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Lookup NU author(s): Professor Andrew HendersonORCiD
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
The Holocene hydroclimate of south-central Alaska has been studied extensively, but conflicting interpretations between oxygen isotope paleoclimate datasets are seemingly as common as converging reconstructions, in part due to the challenges of interpreting oxygen isotope ratios in terms of climate. Here, we present a new Holocene record of biogenic silica abundance (BSi), diatom flora, and diatom oxygen isotopes (δ18OBSi) analyzed in sediments from Sunken Island Lake (SIL) in the Kenai Peninsula lowlands, which we interpret in the context of previously published paleoclimate records, and use to understand regional changes in hydroclimate. Changes in lake level documented by aerial photography coupled with a survey of regional lake water isotopes indicate SIL is sensitive to changes in the balance of precipitation and evaporation (P-E). However, an analysis of SIL δ18OBSi over the instrumental period indicates that δ18OBSi is sensitive to both P-E and the isotope composition of precipitation (δ18Oprecip), which is driven by changes in the Aleutian Low atmospheric pressure cell (AL). We attribute a ~2‰ increase in δ18OBSi from 5.5 – 4.5 ka to a stronger AL, which resulted in the delivery of isotopically heavier precipitation to the Kenai lowlands, and wetter conditions during the late Holocene. These interpretations are supported by late Holocene increases in the relative abundance of planktonic diatoms and BSi-inferred storminess, and by evidence for higher-than-present lake levels on the paleo-shorelines above SIL at ~1.5 – 0.5 ka. Our dataset demonstrates that this region was characterized by relatively low lake levels and dry climate in the early Holocene, a strengthening of the AL in the late Holocene, and wetter climate during the late Holocene until recent decades.
Author(s): Broadman E, Kaufman DS, Henderson ACG, Berg EE, Anderson RS, Leng MJ, Stahnke SA, Munoz SE
Publication type: Article
Publication status: Published
Journal: Quaternary Science Reviews
Print publication date: 01/08/2020
Online publication date: 06/07/2020
Acceptance date: 08/06/2020
Date deposited: 10/07/2020
ISSN (print): 0277-3791
ISSN (electronic): 1873-457X
Publisher: Elsevier Ltd
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