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001 AAI3427086
005 20110915090253.5
008 110915s2010 ||||||||s|||||||| ||eng d
020 9781124304038
035 (UMI)AAI3427086
040 UMI|cUMI
100 1 Roach, Lydia Darcy
245 10 Climate Change in the Pacific North America Region Over
the Past Millennium: Development and Application of Novel
Geochemical Tracers|h[electronic resource]
300 255 p
500 Source: Dissertation Abstracts International, Volume: 72-
01, Section: B, page: 0158
500 Advisers: Christoper D. Charles; Daniel R. Cayan
502 Thesis (Ph.D.)--University of California, San Diego, 2010
520 Decadal climate variability in the Pacific North America
(PNA) region largely determines the fresh-water supply of
the western United States and fisheries production of the
northeast Pacific Ocean through tightly coupled ocean-
atmosphere interactions. Documenting the historical
manifestations of these interactions, over at least the
past millennium, is an essential step towards anticipating
the ramifications of future climate change on these
resources. This dissertation aims to extend efforts at PNA
paleoclimate reconstruction through the development of
interannually resolved geochemical proxy records from
annually laminated marine and lacustrine sediments.
Comparison with instrumental climate measurements provides
constraint on the driving mechanisms for observed
geochemical variability in each record. The radiocarbon
content (Delta 14C) of benthic foraminiferal tests in the
Santa Barbara Basin (SBB) proves a sensitive tracer for
decadal fluctuations in vertical density structure along
the southern California margin that are forced by north
Pacific ocean-atmosphere interactions and tropical-
midlatitude teleconnections. Enumeration of cosmopolitan
benthic foraminifera in the SBB over the past ∼250
years suggests that, on decadal time scales, the overall
size and distribution of the SBB benthic foraminiferal
community is largely a function of benthic carbon
oxidation rate---a property previously linked to regional
surface productivity. In the terrestrial realm, stable
hydrogen isotope ratios (deltaD) of plant lipid biomarkers
preserved in the sediments of Swamp Lake, Yosemite
National Park, were measured over the 20th century and
late medieval period (1160-1432 A.D). Plant lipid deltaD
exhibits a complex relationship with environmental
parameters but nevertheless reflects interannual to
multidecadal changes in amount of wintertime precipitation
in the Sierra Nevada Mountains over the 20th century.
Consistent with this observation, multidecadal deltaD
variability during the late medieval generally follows
that of concomitant tree ring-derived hydrologic
reconstructions and captures droughts of greater severity
than any witnessed in the Sierra Nevada over the past 100
years. Comparison of the two isotopic records in terms of
medieval vs. modern drought severity, however, requires
further constraint on the driving mechanisms for long-term
shifts in plant lipid deltaD. Overall, this dissertation
documents the novel application of benthic foraminiferal
Delta14 C and plant lipid deltaD as a means for
reconstructing decadal scale PNA climate from high-
resolution sedimentary archives
590 School code: 0033
650 4 Climate Change
650 4 Paleoclimate Science
650 4 Environmental Sciences
650 4 Geochemistry
690 0404
690 0653
690 0768
690 0996
710 2 University of California, San Diego.|bOceanography
773 0 |tDissertation Abstracts International|g72-01B
856 40 |uhttps://pqdd.sinica.edu.tw/twdaoapp/servlet/
advanced?query=3427086
912 PQDT
