do not remain constant through time with ΔR, (i.e. regional
reservoir age minus variations in the global mixed-layer ocean reservoir age) fluctuating between 80 and 350 years.
Second, there is a consistent (R2= 0.96) undercounting of laminae couplets (traditionally presumed to represent
varves) between AD 150 and ~AD 1700 based on a new varying ΔR14Cchronology. Previous investigations of SBB
varves have focused on the competing roles of biogenic sediment delivery and bottom water oxygen concentrations
on the generation of laminae couplets. Due to the Mediterranean climate of the SBB region, loss of varves may
occur when low riverine input and infrequent winter storm activity fail to supply siliciclastic layers during La Niña
years and negative Pacific Decadal Oscillations. Here we test the assumption that laminae couplets are annual
independently of previous studies. We compare two 20th century chronologies generated from the major siliciclastic
element concentrations generated by scanning XRF analysis of box core SPR0201-04BC. The first chronology
assumes annual precipitation delivery controls laminae couplets and the second assuming laminae couplets are
controlled by interannual variability. Although differences between the chronologies are small, they demonstrate
how age model assumptions can influence the interpretation of paleoclimatic reconstructions.
THE RETURN OF ATMOSPHERIC RIVERS: TRANSITIONING FROM THE MEDIEVAL CLIMATE
ANOMALY TO THE LITTLE ICE AGE IN SOUTHERN CALIFORNIA
Ingrid L. Hendya, Arndt Schimmelmannb, Dorothy K. Pakc, Linda Heusserd
a
Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI 48109, USA
Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA
c
Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
d
LDEO, Columbia University, New York, NY 10964, USA
b
E-mail address: ihendy@umich.edu
Southern California has a Mediterranean type climate characterized by warm dry summers associated with the
seasonal position of the North Pacific high pressure system and cool, wet winters primarily associated with cyclonic
storms originating in low pressure systems in the high latitude North Pacific. Winter storm activity is reduced during
negative phases of the Pacific Decadal Oscillation (PDO). Extreme precipitation events in the region, however,
occur when strong zonal flow brings warm, moist tropical air across the Pacific (atmospheric rivers), often in
association with El Niño. Here we present an annually resolved reconstruction of riverine input into Santa Barbara
Basin (SBB) during the Medieval Climate Anomaly (MCA) transition into the Little Ice Age (LIA) based on
scanning XRF elemental composition of bulk sediments (AD 800 to 1500). The first Principle Component (PC1) of
the elemental data contains high loadings of Ti, K, Al, Si, Rb, and Fe, and explains 40% of the variance in kasten
core SPR0901-03KC. We associate PC1 with siliciclastic sediment delivered to SBB by river runoff. Therefore, low
PC1 values are interpreted as reduced river runoff as precipitation decreased during droughts. Droughts indicated
bythe elemental composition of SBB sediments were centered at AD 870, 970, 1140, 1300, and 1450. The dry
conditions of the MCA were terminated by flood events at ~AD 1270, 1380 and 1530. Additionally the transition
from the MCA to the LIA was associated with a dramatic increase in the abundance of the subpolar planktonic
foraminiferal species Neoglobogerina pachyderma (sinistral). Although variable, this interval is characterized by a
foraminiferal species preferring water <10°C lasting from ~AD 1250 to 1330 with peak abundances of 42% at ~AD
1260. A brief increase in subtropical planktonic foraminferal species occurred between ~AD 1350 and 1420 before
the foraminiferal assemblage shifted toward cooler subpolar species again at ~AD 1450. Negative PDO has been
suggested for AD 1285-1300 (MacDonald and Case, 2005) while strong El Niño events have been proposed for the
late 13th century (Mann and Jones, 2003). These changes in interannual variability follow three major volcanic
eruptions occurring between AD 1258 and 1270 that are recorded in ice core aerosols and have been linked in
cooling in Europe (Stothers, 2000).
MacDonald, G.M., and Case, R.A., 2005. Variations in the Pacific Decadal Oscillation over the past millennium:
Geophysical Research Letters 32(8).
Mann, M.E., and Jones, P.D., 2003. Global surface temperatures over the past two millennia: Geophysical Research
Letters 30(15).
Stothers, R.B., 2000. Climatic and demographic consequences of the massive volcanic eruption of 1258. Climatic
Change, 45, 361-374.
MULTI-DECADAL VARIATION IN SOUTHERN CALIFORNIA DROUGHT DURING THE MEDIEVAL
CLIMATE ANOMALY AND LITTLE ICE AGE (~AD 800- ~AD 1600): EVIDENCE FROM COEVAL
TERRESTRIAL AND MARINE PROXIES
Linda E. Heussera, Ingrid E. Hendyb, John A. Barronc, Dorothy Pakd
a
Lamont Doherty Earth Observatory of Columbia University, Palisades, NY 10962, USA
Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA
c
US Geological Survey, MS910, Menlo Park, CA 94025, USA
d
Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
b
E-mail address: heusser@ldeo.columbia.edu, ihendy@umich.edu, jbarron@usgs.gov, pak@geol.ucsb.edu
High-resolution studies of precipitation proxies (pollen from coastal, drought-resistant chaparral and upslope mesic
oak-pine woodlands, and bulk sediment Ti%) from sediments deposited in Santa Barbara Basin (SPR0901-02KC;
34°16.845N, 120°02.332W, water depth 588 m) reflect decadal-scale fluctuations in persistent severe drought
spanning from ~ AD 800 to 1270. Pollen from chamise and manzanita chaparrals (sclerophyllous woody shrubs
dominated by Adenostoma and Arctostaphylos) begins to decline at ~AD 1265, while oak-pine woodlands begin to
increase at ~AD 1211 reaching a maximum between ~AD 1500-~1600. Termination of the last major drought in our
record coincides with that of major drought events elsewhere in the West (Stine, 1994; Cook et al., 2004), and marks
the beginning of gradual, fluctuating increases in precipitation and in coastal southern California mesic, oakdominated communities. Offshore, diatom, oxygen isotopes, and planktonic foraminifera data imply cold spring and
warm winter sea surface temperatures during the Medieval Climate Anomaly (MCA) that reverse in the Little Ice
Age (LIA). These major climate-driven changes in southern California and Santa Barbara Basin are consistent with
changes in northern hemisphere circulation, i.e., weakened Arctic lows, strengthened North Pacific highs and
extended La Niña-like conditions during the MCA and strengthened Aleutian lows, weakened and westward North
Pacific highs and extended El Niño-like atmospheric conditions during the LIA.
Cook, E.R., Woodhouse, C.A., Eakin, C.M., Meko, D.M., Stahle, D.W., 2004. Long-term aridity changes in the
western United States. Science, 306(5698), 1015-1018.
Stine, S., 1994. Extreme and persistent drought in California and Patagonia during mediaeval time. Nature 369, 546549.
THE LATE PLEISTOCENE PLUVIAL HISTORY OF SURPRISE VALLEY, CALIFORNIA
Daniel E. Ibarraa, Anne E. Eggerb, Kate Mahera
a
b
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA
Department of Geological Sciences, Central Washington University, Ellensburg, WA 98926, USA
E-mail address: danieli@stanford.edu
Motivated by the potential for dramatic future hydrologic changes, studies that investigate the transitions between
Earth’s different climate states have the potential to enhance our understanding of the modern climate system and
potential future variability. The interval surrounding the Last Glacial Maximum (LGM) represents a period when
Earth’s boundary conditions, greenhouse gas concentrations and orbital parameters were substantially different than
today, and thus reconstruction of climate at the LGM provides a key test for climate models. Our study examines the
performance of the Paleoclimate Model Intercomparison Project 3 (PMIP3) simulations to a lake shoreline record in
an effort to better reconstruct changes in the hydrologic cycle over the western United States during the LGM. To
enhance the spatial coverage of lake level records in the western United States, we investigated the timing and
magnitude of the most recent pluvial lake cycle at Surprise Valley, California, a valley inferred from modern
topography to be isolated during the late Pleistocene. To investigate the paleohydrology of Lake Surprise we
combine 230Th-U and radiocarbon ages with δ18O, δ13C and Sr/Ca measurements of shoreline tufa deposits. This new
lake record, spanning the last glacial cycle,places lake level 180 and 100 m above present day playa, at 13,900 ±
1200 and 22,500 ± 4600 yr BP, respectively. Modeling of isostasy suggests that contributions from crustal flexure
during the late Pleistocene were minor, reaching 11 m at most. Combined isotopic and hydrologic modeling of Lake
Surprise indicates that annual precipitation may have increased by as much as 164% and 24%, relative to modern,
during the lake highstand and the LGM, respectively. We compare our results to PMIP3 climate model simulations
of the LGM (21,000 yr BP). Most PMIP3 models predict varying amounts of increased precipitation during the
LGM for Surprise Valley, with an ensemble average predicting a precipitation increase of 14% relative to modern.
DEGLACIAL HYDROCLIMATES ACROSS THE COASTAL SOUTHWEST UNITED STATES INTO
THE INTERIOR SOUTHWEST UNITED STATES, INCLUDING NORTHWEST MEXICO: TIMING,
PHASING, AND FORCINGS
Matthew E. Kirbya, Sarah J. Feakinsb, Nicole Bonusoa, Joanna M. Fantozzia, Christine A. Hinera
a
b
Department of Geological Sciences, California State University, Fullerton, CA 92834, USA
Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089, USA
E-mail address: mkirby@fullerton.edu, feakins@usc.edu
Understanding the patterns and causes of the last deglaciation offers insights into how climate changes under abrupt
global climate forcings. This abstract focuses on the deglacial hydroclimate of the coastal and interior southwest
United States and northwest Mexico. We include a new record from Lake Elsinore, located 36 km inland from the
Pacific Ocean in southern California. This new record contains a continuous, high resolution (multi-decadal scale)
deglacial sequence spanning 19,000 to 9000 yr BP. Sedimentological and geochemical analyses of the Lake Elsinore
sediments reveal dramatic hydrologic variability during the deglacial transition. In particular the sand and total
carbonate fractions indicate a three-step deglacial sequence separated by two abrupt transitions at the Older Dryas
(OD) to Bølling-Allerød (B-A) and B-A to Younger Dryas (YD)-Holocene. Compound specific hydrogen isotope
analyses of the C28 n-alkanoic acid from plant leaf waxes preserved in the Lake Elsinore core add insights into the
moisture source regions. A generally linear increase in δDwax values from 19,000 to 9000 yr BP is interpreted to
reflect a long term change from North Pacific to more sub-tropical moisture sources. Our comparison to sites from
the interior southwest US and northwest Mexico shows similar hydrologic responses during the OD (wet) and the BA (drier) as well as timing of the hydrologic transition. A wetter OD is interpreted to reflect enhanced winter season
precipitation and vice versa for the B-A. The timing of the transition from the B-A to the YD is generally congruent
across the study region. However, the phase of hydrologic changes into the YD (wet vs. dry) is variable. Using the
“modes of deglacial variability” (Clark et al., 2012) as a basis for evaluating forcings of the last deglaciation, we
observe a regionally specific “forcing dipole” separating the coastal southwest from the interior southwest. While
the interior southwest climate regime dominates the region spatially and has been the focus of reconstructions, we
urge greater attention be paid to differentiating responses in the coastal southwest, through additional paleoclimatic
reconstructions and regional climate model experiments.
Clark, P.U., Shakun, J.D., Baker, P.A., Bartlein, P.J., Brewer, S., Brook, E., Carlson, A.E., Cheng, H., Kaufman,
D.S.,Liu, Z., Marchitto, T.M., Mix, A.C., Morrill, C., Otto-Bliesner, B.L., Pahnke, K., Russell, J.M., Whitlock, C.,
Adkins, J.F., Blois, J.L., Clark, J., Colman,S.M., Curry, W.B., Flower, B.P., He, F., Johnson, T.C., Lynch-Stieglitz,
J., Markgraf, V., McManus, J., Mitrovica, J.X., Moreno, P.I., Williams, J.W., 2012. Global climate evolution during
the last deglaciation. Proceedings of the National Academy of Sciences 109(19), E1134–E1142.
SALMON ABUNDANCE IN THE OREGON COAST: A 5400-YEAR PALEOLIMNOLOGICAL
RECONSTRUCTION
Jennifer E. Kuslera, Daniel Gavinb
a
US Geological Survey, 345 Middlefield RoadMenlo Park, CA 94025, USA
Department of Geography, University of Oregon, Eugene, OR 97403, USA
b
Email address: jkusler@usgs.gov
The abundance of Pacific salmon (Oncorhynchus spp.) has decreased notably in historical times. Though many
anthropogenic stressors have been identified, little is known about the natural variability or long-term history of
salmon populations in the Oregon Coast Range. In this study, a 5400-year record of coho salmon abundance was
developed by analyzing numerous proxies from lake sediment cores. Proxies include δ15N (salmon abundance),
carbon, nitrogen, and loss-on-ignition (organic matter), δ13C and C:N ratios (origin of organic matter), biogenic
silica (algal productivity), and pollen (vegetation assemblages), in addition to chronological control (14C dating) and
other sediment characteristics (magnetic susceptibility, bulk density). Because 20th century salmon abundance has
been correlated with regional sea-surface temperatures (SSTs), we compared our salmon reconstruction to existing
millennial-length reconstructions of Pacific SSTs. Results indicate that salmon abundance has declined over most of
the record as SSTs increased; a finding that is consistent with modern short-term salmon-climate relationships.
However, this relationship decoupled around AD 1400, as both salmon abundance and SSTs increased. Despite the
observed decline in historic salmon abundance, our results indicate that modern populations at the site are higher
than they have been in the last 3000 years.
LAKE SEDIMENT RECORDS OF MULTIDECADAL/CENTENNIAL-SCALE HYDROLOGIC
VARIABILITY IN CALIFORNIA FOR THE LAST 2000 YEARS
Steve Lunda, Matt Kirbyb, Larry Bensonc, Ellen Platzmana, Sarah Feakinsa
a
Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, USA
Department of Geological Sciences, California State University, Fullerton, CA 92834, USA
c
US Geological Survey, 602 Pine St Boulder, CO 80302, USA
b
E-mail address: slund@usc.edu
We present an updated comparison of California (and western-most Nevada) lake sediment records for the last 2000
years that each have multiple, independent proxy records for hydrological variability. The individual lake records
(Pyramid Lake and Walker Lake in Nevada; Mono Lake, Owens Lake, and Zaca Lake in California) have been
dated using both radiocarbon and paleomagnetic dating methods and are regionally correlatable on a scale of ±50
years. In all of the records, we see clear evidence for synchronous multidecadal and centennial-scale hydrologic
variability over the last 2000 years. Some of the records also have evidence for ENSO-scale hydrologic variability.
The most distinctive feature of these records is clear evidence for persistent recurrence of droughts 10-30 years in
duration. This variability occurs during the Little Ice Age and Medieval Warm Period, as well as times before and
after. There is some evidence that the Little Ice Age had more storminess than average and the Medieval Warm
Period had stronger droughts than average.
COMPLEMENTARY SEASONAL BIAS IN RECORDS OF HOLOCENE PALEOCLIMATE, BEAR
RIVER RANGE, SOUTHEAST IDAHO
Zachary Lundeena, Andrea Brunelleb
a
b
Rio Mesa Center and Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
E-mail address: z.lundeen@utah.edu, andrea.brunelle@geog.utah.edu
Two co-located independent paleoclimate records from the Bear River Range, southeast Idaho, have been used to
better understand seasonal variations in paleoclimate through the Holocene. A speleothem stable isotope record from
Minnetonka Cave is presented in conjunction with pollen and charcoal records from Plan B Pond, a small sub-alpine
lake located near Minnetonka Cave. The speleothem record is shown to be a strongly winter biased paleoclimate
archive, while the lake record shows different seasonal bias, depending on the proxy being evaluated (pollensummer biased, charcoal-winter biased). Together these records indicate that our understanding of Holocene
hydroclimatic variability in the West may be obfuscated when spatial anomalies are inferred from paleoclimate
records that have not been properly filtered for seasonal bias. This is particularly relevant when trying to understand
past ENSO or PDO variability inferred from winter-dominant precipitation anomalies.
TREE-RING RECONSTRUCTED HYDROCLIMATE OF THE UPPER KLAMATH BASIN
Steven B. Malevicha,b, Connie A. Woodhousea,b, David M. Mekoa
a
b
Laboratory of Tree-Ring Research, The University of Arizona, Tucson, AZ 85721-0058, USA
Department of Geosciences, The University of Arizona, Tucson, AZ 85721-0058, USA
E-mail address: malevich@email.arizona.edu
This work presents the first tree-ring reconstructions of hydroclimate for the Upper Klamath River basin, which
stretches through northern California and southern Oregon. The record gives a centuries-long view of the region’s
hydroclimate and context for water policy issues that have risen in recent years. Reconstructions of water year
precipitation for Klamath Falls, Oregon (1564 – 2004 and 1000 - 2010 CE) were created to contrast reconstructed
drought severity with droughts of the observed record. The reconstructions hint that variability during the observed
period captures moderate-to-long duration (six-, ten-, and twenty-year average) droughts, but it is likely that short
(one- and three-year average) and very long (fifty-year average) dry periods were more severe during the elevenththrough-thirteenth centuries. Evidence for the late-sixteenth century “mega drought” is found in the Klamath basin,
though with less strength than in the neighboring Sacramento River basin. Cool-season storm tracks are likely a
direct driver of hydroclimatic variability, leading to events with see-saw like relationships between the Klamath and
neighboring regions, such as during the fourteenth century, yet the vast region of drought in the twelfth century is
suggestive of a long-term northward shift in cool-season storm tracks.
ASSESSING MODERN CLIMATIC CONTROLS ON SOUTHERN SIERRA NEVADA PRECIPITATION
AND SPELEOTHEM δ18O
Staryl McCabe-Glynna, Kathleen R. Johnsona, Court Strongb, Max Berkelhammerc
a
Department of Earth System Science, University of California-Irvine, Irvine, CA 92697, USA
Department of Atmospheric Sciences, University of Utah, UT 84112, USA
c
Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, USA
b
E-mail address: mccabegs@uci.edu, kathleen.johnson@uci.edu, court.strong@utah.edu,
Max.Berkelhammer@colorado.edu
Precipitation in the southwestern United States (SW US) is highly seasonal and exhibits inter-annual to inter-decadal
variability. A 1154-year δ18O time series obtained from a southwestern Sierra Nevada stalagmite from Crystal Cave,
CRC-3, (36.59°N; 118.72°W; 1386 m) reveals substantial decadal to multi-decadal variability closely linked to the
Pacific Decadal Oscillation (PDO), and more specifically, to sea surface temperatures (SSTs) in the Kuroshio
Extension region, which impact the atmospheric trajectory and isotopic composition of moisture reaching the study
site. The instrumental portion of the CRC-3 δ18O time series suggests that more negative precipitation δ18O values
are delivered from higher latitudes during positive phases of the PDO and/or when SSTs in the Kuroshio Extension
region are anomalously cool, such as during La Niña events.
In order to improve our understanding of the controls on speleothem δ18O in this region, we have conducted a
detailed modern study of the climate, hydrology, and stable isotopic composition of meteoric waters (precipitation
and drip water) at the cave. Here we present Crystal Cave drip logger results from AD 2010 to 2011, the isotopic
composition of National Atmospheric Deposition Program precipitation samples collected from 2001 to 2011 from
Sequoia National Park-Giant Forest (Ca75), AD 2005-2011 from other locations near our site including Yosemite
National Park (Ca99), and the isotopic composition of cave drip water and glass plate calcite. The Crystal Cave drip
logger results demonstrate a low drip rate variability between July 2010 and July 2011, averaging ~20 drips/hour,
but we observe a significant increase during three storms, with the greatest increase occurring during an
'Atmospheric River' event, a type of storm known to transport large quantities of water vapor and produce extreme
precipitation in coastal regions. We compare the δ18O values in the precipitation from these three storms to satellite
imagery, NCAR/NCEP data, and NOAA Hysplit Model backward trajectories.
LINKING HOLOCENE HYDROLOGIC EVENTS WITH EPISODIC PERIODS OF FLUVIAL
DEPOSITION AND SOIL FORMATION, SANTA CATALINA ISLAND, CALIFORNIA
Eric V. McDonald, Thomas F. Bullard, Jose Luis Antinao
Division of Earth and Ecosystem Sciences, Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, USA
E-mail address: emcdonal@dri.edu
Development of records of Holocene climate variation and an increasing recognition of extreme storm events in
southern California (e.g. atmospheric rivers) allows evaluation of the linkages between hydrologic events and
geomorphic response in semi-arid settings. Alluvial stratigraphy and soils were characterized along ephemeral axial
and tributary streams across Santa Catalina Island. Soil-stratigraphy associated with surficial deposits, ranging in
thickness from 2 to 8 m, provides an excellent record of Holocene periods of hillslope instability and associated
aggradation along stream channels. The robust fluvial record contains multiple buried soils which help identify
episodes of alluvial deposition. Radiocarbon dates indicate two periods of channel aggradation, consisting of pebblegravel deposits overlying bedrock channels, occurred from 6825 to 6715 cal yr BP and possibly from 5540 to 4950
cal yr BP. This was followed by multiple discrete episodes of widespread deposition with the last three episodes
occurring between about 3305 to 2545 cal yr BP, between 1075 to 920 cal yr BP, and between 780 to 230 cal yr BP.
Available radiocarbon dates and soil stratigraphy observed in the major watersheds on Santa Catalina Island
consistently show episodic deposition that is linked to hillslope-derived sediments. Initial analysis of soil
stratigraphy and records of Holocene climate change in the San Bernardino Mountains and the Santa Barbara Basin
suggest that periods of fluvial aggradation are related to periods of intense storm activity, possibly associated with
periods of increased wildfire activity. In comparison, more than one hundred years of intense grazing that caused
widespread vegetation removal (noted in historic documents and photographs) had limited geomorphic response
(intact, well-developed hillslope soils and a sparse historic depositional record) despite record precipitation events
during the period of grazing. This suggests that Holocene climate perturbations affected the magnitude of
geomorphic responses more profoundly than is observed historically.
THE LATE HOLOCENE DROUGHT: A PERSISTENT DRY PERIOD BETWEEN 2800 AND 1800 CAL
YR BP ACROSS THE CENTRAL GREAT BASIN
Scott Mensinga, Saxon Sharpeb, Irene Tunnoc, Don Sadab, Jeremy Smitha, Jim Thomasb
a
Department of Geography, University of Nevada, Reno, NV 89557, USA
Division of Hydrologic Sciences, Desert Research Institute, Reno, NV 89512, USA
c
DAFNE, Tuscia University, Viterbo, 01100, Italy
b
E-mail address: smensing@unr.edu
Two periods of severe and persistent Holocene drought are widely recognized and well-documented in the Great
Basin of the western United States; the Middle Holocene dry period about 7500 to 5000 cal yr BP and the Medieval
Climate Anomaly between 1200 and 750 cal yr BP . Much less attention has been paid to a potentially equally
severe and persistent late Holocene dry period between ~2800 and 1800 cal yr BP. This potential drought period has
been described previously in the literature, but its magnitude and extent remain uncertain. The purpose of this paper
is to present new pollen and mollusk evidence from Spring Valley in eastern Nevada that supports the presence of a
late Holocene multi-centennial drought in the Great Basin and to compare these results with regional studies to
constrain the temporal and geographic extent of this event. A suite of evidence from sites extending from the eastern
Sierra Nevada to the Great Salt Lake all provide evidence for an extended dry and cool period between ~2800 and
1800 cal yr BP, including lake levels, faunal remains in cave deposits, pollen, chironomids, treeline studies, glacial
studies, and geomorphology. The northern Great Basin (north of ~40o N) experienced increased precipitation
through most of this period, while the southwest experience fewer flooding events. A cool dry southwest and wet
northwest is consistent with a negative SOI and persistent La Niña dominated circulation pattern. This period, which
is beyond the reach of most tree-ring chronologies, may represent a third important persistent Holocene drought and
may deserve closer attention to understand the long-term dynamics of Holocene climate change in the western
United States.
THE PLEISTOCENE CLIMATE RECORD IN ALLUVIAL FANS OF THE MOJAVE DESERT
David M. Millera, Andrew Cyra, Christopher Mengesb, Kevin M. Schmidta, Shannon A. Mahanc, Katherine Maherd,
Tanzhuo Liue
a
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94536, USA
US Geological Survey, 520 N. Park Ave., Tucson AZ 85719, USA
c
US Geological Survey, Box 25046, DFC, Denver, CO 80225, USA
d
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA
e
LDEO, Columbia University, Palisades, NY 10964, USA
b
E-mail address: dmiller@usgs.gov
Alluvial fans have been suggested as records of climate information because episodes of fan deposition are linked to
landscape processes driven by climate events. Alluvial fans are approximately synchronous, as determined by soilsgeomorphic methods, across semi-arid regions that currently exhibit ranges of climatic, geomorphic, and tectonic
conditions. Thus, synchroneity of past fan aggradation was likely driven by climate. Applications of this concept to
the widespread and fairly well dated alluvial fans of late Pleistocene and Holocene age have met with modest
success.
We compiled nearly 200 numerical ages for middle and late Pleistocene alluvial fans determined by
cosmogenic, radiocarbon, U-Th series, luminescence, and varnish microlamination methods. Fans dated by multiple
methods indicate a good correspondence among the methods. The results show a nearly monotonic decrease in the
number of ages from 700,000 to 20,000 years ago. However, peaks within the data suggest three pulses of fanbuilding: from ~930,000 to ~500,000, ~235,000 to ~125,000, and ~105,000 to ~20,000 years ago. The latter two
each can be subdivided into two or more sub-pulses but the statistical validity of some sub-pulses is weak. Timing
for fan aggradation is increasingly difficult to discern with increasing age because fewer fans are dated and the ages
have lower precision. Climate correlations are suggested by correspondence of some fan pulses and sub-pulses with
MIS 6, 4, and 2, but other pulses apparently coincide with interglacial periods, suggesting that multiple climate
drivers cause alluvial fan aggradation.
HOW CAN POLLEN AND GEOCHEMICAL EVIDENCE FROM LAKE SEDIMENTS PROVIDE
CONTEXT FOR THE CLIMATE-MEDIATED BARK BEETLE OUTBREAK OCCURRING IN
WESTERN NORTH AMERICA?
Jesse L. Morrisa,b, Peter C. Le Rouxc, Andrea Brunelled
a
College of Natural Resources, University of Idaho, Moscow, ID 83844, USA
Department of Geography, Kansas State University, Manhattan, KS 66506, USA
c
Department of Geosciences and Geography, University of Helsinki, Finland 00014
d
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
b
E-mail address: jlmorris@uidaho.edu
In recent decades irruptive populations of native bark beetles (Dendroctonus spp.) damaged 47 million ha of
coniferous forest in western North America. The scale and severity of this outbreak is unprecedented at least since
Euro-American settlement. Climate warming is cited as the primary driver of this outbreak for two reasons: 1) beetle
reproductive strategies accelerate during pervasively warm periods; and 2) milder winters promote greater survival
of overwintering beetles. However, in subalpine forests stand-replacing disturbances, such as wildfire, often recur at
time intervals that exceed historical observations, raising the possibility that outbreaks of comparable magnitude
may have occurred prior to settlement. Our research investigates the recent outbreaks to improve understanding of
the drivers, outcomes, and long-term dynamics of beetle disturbances. We examined sediments from six subalpine
basins in Utah from spruce/fir forests (Picea engelmannii/Abies lasiocarpa) that were severely affected by spruce
beetle (D. rufipennis). Sediments were analyzed for pollen, macrofossils, loss-on-ignition, magnetic susceptibility,
δ13CBOM, δ15NTN, elemental C and N, and the C/N ratio. We hypothesize that the post-outbreak mortality and
subsequent defoliation of spruce will: 1) decrease the ratio of spruce to fir pollen; 2) reduce canopy interception of
precipitation, facilitating an increase in soil erosion and mobilization of terrestrial C; and 3) enable leaching of foliar
N thereby promoting algal productivity. We tested our dataset using general linear mixed models (GLMMs) to
determine if the response variables differed significantly between outbreak and non-outbreak periods. The spruce/fir
pollen ratio decreased significantly at all sites during outbreaks suggesting that this metric may be suitable to detect
past outbreaks (hypothesis 1). We found no support for an influx of minerogenic material and terrestrial C
potentially due to differences in catchment structure (hypothesis 2). We found little evidence for increased N
following outbreaks which is likely attributable to human activities and/or uptake of N by the residual terrestrial
community (hypothesis 3). To examine the assumption that climate is the primary driver of the recent outbreaks, we
compare the spruce/fir pollen ratio (hypothesis 1) with spruce biomass calculated using USFS stand inventory data
and a pollen transfer function to reconstruct forest conditions in two watersheds over the last 300 years.
20TH CENTURY RAINFALL PATTERNS OF THE SANTA BARBARA REGION ASSEMBLED FROM
SEDIMENT PROVENANCE ANALYSIS OF A SANTA BARBARA BASIN BOX CORE.
Tiffany Napiera, Ingrid L. Hendya, Arndt Schimmelmannb
a
b
Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI 48109, USA
Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA
E-mail address: tinapier@umich.edu
Rainfall patterns in southern California directly affect the availability of water resources and extreme weather
exacerbates water stress and societal impacts. California has a Mediterranean climate characterized by wet winters
and warm, dry summers. Heavy rainfall associated with atmospheric rivers causes flooding and can lead to
landslides, while drought conditions lead to agricultural water rationing and a landscape susceptible to wildfires.
Reconstruction of paleo-precipitation patterns provides knowledge on the frequency, and the temporal and spatial
extent of these extreme events, required for adaptation and mitigation planning for southern California. In this study
we reconstruct 20th century precipitation history of river catchments adjacent to the Santa Barbara Basin (SBB)
through ultra-high resolution elemental analysis of box core SPR0901-4BC. The Santa Ynez Mountain drainages,
the Ventura River catchment, and the Santa Clara River catchment all discharge into SBB. Watershed sediment is
mostly derived from Cenozoic sedimentary units, but the Santa Clara River catchment contains metamorphic and
igneous units that distinguish it from the other catchments. Preliminary investigations based on scanning XRF
analysis at 200 µm intervals accommodate five to seven analyses per year providing evidence of annual changes in
elemental composition of core sediment. The highest counts of Ti, K, Fe, Al, Si, and Rb (i.e. elements associated
with siliciclastic sediment) occur during wet years and relate to significant river runoff events. The relative
proportion of elements within each event is not consistent between events, possibly reflecting differences in
temporal and/or spatial rainfall patterns that cause differences in the response of the various river catchments
draining into SBB. We will analyze clay suites in the core and compare them to the elemental data in order to further
elucidate provenance and determine if wet year layer sediment is sourced from Santa Ynez Mountains and(or) the
San Gabriel Mountains (Santa Clara River catchment). Temporal trends in the provenance data will be analyzed
such that an ultra-high temporal and spatial reconstruction of precipitation patterns for southern California can be
undertaken.
HOLOCENE LAKE-LEVEL HISTORY OF TULARE LAKE, CALIFORNIA AS INPUT FOR SIERRA
NEVADA RIVER DISCHARGE FORECASTS: PROGRESS REPORT
Rob Negrini
Department of Geological Sciences, California State University, Bakersfield, CA 93311, USA
E-mail address: rnegrini@csub.edu
Fed mainly by large Sierra Nevada rivers (Kings, Kaweah, Tule, and Kern), Tulare Lake was the largest freshwater
lake west of the Great Lakes. The lake essentially dried up starting in the late 19th century when discharge from
these rivers was diverted for irrigation purposes. Prior to this time, lake level was dependent principally on the
discharge of these rivers as per the hydrologic balance model presented in Atwater et al. (1986). Turning this
around, a paleolake-level history could be used to estimate paleorunoff. In turn, when compared to paleorecords of
Sierra Nevada precipitation drivers (e.g. sea-surface temperatures), a paleorunoff record could in principle be used
to establish a more or less direct link between SSTs and river discharge from the Sierra Nevada into the southern
San Joaquin Valley. Finally, this link would establish a basis for forecasting water supplies into one of the world’s
most important agriculture centers in response to expected changes in SSTs over the next several decades. Toward
this end a series of cores, outcrops and trenches excavated into the top few meters of Tulare Lake deposits are
converging on a common lake level history consisting of four episodes of relatively large lakes in the Holocene
including a large lake that persisted from the 13th through the 18th century AD. Relative lake-level proxies based on
geochemical and physical analyses of core sediment are consistent with trench-based observations of nearshore
deposits. Ongoing work on a new set of outcrops in a region that has never been farmed will incorporate
paleomagnetic secular variation to supplement radiocarbon dating. The top 3 m of lake sediments are exposed in
these outcrops along a 1.5 km long rim of a borrow pit on the Pixley National Wildlife Refuge.
Atwater, B.F., Adam, D.P., Bradbury, J.P., Forester, R.M., Mark, R.K., Lettis, W.L., Fisher, G.R., Gobalet, K.W.,
Robinson, S.W., 1986. Fan dam for Tulare Lake, California and implications for the Wisconsin glacial of the Sierra
Nevada. Bulletin of the Geological Society of America 97, 97-109.
HOLOCENE PALEOCLIMATE POTENTIALOF FALLEN LEAF LAKE SEDIMENT CORES, TAHOE
BASIN, CALIFORNIA, USA
Paula J. Noblea, G. Ian Ballb, Shane B. Smitha, Susan H. Zimmermanc
a
Department of Geological Sciences and Engineering, University of Nevada Reno, Reno, NV 8955, USA
Scripps Institute of Oceanography, Geosciences Research Division, La Jolla, CA 92093, USA
c
The Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550,
USA
b
E-mail address: noblepj@unr.edu, gball@ucsd.edu, zimmerman17@llnl.gov
We present preliminary analyses of three Fallen Leaf Lake cores collected in AD 2010, including stratigraphic
correlations, an age model based on AMS radiocarbon and 210Pb, organic geochemistry, elemental geochemistry
from scanning X-ray fluorescence (XRF), and diatom analyses. Gross lithologic packages observed include silty late
Tioga glacial outwash through 12,500 cal yr BP, a lower laminated interval of greenish opaline clay (~12,500-9800
cal yr BP), a weakly laminated interval below the Tsoyawata ash (~9800-7800 cal yr BP) during the early Holocene
wet period, and a mottled interval (7700-~3700 cal yr BP) during the middle Holocene dry period that grades into a
homogeneous olive opaline clay (~3700 cal yr BP-present). Turbidites are a minor core component, but have a
strong terrestrial signature with higher total organic carbon (C) to organic nitrogen (N) and lower total wt% C and
N. Baseline shifts are observed in wt% C, N, δ13C, and δ15N circa 7300, 5000, and 3700cal yr BP and coincide well
with sedimentation shifts that may reflect major changes in middle Holocene aridity. The XRF data of interest
include Si/Ti, a proxy for biogenic silica, and incoherent:coherent scattering, a proxy for light elements, particularly
organic matter, both of which show similar trends to the organic geochemical data. The Fe, Mn, Ca, Ti, and K show
strong intensity peaks in the turbidites and ash, and also show interesting baseline shifts and inflections at 5000,
3700, 3200, and 1800 cal yr BP. Diatom assemblages are diverse (>180 species), with much of the alpha diversity
attributed to lotic periphyton that were washed infrom the upper watershed. Diatom assemblages vary down-core,
largely due to fluctuations in % A. subarctica, cyclotelloids, and % periphyton, and may reflect changes in mixing,
stratification, and stream inflow. These cores provide a continuous Holocene record and show potential to integrate
a wide array of proxies to resolve aspects of climatic history in the Lake Tahoe Basin back to 13,300 cal yr BP.
INTERANNUAL AND LONGER VARIABILITY IN CENTRAL CALIFORNIA KELP FORESTS
Jerrold G. Norton, Janet E. Mason
Environmental Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA. 1352
Lighthouse Avenue, Pacific Grove, CA 93950, USA
E-mail address: Jerrold.G.Norton@noaa.gov
Kelp (Macrocystis spp., Nereocystis luetkeana) marine forests are globally distributed, exceptionally productive and provide
complex structure for highly diverse ecosystems. Their shallow water habitat (<25 m) off southern California may have
varied as much as 500% during the last 20,000 years. Twentieth century monitoring of California kelp has shown that
variations of similar magnitude may occur in individual kelp beds due to wave action, predation, sediment transport,
pollution, temperature and nutrient availability. Kelps develop from holdfasts with stipes or stems that develop blades and
flotation bladders. Stipes reaching the surface may continue to elongate and lay on the surface forming a canopy. We
examined patterns of interannual variation at maximum annual kelp development and its uniformity over scales of 100 km;
assuming that maximum annual development is represented by late summer or fall measurements of canopy surface area and
stipe density. Initially we examine the AD 2002 - 2005 period when aerial and subsurface observations are available.
Interannual kelp patterns during AD 2002-2005 were similar from Pt. Estero to Pt. Año Nuevo (northern area). This four-year
pattern was characterized by highest stripe density and most extensive canopy coverage in AD 2002. In contrast, AD 20022005 kelp development around the Santa Barbara Channel Islands was lowest in AD 2002. A transitional area was found
between Pt. Estero and the Channel Islands. Stipe density for AD 1999-2010 shows periods when the northern and Channel
Island kelp beds had opposite interannual developmental tendencies, but in some periods these two areas appear to respond in
similar ways to spatial variability in nutrient supply mediated by local ocean processes. Understanding these modes of
interannual variability will be key to analyzing the effects of the newly established California marine protected area
networks. Because kelp forests accumulate photosynthetic responses to ongoing physical conditions, monitoring them will
provide important inputs to area-wide integrated ecosystem analyses.
CLIMATE FREQUENCIES OF THE EARLY HOLOCENE FROM FOY LAKE, MONTANA
Deven M. O’Neila, Lora R. Stevensb
a
Department of Earth, Space, and Aviation Sciences, Palomar College, CA 92069, USA
Department of Geology, California State University, Long Beach, CA 90840, USA
b
E-mail address: devenoneil@gmail.com, lora.stevens@csulb.edu
Detailed records of cyclical, severe droughts are valuable for understanding future changes in hydrologic patterns
and to better constrain climate model simulations. An early Holocene record of cyclical drought events,
approximately 3300 years in length and with an ~5 year resolution, was reconstructed from the δ18O and δ13C values
endogenic carbonate from Foy Lake, Montana. Foy Lake resides in the present-day region of winter-wet—Pacific
Dedacal Oscillation (PDO) influence, altering general wind direction and latitudinal location of the North American
jetstream, which changes the trajectory of winter storms. Evolutive spectral analysis on the de-trended δ18O record
was used to extract reoccurring decadal to centennial-scale cycles that might be associated with synoptic climate
variability such as the PDO or Arctic Oscillation. From 10,800 cal yr BP to 9600 cal yr BP the record exhibits strong
cyclicity in the ~200 year range, which suggests a sensitivity of moisture availability to solar activity. Little
evidence exists for higher frequency variations in this period dominated by a cooler, less evaporation-based climate.
A dramatic shift towards a warmer climate occurs after 9600 cal yr BP. This shift occurs in a step pattern and is
most striking in the δ13C record. After the shift to warmer climate at 9200 cal yr BP stochastic multi-decadal
cyclicity dominates with weaker cycles ranging from 40-70 years.
PRELIMINARY TEPHROCHRONOLOGIC AND DIATOM ANALYSES FROM HOBART LAKE,
JACKSON COUNTY, SOUTHEASTERN OREGON, AND REGIONAL CORRELATIONS WITH LATE
HOLOCENE MIDDLE AND HIGH ELEVATION LACUSTRINE RECORDS FROM THE WESTERN US
Holly A. Olsona, Jennifer Kuslera, Elmira Wana, Scott W. Starratta, Christy Brilesb, Ali Whitec, Caitlyn Florentinec
a
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
Geography and Environmental Sciences, University of Colorado Denver, P.O. Box 173364, Campus Box 172,
Denver, CO 80217, USA
c
Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA
b
E-mail address: holson@usgs.gov
Volcanic ash deposits and diatom assemblages from HL04B and HL11B, two sediment cores collected in 2004 and
2011, respectively from Hobart Lake (42.0978154 N, -122.4809704 W, 1459 masl), Jackson County, southeast
Oregon, were analyzed to develop a preliminary tephrochronologic framework and to reconstruct the local
environmental history. The tephrochronology was also used to constrain the timing of, and correlate climatic events
from the northeastern Pacific Ocean to across the western conterminous US and beyond. To date, the ~7700 cal yr
BP Mazama ash and the youngest (940-890 cal yr BP) Glass Mountain ash beds have been identified in these two
cores. The respective volcanic source areas for these volcanic ash layers are prehistoric Mount Mazama in Crater
Lake caldera, Oregon, and Glass Mountain in Medicine Lake volcano (MLV) caldera, northeastern California.
Diatom proxy data infer that significant shifts in environmental conditions occurred prior to, and after the Mazama
and Glass Mountain eruptive events. As a result, we used the widespread Mazama ash as a timeline to temporally
bracket and attempt to regionally correlate paleoenvironmental events. Thus far, we have identified the Mazama ash
in marine cores from offshore Washington to middle and high elevation lakes throughout the western regional US
(e.g. Hobart Lake, and Crater Lake in Oregon, Swamp Lake (Yosemite National Park), and Medicine Lake in
California, Favre, Overland, and Soldier lakes in the Ruby Mountains, Nevada, Cosley Lake, Glacier National Park,
Montana, among other locations. At Hobart Lake, the Mazama ash was originally deposited in a relatively deep (>5
m) lake in which the diatom flora was dominated by planktic taxa (Cyclotella and Stephanodiscus). Over time, as
the lake decreased in depth, the flora became predominantly benthic, with increased abundances of small fragilarioid
mat-forming taxa (Fragilaria, Staurosira, Staurosirella). During the last ~1000 years, primarily epiphytic taxa
(Cocconeis, Cymbella, Gomphonema) were deposited indicating that in the latest Holocene, aquatic macrophytes
predominate Hobart Lake.
Diatom records from Medicine Lake, Swamp Lake, and Favre Lake follow a different paleoenvironmental
history. These lakes are shallow during the early Holocene, with an assemblage that is dominated by benthic taxa.
Medicine Lake gradually fills during the middle Holocene, and then fluctuates in depth by a few meters during the
late Holocene. Favre Lake is dominated by small fragilarioid mat-forming species throughout most of the middle
and late Holocene. Planktic species become a more significant component of the flora only during the last 500 years
of the record. Swamp Lake is dominated during much of its record by deeper (>5 m) conditions. These differences
may be attributed to local environmental factors, such as moisture availability, nutrient load, differences in
temperature, pH, etc., as well as analytical artifacts due to comparatively higher resolution at some core sites. Future
research will clarify and increase our understanding of the similarities and variability between these sites. It will also
help to refine reconstructed local and regional limnologic and climatic histories.
HOLOCENE PRECIPITATION VARIABILITY RECORDED IN δ18O AND U ISOTOPES OF OPAL
SPELEOTHEMS FROM PINNACLES NATIONAL MONUMENT, CALIFORNIA
Jessica L. Ostera, Katharine Maherb, Kouki Kitajimac, John Valleyc, Bruce Rogersd
a
Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240, USA
Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305, USA
c
Department of Geoscience, University of Wisconsin, Madison, WI 53706, USA
d
Cave Research Foundation, USA
b
E-mail address: jessica.l.oster@vanderbilt.edu
Past environmental changes are often reconstructed using records of oxygen isotope variability (δ18O) in
speleothems. However, δ18O may be influenced by a combination of environmental factors including rainfall
amount, temperature, and moisture source. Variations in initial uranium isotopic values ((234U/238U)0) reflect changes
in net infiltration - precipitation minus evapotranspiration (P-ET) - and thus provide a paleoclimate proxy that is
sensitive to past changes in rainfall. Combined investigation of (234U/238U)0 and δ18O in the same materials could
provide records of variations in P-ET and allow differentiation of the influence of effective moisture on δ18O values
from other factors such as moisture source. Opal speleothems from a talus cave at Pinnacles National Monument
(PNM) in California have high U concentrations that permit the development of a 230Th-U chronology and
(234U/238U)0 record using in situ secondary ion mass spectrometry (SIMS) on the same spatial scale as a record of
δ18O variability also produced using SIMS techniques. Modern rainfall δ18O at PNM displays a significant negative
correlation with relative humidity but is also linked to moisture source. Thus, combined, high spatial resolution
records of speleothem (234U/238U)0 and δ18O from PNM should allow independent investigation of potential changes
in rainfall and moisture source in central California.
The 230Th-U opal ages of the PNM speleothems suggest a growth interval of 15,700 to 2700 yr BP, with some
possible depositional shifts to calcite. The age-corrected (234U/238U)0 values decrease from 15,700 to 13,000 yr BP,
increase by ~0.2 through the early Holocene to reach a maximum between 7000 and 6000 yr BP, and remain steady
for the remainder of the record until ~2700 yr BP. Speleothemδ18O values also gradually rise by ~0.75 ‰ through
the early Holocene to reach a maximum at approximately 7000 yr BP, yet decrease following this by the same
amount to the end of the record. A quantitative model of (234U/238U) in modern soil waters indicates that the
magnitude of change observed in the PNM speleothem is consistent with an initial increase in P-ET of 2% followed
by a decrease of 10% between approximately 13,000 and 7000 yr BP. Peak aridity at PNM between 7000 and 6000
yr BP is consistent with paleoclimate records from western North America that suggest dry and warm conditions
during the middle Holocene. Increased δ18O may also result from increasing aridity. However, the decrease in PNM
δ18O following 7000 yr BP, while (234U/238U)0 remains flat, may reflect a shift toward more northerly sourced
rainfall in central California. The PNM speleothem highlights the potential of (234U/238U)0 to unravel multiple
influences on records of δ18O variability.
FORAMINIFERAL PROXY RECORDS OF SEA SURFACE TEMPERATURE CHANGES OVER THE
LAST 2000 YEARS IN SANTA BARBARA BASIN, CALIFORNIA
Dorothy K. Paka, Arndt Schimmelmannb, Ingrid L. Hendyc, Jennifer Reynoldsa
a
Marine Science Institute, University of California at Santa Barbara, Santa Barbara CA 93106, USA
Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA
c
Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA
b
E-mail address: pak@geol.ucsb.edu, aschimme@indiana.edu, ihendy@umich.edu
Deciphering climate history from ocean sediments is dependent on our understanding of the various influences on
marine proxies. On the California margin, proxy records of sea surface temperature over the last 2000 years yield
apparently conflicting results, with foraminiferal oxygen isotopic records and marine floral records indicating
relatively warm conditions during the Little Ice Age while foraminiferal faunal and Mg/Ca records indicate cooler
conditions. High quality box and kasten cores from Santa Barbara Basin provide an opportunity to link foraminiferal
proxy records to the instrumental sea surface temperature record over the past 200 years, and to extend these proxy
temperature records back over the last 2000 years.
We present an approximately annual to decadal record of size-normalized shell weight, Mg/Ca and δ18O of the
near-subsurface dwelling planktonic foraminifera Globigerina bulloides in Santa Barbara Basin, California (34°
16.847’ N, 120° 02.268’ W), over the last 2000 years. Results indicate that foraminiferal shell weight is inversely
correlated with instrumental sea surface temperature since 1850. Foraminiferal shell weights were highest between
1900 and 1920, corresponding to the lowest instrumental sea surface temperatures. Shell weights gradually
decreased to their lowest values after the mid-1970s, coincident with northeast Pacific warming as the Pacific
Decadal Oscillation shifted from cool to warm phase. G. bulloides Mg/Ca temperatures are approximately 2° C
cooler than instrumental temperature records over the past 150 years, consistent with previous work suggesting a
depth habitat of 20-30 meters. Globigerina bulloides δ 18O trends are broadly similar to the Mg/Ca and shell weight
records between 1850 and 2000.
From 0 to AD 1000 Mg/Ca-derived temperatures were relatively stable and similar to modern warm season
temperatures. The first half of the Medieval Climate Anomaly (MCA; AD 700 to 1000) was relatively warm (1516°C), cooling by approximately 2°C by the by the end of the MCA (AD 1300). The Mg/Ca derived temperatures
continued to cool through the Little Ice Age (LIA) until approximately AD 1600. Coolest temperatures of the last
2000 years occurred between 1825 and 1850 and from 1949 to 1952. The Mg/Ca-derived temperatures gradually
increased after 1952, with the warmest temperatures occurring after 1970. G. bulloides shell weight trends are
broadly similar to the Mg/Ca record between 1850 and 2000, with low shell weights corresponding with high Mg/Ca
values. Prior to 1850, however, Mg/Ca and shell weight show significant differences, with shell weights increasing
from AD 600 to 1100 and decreasing from the late MCA (AD 1100 to 1300) and through the LIA.
CALIFORNIA GLACIERS
Tim Palmer
Independent travel writer
E-mail address: tim@timpalmer.org
Nestled high in the mountains of California among snowy peaks, alpine forests, and flowing rivers lies an age-old
phenomena that is slowly fading from existence: the glaciers of California. This stark world of slow-moving ice has
nourished our state’s rivers and habitats, has provided water to our farms and cities, and sustains life as we know it.
A victim to climate change, California’s glaciers are receding at an alarming rate. Award-winning
photographer and nature writer Tim Palmer takes us on a trek into the backcountry to experience the remaining
glaciers up close, to observe the raw power that for millennia has carved glacial valleys, replenished our lakes,
rivers, and streams, and supported a bounty of life that may soon be in jeopardy with the loss of one of the states
most vital and awe-inspiring natural wonders.
RADIOCARBON DATING OF LATE QUATERNARY SEDIMENTS USING FOSSIL GASTROPOD
SHELLS
Jeffrey S. Pigatia, John P. McGeehinb, Daniel R. Muhsa
a
b
US Geological Survey, Denver Federal Center, Box 25046, MS-980, Denver, CO 80225, USA
US Geological Survey, 12201 Sunrise Valley Drive, MS-926A, Reston, VA, 20192, USA
E-mail address: jpigati@usgs.gov
Terrestrial gastropods are one of the most successful groups of organisms on Earth. Their distribution includes all
continents except Antarctica, and they occupy exceptionally diverse habitats, from marshes and wet meadows to
alpine forests and Arctic tundra. Their shells are also commonly preserved in Quaternary deposits and potentially
could be used for 14C dating. However, terrestrial gastropods are known to ingest limestone and incorporate the old
carbon in their shells, resulting in apparent ages that are often too old. Recent studies have shown that many small
(<1 cm diameter) terrestrial gastropods avoid this “limestone problem” even when living in areas in which carbonate
rocks are readily available. However, the shells must also behave as closed systems with respect to carbon if their
ages are to be considered reliable. Our latest work has been aimed at testing if small gastropod shells do, in fact,
remain closed systems in late Quaternary deposits over a wide array of climate conditions across North America.
Our results demonstrate that ages derived from Succineidae shells are identical to wood and charcoal ages in loess in
Alaska, glacial deposits in the upper Midwest, loess in the Great Plains, and paleowetlands in the desert southwest.
Moreover, Succineidae shell ages routinely fall within permitted limits set by stratigraphic boundaries, require less
interpretation than humic acid ages that are commonly used in loess studies, can provide additional stratigraphic
coverage to previous dating efforts, and maintain stratigraphic order more often than luminescence ages from the
same stratigraphic intervals. Thus, we conclude that fossil Succineidae shells, and shells of a few other small
gastropods, can be used for 14C dating regardless of the local lithology, past climate, or environmental conditions.
A 1500 YEAR RECORD OF HYDROLOGIC VARIABILITY IN THE NORTHWESTERN GREAT BASIN
FROM SEDIMENTS IN BIG SODA LAKE, CHURCHILL COUNTY, NEVADA
Liam Reidya, Roger Byrnea, Lynn Ingram,b Michael Rosenc, Susan Zimmermand, Marith Reheise
a
Department of Geography, University of California, Berkeley, CA 94720, USA
Department of Earth and Planetary Sciences, University of California, Berkeley, CA 94720, USA
c
US Geological Survey, 2730 North Deer Run Road, Carson City, NV 89701, USA
d
CAMS, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
e
US Geological Survey, PO Box 25046, DFC, Denver, CO 80225, USA
b
E-mail address: lreidy@berkeley.edu, arbyrne@berkeley.edu, ingram@eps.berkeley.edu, mrosen@usgs.gov,
zimmerman17@llnl.gov, mreheis@usgs.gov
A 1500-year record of hydrologic and climate variability for the Carson Sink area of northwestern Nevada was
developed from multiproxy analyses of the upper 2 m of laminated sediment recovered from Big Soda Lake, a
volcanic crater lake near Fallon, Nevada. High resolution δ18 O from calcite and XRF data from sediments indicate
several sub-decadal, decadal, and centennial changes in lake levels during the past 1500 years. The high resolution
data and lake level reconstructions are supported by an independent chronology provided by Pb210, radiocarbon, and
two dated tephras. Oscillations in the oxygen isotopic and geochemical record during the pre-historic period indicate
regional climate shifts associated with cooler and wetter conditions during ca. AD 500-850, 1175-1300, and 16751775. Above modern average warmer and drier conditions prevailed for the periods AD 875-1175, 1325-1500, and
1600-1675. The abrupt change in the δ18 O and XRF data near the top 7 cm of the record marks the introduction of
fresh groundwater to the lake after the construction of Lahontan Dam in the early 20th century. The Big Soda Lake
record is in general agreement with results from other regional lake records including Owens, Pyramid, Walker, and
Mono Lake that show periods of warmer and drier conditions during the Medieval Climatic Anomaly (AD 950 to
1250) and cool and wetter conditions during the Little Ice Age (AD 1350 to about 1850).
A MULTI-PROXY PALEOLIMNOLOGY STUDY OF THE IMPACT OF CLIMATE CHANGE AND
ATMOSPHERIC POLLUTANT LOADINGS ON AQUATIC ECOSYSTEMS IN THE GREAT BASIN,
UNITED STATES
Scott A. Reinemanna, David F. Porinchub, Mae S. Gustinc, Bryan G. Marka
a
Department of Geography, The Ohio State University, Columbus, OH 43210, USA
Department of Geography, University of Georgia, Athens, GA 30602, USA
c
Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV 89557, USA
b
E-mail address: reinemann.2@osu.edu
The geochemistry of lake sediments was used to identify anthropogenic factors influencing aquatic ecosystems of
sub-alpine lakes in the western United States during the past century. Sediment cores were recovered from six high
elevation lakes in the central Great Basin of the United States. The proxies utilized to examine the degree of recent
anthropogenic environmental change include sub-fossil chironomids, spheroidal carbonaceous particles (SCP),
mercury (Hg), and sediment organic content estimated using loss-on-ignition (LOI). Chronologies for the sediment
cores, developed using 210Pb, indicate the cores span the 20th century. Chironomid-based MJAT reconstructions
were developed using a WA-PLS inference model based on a calibration set developed for the Inter-Mountain West
of the United States consisting of 79 lakes and 54 midge taxa (rjack2=0.55°C, RMSEP=0.9°C, maximum
bias=1.66°C). The midge communities present in the lakes experience muted compositional change through much of
the 20th century; however, the sediment deposited during the last three decades is characterized by rapid lakespecific faunal turnover. The chironomid-inferred MJAT reconstructions appear to closely track observed July
temperature in the region during the late 20th century. The Hg flux varied between lakes but all exhibited increasing
fluxes during the mid-20th century and declining fluxes during the late 20th century. The average flux ratio from
modern (post-AD 1985) to preindustrial (pre-AD 1880) was 5.2, which is comparable to the results from previous
studies conducted in western North America. Peak SCP flux for all lakes occurred at approximately AD 1970, after
which time the SCP flux was greatly reduced. Atmospheric deposition is likely responsible for the elevated inputs of
Hg and anthropogenically produced SCPs to high elevation lakes in the Great Basin during recent decades
documented in this study. Increases in the deposition of SCPs and Hg documents that significant anthropogenic
influence began during the early to mid-20th century, predating the change associated with recent inferred shifts in
thermal conditions.
WATER YEAR 2012-13: A WET START BUT HOW WILL IT END?
Maurice Roos
California Department of Water Resources, Sacramento, CA 95821-9000, USA
E-mail address: mroos@water.ca.gov
Water year 2011 was a wet year in California with a big snowpack, the fifth biggest on April 1 in 60 years. Water
supplies were excellent and well above average reservoir carryover storage helped ease supply problems in the
subsequent year which turned out dry. The big gap in precipitation in WY 2012 was the three mid-winter months,
December through February. Normally that period accounts for half the annual rainfall, but this time it was only 22
percent. A wet March allowed for some recovery from what might have been a very dry situation last year. By fall
2012 water storage had fallen below average which increased the importance of a good rainfall and runoff year in
WY 2013. The consensus of those in the long range seasonal forecasting game in September was that WY 2013
would be drier than average. This was mostly based on a projected weak or no El Niño, a strongly negative Pacific
Decadal Oscillation (PDO), ocean coolness between Hawaii and Baja California, and a relatively warm North
Atlantic. Indeed what appeared to be the start of an El Niño in the summer fizzled in the fall to a more neutral
pattern.
October had some rain but mostly less than average. But both November and December were well above
average in precipitation, more so in the north. Much of this boost came from two strong atmospheric river events
(AR, sometimes labeled pineapple express) conveying loads of moisture into northern California at the end of
November and again for four days about three weeks later in December just before Christmas. The northern Sierra
eight station group picked up about 43 cm, or about one-third the annual average, in the two events. The San Joaquin
five station Sierra group gained about 30 cm for a 29 percent chunk of the annual average total season there. As of
the end of January, we could say half the seasonal precipitation in northern California to that point came from the
two large AR events.
As often happens, California weather went into a dry pattern about the first of the year, which continued into
February. January precipitation, normally our wettest month, slid into the lowest 10 percent of years, dropping
seasonal percentages to near average by February 1. The important snowpack then was 90 percent of average, or 55
percent of the April 1 average, normally the time of maximum accumulation. Reservoir storage was 5 percent over
average on February 1, but if conditions remain dry, this percent can be expected to slip below average later in the
season, with some shortages in the San Joaquin Valley and south. Some years with a dry midwinter core show some
recovery in the spring. Most notably during the 1987-1992 drought, severe conditions in 1991 were eased by
a “miracle March” at three times normal.
SEDIMENTARY EVOLUTION OF SWAN LAKE AND ITS IMPLICATIONS FOR DEGLACIAL AND
HOLOCENE PALEOCLIMATE OF SOUTHEASTERN IDAHO
José Rosarioa, David M. Millera, David B. Wahla, Lysanna Andersona, Charlesg. Oviattb, Aradhna Tripatic, Liubov
Presnetsova, John P. Mcgeehind
a
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94536, USA
Department of Geology, Kansas State University, Manhattan KS 66506, USA
c
Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, CA 90095, USA
d
US Geological Survey, 12201 Sunrise Valley Drive, Reston, VA 20192, USA
b
E-mail address: jrosario@usgs.gov
Swan Lake is a shallow pond in southeastern Idaho formed in the former overflow channel of Lake Bonneville. We
analyzed a 7.6-m-long sediment core that was recovered in 2011 in order to evaluate the deglacial and Holocene
regional climatic history. Analyses include sediment composition (including LOI, GRA bulk density), magnetic
susceptibility, sediment accumulation record, and clumped isotopes of carbon and
∆
oxygen ( 47). Our
sedimentological data are correlated with paleoecological data from a previous study of Swan Lake with the aid of
13 new radiocarbon dates.
We observed that the Swan Lake sediment column is composed of a basal sand succeeded by seven intervals
that alternate mud and peat. The basal sand shows a bimodal grain size distribution that fines upward toward the
overlying mud. Radiocarbon ages from twigs and root fragments a few cm above the top of the sand are 13,51013,270 cal yr BP. Mud intervals change from clay-dominated below 3 m to calcium carbonate muds above. Several
energy regimes can be inferred from the sediments. The highest energy regime is represented by the basal sand
strata, which may be the result of reworking an older river deposit by wave action. The combined influence of
groundwater and surface water flux probably controlled overlying mud and peat. Radiocarbon and stratigraphic
results indicate higher deposition rates for mud (~10 yr/cm) compared to peat (~25 yr /cm). Samples from calcium
carbonate muds that were analyzed for clumped isotopes yielded preliminary summer water temperatures that
suggest waters were no warmer than 25oC during the middle and late Holocene. Present-day maximum summer air
temperatures in analog environments are similar to these water temperatures. Future work includes more clumped
isotope analyses, macroscopic charcoal, and more detailed comparison of our data with previous paleoecological
and sedimentological data from Swan Lake.
MIDDLE HOLOCENE CHANGES IN BIG SODA LAKE, NEVADA: CLIMATICALLY OR
HYDROLOGICALLY INDUCED CHANGES?
Michael R. Rosena, Liam Reidyb, Scott Starrattc, Roger Byrneb, B, Lynn Ingramd
a
US Geological Survey, 2730 North Deer Run Road, Carson City, Nevada 89701, USA
Department of Geography, University of California, Berkeley, CA 94720, USA
c
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
d
Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
b
E-mail address: mrosen@usgs.gov, lreidy@berkeley.edu, sstarrat@usgs.gov
Big Soda Lake is a Holocene maar lake located near Fallon, Nevada. It is a stratified saline lake, 63 m deep, and
currently has no surface water inputs; it is essentially a window into the groundwater record. An 8.5 m long
sediment core collected from near the center of the lake in 2010 contains millimeter-scale sedimentary laminations,
diatoms, and stable isotope data from bulk calcite that are consistent with a saline closed-basin lake down to
approximately 4.3 m below the sediment water interface. At this point, the lamination abruptly ends and is replaced
by mostly unlaminated massive grey mud, sand and gravel to the bottom of the core. The isotopic composition of the
bulk calcite abruptly changes from covarying oxygen and carbon values indicative of a closed-basin lake above 4.3
m, to inversely varying oxygen and carbon isotopic compositions below. Carbon-14 age dating of flow cytometerseparated pollen grains indicates that this abrupt break occurs at approximately 5600 cal yr BP. Below the break,
carbon-14 ages do not get older down to 7 m indicating that the core is disturbed and possibly slumped. The bottom
meter and half shows a relatively sharp increase in age with an age of the bottom sample of close to 15,000 cal yr
BP at 8.4 m depth. Although the interval between 4.3 m and 7 m depth appears highly disturbed and has similar
carbon-14 ages throughout, the sediments above and below 4.3 m are quite different. The diatom assemblage below
4.3 m is similar to assemblages found in modern Walker Lake, a brackish to fresh water lake; whereas the diatom
assemblage above 4.3 m is similar to modern Mono Lake, a saline closed-basin lake. The isotopic composition of
bulk oxygen isotope composition of the calcite is also different, and is on average 6 per mil more negative in oxygen
below 4.3 m than isotope values above the abrupt change, indicating that the lake contained fresher water 5600 cal
yr BP ago. Carbon-13 isotope values are similar across this boundary. The cause for the abrupt change is difficult to
explain through climate shifts. Although climate in the Great Basin has been shown to be more arid from 8000 to
5000 cal yr BP, this is the period of fresher water in Big Soda Lake. Research in the 1980’sshowed that the Walker
River was entering the Carson River Basin between about 14,000 and 5000 cal yr BP, and that Walker Lake was a
playa at that time. It is possible that this fresh water input in to the Carson River raised the groundwater table
sufficiently in the Carson Basin to freshen Big Soda Lake. Once the Walker River diverted back to the Walker
Basin, sedimentation patterns changed quickly and more saline conditions prevailed in Big Soda Lake. Slumping
may have also occurred as the groundwater table fell, after the Walker River input ended, contributing to the
inability to distinguish different age dates on this section of the core.
A MULTI-PROXY STALAGMITE RECONSTRUCTION OF CLIMATE IN THE CENTRAL SIERRA
NEVADA DURING THE LAST DEGLACIATION
Laura R. Santarea, Jessica L. Osterb, Isabel P. Montañeza, Kari M. Coopera, Warren D. Sharpc
a
Geology Department, University of California Davis, Davis, CA 95616, USA
Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240, USA
c
Berkeley Geochronology Center, Berkeley, CA 94709, USA
b
E-mail address: lrsantare@ucdavis.edu
Stalagmites from Sierra Nevada caves offer the opportunity to evaluate how regional precipitation sourcesand
frequency varied during past warm and cold periods given their geographic position in the first major orographic
barrier to storm tracks coming from the Pacific Ocean. We present a U-Th calibrated set of integrated stable isotope
and trace element proxies for the Last Glacial Maximum through the deglaciation for a stalagmite (ML1) from
McLean’s Cave in the central Sierra Nevada foothills that compliments previously published stalagmite proxy
records from this region (Oster et al., 2009; 2010) and monitoring of a proximal cave (Oster et al., 2012). The U-Th
dates (18,880 ± 270 to 13,520 ± 390) indicate the stalagmite captures abrupt climate shifts including Heinrich Event
1 and the stadials and interstadials of the Bølling-Allerød, particularly the Older Dryas. The U-Th ages indicate
rapid growth rates that permit evaluation of lead-lag relationships between the high latitude northern hemisphere and
mid-latitude records of California that was not possible in earlier stalagmite-based proxy time-series given their
centennial-scale resolution. The oxygen and carbon isotope records for ML1 showsystematic increases during
independently inferred warm periods (interstadials of the Bølling-Allerød) and decreases during cold periods
(Heinrich 1, Older Dryas). Oster et al. (2010; 2012) interpret the Sierra Nevada stalagmite δ18O as dominantly
recording shifts in temperature and precipitation source and δ13C as recording shifts in the degree of prior calcite
precipitation (PCP) and soil respiration. Negativeδ18O excursions during the Heinrich 1 and Older Dryas indicate
decreased temperatures and/or more North Pacific Ocean sourced moisture during these intervals. In addition, we
interpret decreased δ13C during these intervals asdecreased influence of PCP and/or higher soil respiration,
indicating increased moisture conditions above the cave. The ML1 trace element (Mg, Sr, and Ba) concentrations,
analyzed by laser ablation ICP-MS, strongly covary and show promise for future evaluation of the influence of cave
environmental conditions, such as PCP, cave pCO2, and moisture conditions, on stalagmite growth.
Oster, J.L., Montañez, I.P. and Kelley, N.P., 2012. Response of a modern cave system to large seasonal precipitation
variability: Geochimica et Cosmochimica Acta 91, 92-108.
Oster, J. L., Montañez, I.P., Sharp, W. D., and Cooper, K. M., 2009. Late Pleistocene California droughts during
deglaciation and Arctic warming: Earth and Planetary Science Letters 288, 434-443.
Oster, J. L., Montañez, I.P., Guilderson, T. P., Sharp, W. D., and Banner, J. L., 2010. Modeling speleothem
delta(13)C variability in a central Sierra Nevada cave using (14)C and (87)Sr/(86)Sr: Geochimica et Cosmochimica
Acta 74, 5228-5242.
REVISED ∼2000-YEAR CHRONOSTRATIGRAPHY OF PARTIALLY VARVED MARINE SEDIMENT
IN SANTA BARBARA BASIN, CALIFORNIA
Arndt Schimmelmanna, Ingrid L. Hendyb, Larianna Dunnb, Dorothy K. Pakc
a
Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA
Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA cDepartment of Earth
Science, Marine Science Institute, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
b
E-mail address: aschimme@indiana.edu, ihendy@umich.edu, larianna.dunn@gmail.com, pak@geol.ucsb.edu
Sediment in the deep center of the Santa Barbara Basin (SBB) is almost continuously laminated for the past ∼2000
years and has been utilized as an archive for high-resolution paleoceanography since the 1970s. Unequivocal proof
of the presence of varves in SBB sediment throughout the 20th century has been uncritically used to assume that
deeper laminations are varves as well and that they can be counted down-core to arrive at a reliable varve
chronology for the past ~2000 years. The advent of radiocarbon accelerator mass-spectrometric dating of submilligram-sized organic terrigenous plant fragments and charcoal enabled us to independently date SBB sediment
without the underlying uncertainty of variable marine radiocarbon reservoir ages. It was determined that the
traditional SBB varve-count ages remain valid from the present down to ∼AD 1700, whereas not all deeper
laminations represent varves. Depending on depth, the newly revised chronostratigraphy deviates from the
traditional varve-count by up to ~400 years. Evidence from other California offshore locations indicates that the
oxygenation of the deeper water column has been decreasing over the past few hundred years and facilitated a
transition from laminated and possibly intermittently varved sediment to continuously varved sediment in the SBB.
DYNAMIC RESPONSE OF DESERT WETLANDS TO ABRUPT CLIMATE CHANGE
Kathleen Springera, Craig R. Mankera, Jeffrey S. Pigatib, Shannon A. Mahanb
a
b
San Bernardino County Museum, 2024 Orange Tree Lane, Redlands, CA 92374, USA
US Geological Survey, Denver Federal Center, Box 25046, MS-980, Denver, CO 80225, USA
E-mail address: kspringer@sbcm.sbcounty.gov, cmanker@sbcm.sbcounty.gov, jpigati@usgs.gov,
smahan@usgs.gov
Paleoclimate proxy datasets from the American Southwest have established atmospheric teleconnections of past
stadial/interstadial fluctuations with northern hemispheric climatic data. However, the types of records typically
available (pluvial lakes, speleothems, packrat middens) and the general paucity of high-resolution data sets have
limited our understanding of past ecosystem and/or faunal response to rapid climate change. Wetlands in modern
desert environments respond to climatic perturbations. In this study, groundwater discharge deposits (paleowetlands)
were employed as a paleoclimate proxy, and underscore the vulnerability of spring habitats to changes in climate by
documenting the rapid cessation of discharge associated with abrupt climatic warming, and the subsequent collapse
of the wetland environments, repeatedly, over the last glacial period. Within the remarkably continuous, fossilbearing late Pleistocene desert wetland deposits of the upper Las Vegas Wash, in southern Nevada, we have
established the most unique and comprehensive record of groundwater discharge deposits in the world,
demonstrating a tight correlation with Greenland/North Atlantic climate proxy data on a sub-millennial scale. The
nature of hydrologic response is verified both temporally at high resolution for the last 50,000 years as well as
stratigraphically and sedimentologically, by recognition of episodes of groundwater discharge during wet/cool
times, punctuated by abrupt, relatively brief periods of aridity as evidenced by soil formation, desiccation and
erosion associated with warm/dry cycles. This dynamic response bears striking similarly with the established
chronology of the Dansgaard-Oeschger and Heinrich events in the Greenland and North Atlantic ice core and marine
records. Desert wetlands as a hydrologic system can now be utilized to query ecosystem and faunal responses to
abrupt climate change in the past. Further, conservation of modern wetlands, as keystone ecosystems with their high
species biodiversity and endemic biota, should be viewed through this new filter, as they are currently threatened by
anthropogenic warming climes.
BIAS AND SIGNAL DISTORTION IN USING A MODERN POLLEN-CLIMATE CALIBRATION SET TO
INFER A MINNESOTA PRE-EUROPEAN-SETTLEMENT PALEOCLIMATE RECORD
Jeannine-Marie St. Jacquesa, Brian F. Cummingb, D.J. Sauchyna, John P. Smolb
a
b
Prairie Adaptation Research Collaborative, University of Regina, Regina, SK, Canada, S4S 7H9
PEARL Department of Biology, Queen’s University, Kingston, ON, Canada
E-mail address: stjacqje@uregina.ca, sauchyn@uregina.ca
Climate plays a dominant role in controlling a locale’s vegetation; hence, by analyzing pollen spectra preserved in
lake sediments, and interpreting the pollen using a calibration set of paired pollen-climate data, it is possible to
reconstruct a region’s paleoclimate. However, massive human impacts have significantly altered vegetation.
Therefore, the relationship between modern instrumental climate data and the modern pollen rain becomes altered
from what it was in the past. This is of concern because in inferring a paleoclimate record from a sedimentary pollen
record, we rely upon the pollen-climate relationship being constant in time.
In the Midwest, selective logging, fire suppression, deforestation, and agriculture have strongly influenced the
modern pollen rain since Euro-American settlement in the mid-1800s. We assess the signal distortion introduced by
using post-settlement pollen and climate sets to infer climate from pre-settlement pollen spectra. We use a pollen
dataset contemporaneous with early settlement to which corresponding climate data from the earliest instrumental
records has been added to produce a pre-settlement calibration set (the “1870” set) suitable for numerical climate
reconstructions. We also use a corresponding “modern” pollen-climate dataset from core-top pollen samples and
modern climate normals. First, we apply the modern pollen-climate training set to the 1870 pollen data set to
reconstruct the climate at the onset of settlement. These reconstructions are then compared to the contemporaneous
earliest instrumental climate records. Second, we compare and contrast climate reconstructions using both the presettlement and modern pollen-climate calibration sets of a millennium-scale, high-resolution pollen record derived
from varved Lake Mina in central Minnesota and determine which gives a more credible reconstruction as assessed
by the earliest instrumental climate (beginning ~1820) and ice-out records. Both methods show that significant
signal distortion and bias exist when using a modern pollen-climate calibration set rather than a pre-settlement
pollen-climate calibration set, resulting in an overestimation of Little Ice Age temperature.
DEVELOPING 21st CENTURY HYDROCLIMATE SCENARIOS FOR THE BOW RIVER BASIN,
ALBERTA, CANADA
Jeannine-Marie St. Jacquesa, David Sauchyna, David J. Thomsonb, A. Michael S. Sheerc, Daniel P. Sheerc, Michael
Kellyd, Megan van Hamd, Michael W. Nemethd, Elaine Barrowa
a
Prairie Adaptation Research Collaborative, University of Regina, Regina, SK, Canada, S4S 7H9
Department of Mathematics and Statistics, Queen’s University, Kingston, ON, Canada
c
HydroLogics Inc., 10440 Shaker Drive, Suite 104, Columbia, MD 21046, USA
d
WaterSMART Solutions, Ltd., Calgary, AB, Canada
b
E-mail address: stjacqje@uregina.ca, sauchyn@uregina.ca
The Bow River in Alberta, Canada, serves a wide range of municipal, agricultural, recreational, and industrial
purposes. In 2006, the basin was deemed over-allocated and closed to new licenses. In the next 65 years, basin
population levels are expected to double to 2.8 million. This increasing pressure led stakeholders to work together in
the development of a new management model to improve the management of the system as an integrated watershed.
The stakeholders developed the Bow River Operations Model (BROM). Based in OASIS software, this model
integrated input from the major water users in the region to emulate the daily operational decisions.
As part of this project, we modeled Bow River annual streamflow as a function of the ocean-atmosphere
oscillations that drive the natural variability of the regional hydroclimate. The model parameters captured a large
proportion of the variance in the naturalized streamflow, including the low flow years of the 1930s and the high flow
years of the 1940s and 1950s. We then drove the generalized-least-squares regression models of annual streamflow
using projected 21st century output from an ensemble of Coupled Model Intercomparison Project Phase 3 (CMIP3)
global climate models that simulated the relevant teleconnection patterns (i.e., ENSO and PDO). Future climate was
externally forced by rising greenhouse gases, according to the A2, A1B, and B1 SRES scenarios. The outputs from
many simulations were re-sampled, generating sufficient data for the construction of cumulative distribution
functions (CDFs), from which the probability of exceeding critical values for hydrologic parameters was
determined. Projected daily streamflows were generated from the annual flows by analog matching to historical
daily flows using the QPPQ (streamflow-probability-probability-streamflow) transform. The scaled projected daily
flows then served as inputs into the BROM to produce plausible projected flow and demand scenarios to guide
policy decisions.
CLOSED LAKE OXYGEN ISOTOPE RECORDS OF DROUGHT IN THE PACIFIC NORTHWEST
SPANNING THE COMMON ERA
Byron A. Steinmana, Mark B. Abbottb, Michael E. Manna, Joseph D. Ortizc, Lesleigh Andersond, Bruce P. Finneye,
David P. Pompeanib
a
Department of Meteorology and Earth and Environmental Systems Institute, The Pennsylvania State University,
University Park, PA 16802-5013, USA
b
Department of Geology and Planetary Science, University of Pittsburgh, 4107 O'Hara Street, SRCC Room 200,
Pittsburgh, PA 15260-3332, USA
c
Department of Geology, Kent State University, Kent, OH 44242, USA
d
US Geological Survey, DFC Box 25046, MS-980, Denver CO 80225, USA
e
Departments of Geoscience and Biological Science, Idaho State University, 921 South 8th Avenue, STOP
8072,
Pocatello, ID 83209-8072, USA
E-mail address: bas56@psu.edu
During the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) the tropical Pacific Ocean was likely
characterized by a La Niña- and El Niño-like mean state, respectively, which produced shifts in North American
hydroclimatic conditions that have no historical precedent. Here we synthesize oxygen isotope records from nine
lakes in the southern Yukon, central British Columbia, and the northwestern United States indicating that the LIA
was a time of exceptional dryness and that the MCA was relatively wetter. We compare the lake sediment isotope
data to synoptic paleoocean-atmosphere proxy datasets, records of external forcing (i.e., solar and volcanic), and
tree-ring based Palmer Drought Severity Index (PDSI) reconstructions that span the last 1000-2000 years to
ascertain the influence of climate system responses to external forcing on precipitation-evaporation balance in
western North America. Proxy data from the American southwest (including tree rings and speleothems) document
connections between inferred solar activity maxima, La Niña like conditions in the tropical Pacific and reduced
water availability in the American southwest. Lake sediment δ18O data from the Pacific Northwest reveal an
opposite century timescale pattern in which periods of reduced solar activity correspond with dryness, and vice
versa, similar to the observed, north-south antiphasing pattern of drought linked to ENSO dynamics. To investigate
potential differences between the lake sediment δ18O and tree-ring data, we applied a 25-year low pass filter and
standardized the datasets. Five of the seven lake records located in regions with PDSI reconstructions that span the
last ~1500 years are consistent with the tree-ring proxy data (indicating a drier LIA and a wetter MCA). However,
the magnitude of century timescale shifts in the standardized lake datasets is larger than that documented by the treering records of drought. It is therefore possible that larger magnitude centennial shifts in hydroclimate than deduced
from the tree-ring proxy data alone may have occurred over the last 2000 years, and that the climate system of the
American west is more sensitive to changes in radiative forcing than previously thought.
CHANGING LIKELIHOODS OF EXTREMELY LOW FLOWS, HIGH FLOWS, AND HIGH STREAM
TEMPERATURES IN THE SIERRA NEVADA, CALIFORNIA
Iris T. Stewarta, Darren L. Ficklina,b, Edwin P. Maurerc, Russell Mcintosha, Carlos Carrilloa
a
Department of Environmental Studies and Science, Santa Clara University, Santa Clara, CA, 95053, USA
Department of Geography, Indiana University, Bloomington, IN 47405, USA
c
Department of Civil Engineering, Santa Clara University, Santa Clara, CA 95053, USA
b
E-mail address: IStewartFrey@scu.edu
The increasingly warmer temperatures and changes in precipitation patterns expected from climatic changes in the
Sierra Nevada are projected to drive declines in snowpack, earlier streamflow timing, shifts in evapotranspiration
and soil moisture, and substantial increases in summer stream temperatures with associated declines in water quality.
Here we examine if these climatic and hydrologic changes are likely to change the occurrence of extremes. Output
from an ensemble of 16 General Circulation Model (GCM) projections was used for two emission scenarios to drive
the Soil and Water Assessment Tool (SWAT), with a new integrated stream temperature model. The resulting flow
and temperature output for the 2070-2099 period was compared to that of the historic period in terms of the
occurrence of a) seasonal high flows, defined as 125 and 150% of historic seasonal averages, b) seasonal low flows,
defines as 75, 50 and 25% of historic seasonal averages, and c) stream temperature extremes. Results indicate that
by the end of the century, high flows are more likely during the winter season throughout much of the Sierra
Nevada, especially the headwaters, while the likelihood for low flows increases for future spring seasons, and
dramatically increases with future summer seasons. The extremely low flows are connected to substantially higher
stream temperatures and declines in water quality with potential ecologic consequences.
AN ORGANIC GEOCHEMICAL RECORD OF THE LAST INTERGLACIAL-GLACIAL TRANSITION
FROM THE HIGH ELEVATION COLORADO ROCKY MOUNTAINS
Joseph H. Streeta, Pratigya J. Polissarb, Adina Paytanc
a
Department of Earth & Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
Division of Biology and Paleo Environment, LDEO of Columbia University, Palisades, NY 10964, USA
c
Institute of Marine Sciences, University of California, Santa Cruz, CA 95064, USA
b
E-mail address: jstreet@stanford.edu, polissar@ldeo.columbia.edu, apaytan@ucsc.edu
Hydrologic variability in the American Southwest is a function ofseasonal precipitation patterns, linked to North
Pacific winter storm activity and the North American summer monsoon. Previous paleoclimatic studies offer
evidence of regional precipitation responses to changing insolation, ice sheet dynamics, and ocean circulation, but it
has been difficult to differentiate the seasonal signals. The recent discovery of a lacustrine sediment sequence
spanning ~130,000-50,000 years at Ziegler Reservoir, near Snowmass, Colorado, offers a rare opportunity to
reconstruct high-elevation continental climate and test large-scale teleconnections during the Sangamon interglacial
(MIS 5e) and the transition into MIS 4. Our work uses organic geochemical and isotopic proxies (C/N, δ13C, δ15N,
biomarkers) to reconstruct changes in vegetation, biogeochemical cycling and lake level at the site. We are also
examining the hydrogen isotopic composition (δD) of plant-waxes as potential paleohydrologic proxies. At this site,
long-chain, terrestrial leaf-wax n-alkanes primarily record δDprecipitation, which is influenced by the moisture sources,
vapor history, and seasonality of precipitation. The δD of short-chain, macrophyte-derived n-alkanes, in contrast, is
also sensitive to the local precipitation-evaporation balance. Using these source-specific isotopic signals, we will
attempt to reconstruct both local aridity and the relative importance of winter (North Pacific) vs. summer (local
convection, NAM) precipitation in the central Rockies across the MIS 5 –4 transition. Early results indicate that
large changes in the lake environment occurring over the ~80,000-year record. A long-term decline in the relative
abundance of terrestrial plant n-alkanes in favor of macrophyte-derived compounds, along with an increase in the
δD of the aquatic n-alkanes, suggests a transition from high lake levels and open-water conditions to a shallowwater marsh/bog environment. Interestingly, the δD of terrestrial n-alkanes declined over the full record. Taken
together, the available evidence suggests relatively wet conditions in the high-elevation Rockies during the last
interglacial, supported by mixed summer and winter precipitation. Progressive drying moving into MIS 4 may have
been related to reductions in summer precipitation.
A RECORD OF LATE HOLOCENE PALEOMEGAFLOODS FROM LITTLE PACKER LAKE AND
RAZOR SLOUGH, SACRAMENTO VALLEY OXBOW LAKES
Donald G. Sullivana, Roger Byrneb, Alicia Cowartb, Susan Zimmermanc
a
Department of Geography and the Environment, University of Denver, Denver, CO 80208, USA
Department of Geography, University of California, Berkeley, CA 94720, USA
c
CAMS, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
b
E-mail address: dsulliva@du.edu, arbyrne@berkeley.edu; alicia@berkeley.edu, zimmerman17@llnl.gov
A convergence of recently reported studies shows that California has been subject to periodic megafloods over the
last two millennia. In this paper we show how oxbow lakes in the Sacramento Valley have preserved a sedimentary
record of these flood events. More specifically, we report on sediment stratigraphy of cores recovered from Little
Packer Lake and Razor Slough, two oxbow lakes in Glenn County, California. We developed an age model for the
cores with AMS radiocarbon dating and the first appearances of non-native pollen types. The chronology indicates
that Little Packer Lake formed as a cut-off oxbow around 800 years ago and Razor Slough shortly afterwards. The
mean sedimentation rate for both lakes is about 1 mm/yr. Also, cores from both lakes show basically the same
sequence of major flood events. The flood signal consists primarily of increases in sediment density and magnetic
susceptibility. Flood deposits appear as dense layers on x-radiographs and are especially well defined in upper
sections of the cores. In the lower sections the density differences are less obvious, probably because of compaction
and mineralization of organic matter. Fortunately, the flood signal is well preserved in the magnetic properties of the
sediments and the flood events show up clearly as peaks in the magnetic susceptibility record. The difference
between flood deposits and non-flood deposits is also apparent in differences in organic content, particle size,
sediment chemistry (as determined by XRF) and bulk density determinations. As a check on our assumption that
these differences in sediment properties are indeed the result of flooding, we compared our paleoflood record with
the known history of major floods in the Sacramento Valley over the past 200 years. Reassuringly, the two records
are very similar. There is also support for some of the earlier flood events insofar as their timing is close to that
reported for other prehistoric floods in the Central Valley of California. One important implication of this study is
that the oxbow lake sediments can provide reliable records of prehistoric flooding. The two lake records reported on
here cover the last 800 years; a more extensive coring effort in the same area could extend the record back several
thousand years.
CORRELATION OF CLIMATE RECORDS BETWEEN A GREAT BASIN LAKE AND A GREENLAND
ICE CORE DURING THE MONO LAKE EXCURSION
Gregory Richard Thompsona, Lindsey D. Medinaa, Martin Matthew Jimeneza, Esteban Maciasa, Cristina Rivasa, Rob
Negrinia, Manuel R. Palacios-Festb
a
Department of Geological Sciences, California State University, Bakersfield, CA 93311, USA
Micropaleontology and Paleoecology Specialists on Environmental Change Analysis, Terra Nostra Earth Sciences
Research, Tuscon, AZ 85740, USA
b
Email address: greg.thompsn@gmail.com
A high-resolution record of lake conditions at Summer Lake, Oregon, between ~37,000 and 32,000 years has been
obtained using ostracode analysis from the BB3-I core, taken in the Fall of 2010. The ~37,000-32,000 year time
period in the BB3-I core contains the Mono Lake geomagnetic excursion including a record of extremely low
magnetic field intensity during this event. Low magnetic field intensity has also been observed in the GRIP
Greenland ice coreat the same time based on high concentration of cosmogenic isotopes. At the same time, oxygen
isotopes in the GRIP core suggest extremely cold temperatures in the North Atlantic region between Interstade #7
and #6 of the Dansgaard/Oeschger millennial-scale climate oscillations. To test the influence of these extremely cold
North Atlantic temperatures on lake conditions in western North America, we counted the concentration of
ostracode species in the BB3-I core within and outside of the interval of low paleointensity during the Mono Lake
excursion. Ostracodes can be very sensitive to changes in both temperature and salinity and are effective indicators
of paleoclimate in closed basins such as Summer Lake. Notably, Cytherissa lacustris, an ostracode with affinities
for Arctic conditions, was observed in the BB3-I core in the low paleointensity interval of the Mono Lake excursion
suggesting strongly that the Great Basin experienced very low temperatures at the same time as did the North
Atlantic. Furthermore, alternating presence and absence of this ostracode down core reveals the same warm/cold
climate oscillations as the GRIP core down to an unconformity in the BB3-I associated with a drought during the
extremely cold, dry climate interval throughout the Great Basin that was probably due to the Heinrich 4 interval of
extremely cold climate.This conclusion will be tested using other indicators of paleolake conditions including grain
size, total organic and inorganic carbon, and carbon/nitrogen ratios.
A 10,500 YEAR RECORD OF VEGETATION AND FIRE HISTORY FROM LOWER WHITSHED LAKE
NEAR CORDOVA, ALASKA
Martina T. Tingleya, R. Scott Andersona,b, Darrell Kaufmanb, Megan Arnoldb
a
Bilby Research Center, Northern Arizona University, Flagstaff, AZ 86011, USA
School of Earth Sciences and Environmental Sustainability, Northern Arizona University, Flagstaff, AZ 86011,
USA
b
E-mail address: mtt26@nau.edu, Scott.Anderson@nau.edu, Darrell.Kaufman@nau.edu, Megan.Arnold@nau.edu
Lower Whitshed Lake is a small, coastal lake on the tectonically active eastern margin of Prince William Sound,
near Cordova, Alaska. Coastal spruce-hemlock forest, with Picea sitchensis, Tsuga mertensiana, and T.
heterophylla, currently dominates the site in a region where summers are cool and cloudy, winters are mild and
precipitation is high. Few sites in this forest type have been investigated for their long-term histories, and the Lower
Whitshed record is important in determining (1) the biogeography of coastal conifers and (2) the long-term history
of fire for this vegetation type. It provides a continuum between sites in southeastern Alaska and those to the west on
the Kenai Peninsula. We use a multi-proxy approach, including stratigraphies of pollen, charcoal particles, total
organic-matter (TOC), and biogenic silica (BSi) to determine a centennial-scale view of long-term environmental
change for the site for the last ca. 10,500 calendar years. Holocene sediments consist primarily of gyttja. Subsequent
to deglaciation pollen evidence suggests a dwarf shrub-tundra (dwarf Betula, Salix, Ericaceae, with Artemisia and
Poaceae) existed around the lake until ca. 10,100 cal yr BP. Sediments were low in TOC but with relatively high
BSi. A woodland of Alnus became established by 10,100 cal BP and dominated with little change until ca. 3500 cal
BP. Sediment TOC increased during this period and modest values of BSi indicate a moderately productive lake.
Finally, conifer forest dominated the site with rapid and successive immigrations of Picea sitchensis (ca. 3500 cal yr
BP), P. mariana, and T. mertensiana (ca. 3000 cal yr BP). The arrival of T. heterophylla at ca. 2000 cal yr BP
signifies development of the modern forest. Sedimentary charcoal is not abundant in this record. However, charcoal
abundance increases at the transition from the shrub-tundra to dominance by Alnus woodland. Additional charcoal
analyses are ongoing.
A HOLOCENE RECORD OF LARGE-SCALE DISTURBANCE EVENTS IN THE UINTA MOUNTAINS,
UTAH, USA
Lovina A. Turney, Mitchell J. Power
Department of Geography, University of Utah, Salt Lake City, UT 84112, USA
E-mail address: lovina.turney@utah.edu
Holocene climate variability has resulted in a dynamic disturbance history in the Uinta Mountains. A 12,000-yearlong lake sediment record provides evidence of large magnitude fire and flood events during the Holocene. The
frequency of fire increased during the middle to late Holocene transition (~3000 cal yr BP), but then decreased in
the last millennia. As fire frequency decreased the magnitude of fire and flood events have increased. The
importance of large magnitude flood events is also explored in terms of frequency and magnitude. The recent (20th
century) catastrophic draining of this montane lake that was dammed by a recessional moraine provides a recent
example of an extreme disturbance event. The study site today, currently being colonized by lodgepole pine, affords
a unique opportunity with excellent preservation of fossil pollen and paleobotanical remains to explore the
magnitude and frequency of disturbance in this setting. Results from the fossil charcoal, pollen and lithologic
analyses are compared with centennial-scale late Holocene climate records to evaluate the influence of climate ion
disturbance, including the Medieval Climate Anomaly and Little Ice Age. These findings provide context for
understanding recent large magnitude disturbance events in the Uinta Mountains.
DON’T WORRY ABOUT CLIMATE CHANGE; CALIFORNIA’S NATURAL CLIMATE VARIABILITY
WILL PROBABLY “GET US” FIRST
Kenneth L. Verosub
Department of Geology, University of California, Davis, CA, 95616, USA
E-mail address: klverosub@ucdavis.edu
California moves more water than any other political entity in the world, and it uses a lot of energy to do it. A
growing population and growing demand for water, coupled with geotechnical and environmental threats to the
Sacramento-San Joaquin Delta, the lynchpin of California’s water delivery system, are causing Californians to make
difficult decisions with regard to maintaining current supplies and developing new ones. Overlaid on these issues is
the threat of reduced water flows resulting from climate change, particularly for the Colorado River basin and the
Owens Valley/Mono Lake system. What is often missing from the discussion about various alternatives is
consideration of the natural climate variability in California over the past 10,000 years and particularly the past 1000
years. For example, river flow and lake level measurements from the twentieth century document the occurrence of
several multi-year droughts in the past 100 years while tree ring records show that 20-year and 70-year droughts
occurred during the last 300 years. On an even longer time scale, at least once and probably several times in the last
few thousand years, there have been droughts severe enough to drop the level of Lake Tahoe by several tens of
meters, which allowed Douglas fir trees to grow to maturity on exposed lake beds. Conversely, new information
about the 1861-1862 water year, during which there was extensive flooding in the Sacramento Valley, suggests that
the entire weather system of the West Coast “flipped” into a different mode that brought heavy rains and flooding all
the way from northern Oregon to southern California. Thus, the paleoclimate history of California suggests that even
in the absence of climate change due to anthropogenic greenhouse gases, decadal, multi-decadal or even centurylong droughts are a real possibility in the future for California as is flooding on a greater scale than was seen in the
twentieth century. A decade-long drought would wreck havoc with California’s delicately balanced water delivery
system, and a repeat of the 1861-1862 precipitation regime could bring enough water into the Delta to overwhelm
the levee system and destroy California’s ability to transfer water from north-to-south.
A 7700 YEAR RECORD OF PALEOENVIRONMENTAL CHANGE FROM FAVRE LAKE, RUBY
MOUNTAINS, NEVADA
David Wahl, Scott Starratt, Lysanna Anderson, Jennifer Kusler, Christopher Fuller, Elmira Wan, Holly Olson
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94720, USA
E-mail address: dwahl@usgs.gov
Few records of Holocene climate variability have been generated from high elevations in the Great Basin. By
combining a broad suite of proxy data (pollen, diatom, charcoal, biogenic silica, magnetic susceptibility, loss-onignition, density, and grain-size), this study evaluates changes in watershed vegetation, lake levels, and limnological
conditions in order to understand millennial and centennial-scale changes in regional climate. Here we report data
from a 4.2-meter-long sediment core collected from Favre Lake (2899 masl; 12 m deep; 7.7 hectares) in the northern
Ruby Mountains. Age control is provided by the Mazama ash, six14C AMS determinations, and 210Pb dating; an agedepth model was created using the CLAM program, which indicates an average sedimentation rate of 0.524
mm/year that extends to ~7700 cal yr BP. Pinus and Artemisia dominate the pollen record, followed by subordinate
levels of Poaceae, Asteraceae, Amaranthaceae, and Sarcobatus. Biogenic silica results suggest fluctuating
productivity from 7300-5750, followed by decreased variability. Between about 7700 and 6000 cal yr BP, the
diatom flora is dominated by a diverse assemblage of benthic species. The remainder of the core is dominated
by Fragilaria which suggests a rising lake level after 6000 cal yr BP, possibly a result of flooding a shallow shelf
that surrounds the depocenter of the lake. This interpretation is supported by coeval increases in percentages of
several aquatic plant taxa (Isoetes, Typha, and Pediastrum) around 5750 cal yr BP. Macroscopic charcoal influx
increases at this time as well, suggesting an increase in fuel availability or ignition sources. Planktonic diatom taxa
(Cyclotella, Asterionella, Tabellaria) increase in abundance during the last 500 years of the record. This change in
the assemblage may indicate modern conditions in which the lake drains into Kleckner Creek to the west.
PRELIMINARY POLLEN RECORD FROM ECHO LAKE, RUBY MOUNTAINS, NEVADA
James A. Wanketa, David B. Wahlb, Jennifer E. Kuslerb
a
b
Department of Geography, Sacramento State University, Sacramento, CA 95819, USA
US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
E-mail address: jwanket@csus.edu
A 60-cm-long sediment core from Echo Lake, a 45 m deep cirque lake in the Ruby Mountains of Nevada, provided
a record of pollen and spanning the last several hundred years. Age control was provided by a combination of annual
layering, 210Pb, and radiocarbon. The results of these analyses indicate that although limber pine, whitebark pine,
and Great Basin sagebrush (the dominant plant species in the alpine areas of the Ruby Mountains today) have been
important throughout the last several hundred years, some alpine species have been reduced in range or extirpated
from the mountains during this time frame. Pollen of mountain hemlock and white fir are present in sediments
deposited early in the period but not in more recent sediments. Today, white fir is found in only one isolated stand in
the Ruby Mountains, while mountain hemlock is not found in the mountains of the Great Basin outside of the
eastern Sierra Nevada. It is likely that other alpine species not well-represented in the pollen record were also
reduced in range or extirpated along with white fir and mountain hemlock. It is likely that changes in temperature,
snowpack, and/or fire frequency over the time frame represented by the sediment record drove changes in alpine
species composition in the Ruby Mountains.
STOCHASTIC ANALYSIS OF MULTI-YEAR RUNOFF, RECHARGE, AND CLIMATIC WATER DEFICIT IN
GEOLOGICALLY VARYING WATERSHEDS
Stuart B. Weiss
Creekside Center for Earth Observation, 27 Bishop Lane, Menlo Park, CA 94025, USA
E-mail address: stu@creeksidescience.com
Numerous climate futures are now available from downscaled global climate models. The translation of monthly
precipitation and temperatures into hydrologically and ecologically meaningful outputs for managers and planners is
the next frontier. The Basin Characterization Model (BCM) is used to generate time series of annual runoff,
recharge, and climatic water deficit (CWD) at the scale of small planning watersheds in the San Francisco Bay Area.
These watersheds differ in climate, soils, bedrock permeability, and human use. A basic water balance diagram
provides a monthly view of hydrology for multi-year averages and individual years. Frequency and intensity of
droughts in historical and projected climate time-series are calculated, and metrics based on multi-year running
averages are developed. Projected droughts are compared with historical droughts (1976-1977, 1987-1992, and
2007-2009), providing analogs and benchmarks within recent experience. Bedrock permeability affects runoff to
recharge ratios, and soil moisture capacity produces fine-scale variability in storage and CWD. Rising temperatures
drive higher potential evapotranspiration, which increases CWD even with greater average annual precipitation,
leading to greater stress on terrestrial and aquatic ecosystems. Quantifying probabilities of drought stress by using
time series and quantile analysis of CWD, runoff, and recharge defines risks at fine spatial scales relevant to water
and land managers, and can be incorporated into existing water supply and flood management frameworks.
ATMOSPHERIC PRESSURE VARIABILITY OVER WESTERN NORTH AMERICA AND THE NORTH
PACIFIC RECONSTRUCTED USING TREE-RING RECORDS
Erika K. Wise, Matthew P. Dannenberg
Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
E-mail address: ekwise@email.unc.edu
Changes in moisture delivery to the West are largely controlled by interrelated, synoptic-scale atmospheric features,
such as the strength and position of the Pacific sub-tropical high and the Aleutian low. Long-term records of these
pressure patterns and associated atmospheric circulation are needed to understand the drivers of persistent droughts
recorded in the paleoclimate record and to evaluate how climate changes may impact hydroclimatic systems in the
future. In this study, we utilized 500hPa geopotential height (GPH) data from the 20th century Reanalysis (V2)
project and existing tree-ring chronologies from the International Tree-Ring Data Bank to reconstruct a multicentury record of year-to-year variation in atmospheric pressure patterns. We tested four Climate Field
Reconstruction methods that have been commonly utilized in paleoclimate studies: Canonical Correlation Analysis
(CCA), Regularized Expectation Maximization with ridge regression (RegEM-ridge), Regularized Expectation
Maximization with Truncated Total Least Squares regression (RegEM-TTLS), and Point-by-Point Regression
(PPR). We found that each method produced similar spatial patterns of error, but that the RegEM-ridge method
produced the most robust reconstruction of GPH based on calibration and validation statistics. The RegEM-ridge
method was used to produce a 2 x 2 degree gridded reconstruction of 500hPa GPH over western North America and
the northeastern Pacific Ocean. This reconstruction of GPH rivals the robustness of tree-ring based temperature and
precipitation reconstructions, although there is uneven performance over the spatial grid. The reconstructed
atmospheric pressure record allows characterization of the frequency of certain circulation patterns, their variability
through time, and their impact on hydroclimatic conditions.
INFLUENCE OF NORTHERN HEMISPHERE TELECONNECTIONS ON ENSO-RELATED
PRECIPITATION PATTERNS IN THE UNITED STATES
Melissa Wrzesiena, Erika K. Wiseb
a
Curriculum for the Environment and Ecology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,
USA
b
Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
E-mail address: wrzesien@live.unc.edu, ekwise@email.unc.edu
Ocean−atmosphere oscillations like the El Niño−Southern Oscillation (ENSO) system have far-reaching effects on
regional climate in teleconnected regions. Climate forecasts often consider ENSO when predicting regional climate
for the United States. However, there are numerous other climate systems influencing temperature and precipitation
patterns at any time, and incorporating the effects of other teleconnections (North American Oscillation, East
Atlantic, Pacific-North American, etc.) could help improve the reliability of shorter-term forecasts. We correlated
the teleconnection indices with gridded precipitation data from the Parameter-elevation Regressions on Independent
Slopes Model (PRISM) data set and found statistically significant patterns across the United States when
considering each pattern separately. We also considered the interactions between these oscillations by examining
how the precipitation impact pattern during different ENSO phases varied by phase of other atmospheric
teleconnections. We found that there is great variability in the ENSO regional impact pattern related to its
interactions with Northern Hemisphere teleconnections. Incorporating this additional information into climate
forecastswould likely improve regional,short-term forecasts.
CENTRAL-PACIFIC EL NIÑO: DYNAMICS, CLIMATE IMPACTS, AND THE CAUSE OF ITS RECENT
EMERGENCE
Jin-Yi Yu
Department of Earth System Science, University of California, Irvine, CA 92697, USA
E-mail address: jyyu@uci.edu
The recent identification of two distinct types (or flavors) of El Niño offers a new way to reconsider how El Niño
and its global impacts may change as the climate changes. These two El Niño types are the Eastern Pacific (EP) type
that produces sea surface temperature (SST) anomalies near the South American coast and the Central Pacific (CP)
type that produces anomalies near the international dateline. While the EP El Niño used to be the most frequently
occurring type of El Niño, it has come to people's attention that the CP El Niño has gradually increased in
occurrence over the past two decades. The intensity of El Niño in the CP region has doubled in the past decades.
Three of the four El Niño events in the 21st century (the 2002/03, 2004/05, and 2009/10 events) have been of the CP
type. The CMIP5 models project that the CP type may become more prevailing in a future warmer world. These
studies indicate that the CP El Niño is an emerging mode of climate variability.
More importantly, recent studies suggested that the generation mechanism of the CP El Niño is different from
that of the EP El Niño. The CP El Niño was argued to result not from basin-wide interactions between the tropical
Pacific Ocean and the Walker circulation, which is the generation mechanism for the EP El Niño. Rather, the CP El
Niño was suggested to grow via interactions between the tropical Pacific and the Hadley circulation. CP El Niño
events are excited by extratropical atmospheric forcing (via the lower returning branch of the Hadley circulation)
and then intensify in the central equatorial Pacific via local air-sea interactions. The connection with the Hadley
circulation implies that the CP El Niño may produce a stronger impact on higher-latitude climate than the EP El
Niño. A record warming in the South Central Pacific and western Antarctica were observed during the strong CP El
Niño in 2009. Several recent studies have also indicated that the CP El Niño can affect global climate differently
from the EP El Niño. These studies suggest that we cannot use our existing understanding of the conventional EP El
Niño to anticipate the climate impacts and teleconnections associated with the CP El Niño. A better understanding
of the emerging CP El Niño is important to climate change studies.
In this talk, statistical analyses, forced and coupled model experiments, and case studies will be presented to
discuss the (1) the role of extratropical forcing in the generation of the CP El Niño; (2) the changing impact of the El
Niño on US winter climate after the El Niño shits from the EP type to the CP type, and (3) the possible cause of the
increased occurrence of the CP El Niño after 1990.
HOLOCENE HISTORY OF MONO LAKE, CALIFORNIA, USA, FROM MULTIPLE SEDIMENT CORES
Susan R. Zimmermana, Scott W. Starrattb, Sidney R. Hemmingc
a
CAMS, Lawrence Livermore National Lab, Livermore CA 94550, USA
US Geological Survey, 345 Middlefield Road, Menlo Park, CA, 94025, USA
c
Lamont-Doherty Earth Observatory and Dept. of Earth and Environmental Sciences, Columbia University, New
York, NY 10027, USA
b
E-mail address: zimmerman17@llnl.gov
Mono Lake is a closed-basin lake in the eastern Sierra Nevada, and modern water supply to the lake is dominated by
spring run-off from the mountain snowpack. Changes in lake level over the last ~2000 years are well documented
(Stine, 1990), due to exposure of geomorphic and sedimentary evidence by artificial lake-level lowering over the
last ~70 years. Newly acquired cores from water depths of 2 to 34 m provide a record of sedimentation in Mono
Lake over the last hundreds to thousands of years. In this study we assess the record of sedimentological, chemical,
and biological changes wrought by the lake level changes defined by the geomorphic record. Radiocarbon dates and
tephrostratigraphy show that the longest core, BINGO-4A-1N, records all of the Holocene, in variable proportions
of detrital, volcanic, and authigenic sediment. The early Holocene portion of the core (10,660-7500 cal yr BP) is
characterized by finely laminated olive mud that we infer to imply relatively stable, deep lake conditions. These
laminated sediments grade into units with more variable amounts of authigenic carbonate in the middle and late
Holocene. Both the 1300-year and 600-year old tephras (Bursik and Sieh, 2011) are present in the upper 60 cm, and
minor hiatuses are likely near the top of the core due to the proximity of the core site to the medieval and historical
shorelines. A thick, coarse sand at the top of the BINGO-4A-1N core is also found at the tops of two additional
cores from similar water depth (<3 m in 2009), but below this interval these cores contain tens of centimeters of
well-bedded to laminated organic-rich mud. Cores from 17 m and 34 m water depth lack the coarse top unit and
show ≥ 50 cm of laminated mud, potentially preserving an annual to multi-annual record of lake conditions over the
last centuries.
Bursik, M.I. and Sieh, K., 2011. Holocene eruptions of the Mono-Inyo craters, California: Geological Society of
America, Abstracts with Programs 43(5), 510.
Stine, S., 1990. Late Holocene fluctuations of Mono Lake, eastern California: Palaeogeography, Palaeoclimatology,
Palaeoecology 78, 333-381.