Scott, Wesley
(2022)
Modern Day and Common Era Climate in Northern Patagonia: A reconstruction using novel organic geochemical proxies.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The present-day hydroclimate on the western side of southern South America is dominated by the Southern Westerly Winds (SWW). The SWW are the strongest time-averaged winds on Earth and are related to significant global climatic features, such as the Antarctic circumpolar current and Pacific Ocean surface dynamics. Additionally, when the SWW are shifted poleward and are more intense, there is increased upwelling from the deep ocean, and this can degas enough CO2 to affect global atmospheric CO2 concentration. Anthropogenic warming across the globe is expected to alter the seasonal position and strength of the SWW, which is directly correlated to the amount of regional precipitation in Chile, but the magnitude of these expected changes is uncertain. Chile is projected to become significantly warmer and drier over the next several decades as the SWW shift southward. Since 2010, central Chile has experienced what has been called a “mega-drought” which has significantly altered the frequency of regional forest fires and decreased water availability1. To better understand the SWW-driven paleoclimate in southern Chile, it is necessary to investigate current regional features such as modern climatic and physical conditions as a prelude to mapping out the history of past significant climate events, such as periods of drought, throughout the past 2000 years. To establish a modern baseline, we analyzed the isotopic composition of lake surface waters and organic biomarkers (leaf wax lipids and bacterial derived membrane lipids, brGDGTs) extracted from surface sediments of over 50 lakes in Chile and determined the validity of the application of these biomarkers for down-core paleoclimate applications. To move into the past, we then applied the biomarker proxies down-core in Lago Frio, Chilean Patagonia, in order to reconstruct paleotemperatures and hydroclimate. We find that temperature and rainfall fluctuated significantly over the past 2000 years, including shifts that are simultaneous with well-established Northern Hemisphere climate events such as the Medieval Climate Anomaly (MCA).
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
13 August 2022 |
| Date Type: |
Publication |
| Defense Date: |
26 April 2022 |
| Approval Date: |
18 December 2024 |
| Submission Date: |
3 August 2022 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
106 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Geology and Environmental Science |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Paleoclimate, Patagonia, stable isotopes, organic geochemistry |
| Date Deposited: |
18 Dec 2024 20:11 |
| Last Modified: |
19 Dec 2024 13:09 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/43629 |
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