Common Era Midcontinental Hydroclimate Variability Inferred from Iowan Lake Sediments, Usa

Date
2024-02
Language
American English
Embargo Lift Date
Department
Committee Chair
Degree
M.S.
Degree Year
2024
Department
Department of Earth Science
Grantor
Indiana University
Journal Title
Journal ISSN
Volume Title
Found At
Abstract

Global climate change manifests diverse consequences across the United States, creating distinct challenges in different regions. For example: The Western United States grapples with a notable surge in wildfires and drought events, indicating reduced effective moisture. In contrast, the Eastern part faces severe and frequent flooding events, reflecting higher effective moisture conditions and suggesting an East-West dipole-like climatic pattern. While the current East-West dividing hinge-line sits at 96°W, questions linger about its persistence throughout the late Holocene or whether it has undergone changes over time. Understanding the evolution and stability of this hinge-line is crucial for predicting the impacts of ongoing global warming on various U.S. regions. To address this issue, it is essential to develop additional paleoclimate records from the U.S. Midcontinent, especially those in close proximity to the modern hydroclimate hinge-line. This research focuses on understanding the common era (CE; last 2000 years) hydroclimate variability and its driving mechanisms using lake sediment archives from two hydrologically restricted Iowan kettle lakes, West Lake Okoboji (~1800 years long) and Clear Lake (~2000 years long). The results of multiproxy sedimentological, geochemical, and isotopic analyses reveal a wetter period during the Medieval Climate Anomaly (MCA; 950-1250 CE) and a drier phase during the Little Ice Age (LIA; 1350-1850 CE), aligning with regional patterns in the upper Midwest. Comparisons with regional paleoclimate records suggest that pluvial conditions during the MCA were linked to mean state atmospheric circulation conditions resembling the negative phase of the Pacific-North American (-PNA) teleconnection pattern when Pacific Ocean-atmosphere conditions similarly resembled the negative phase of the Pacific Decadal Oscillation (-PDO). Conversely, drier conditions during the LIA occurred when +PNA-like atmospheric circulation patterns predominated under +PDO-like conditions in the North Pacific Ocean. Comparison with records near the modern hydroclimate hinge-line indicates in-phase relationships with records east of 96˚ W and anti-phased relationships with records west of 96˚ W. This supports idea of the stable hinge line position during the Common Era.

Description
Indiana University-Purdue University Indianapolis (IUPUI)
item.page.description.tableofcontents
item.page.relation.haspart
Cite As
ISSN
Publisher
Series/Report
Sponsorship
Major
Extent
Identifier
Relation
Journal
Source
Alternative Title
Type
Thesis
Number
Volume
Conference Dates
Conference Host
Conference Location
Conference Name
Conference Panel
Conference Secretariat Location
Version
Full Text Available at
This item is under embargo {{howLong}}