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Coupled impacts of sea ice variability and North Pacific atmospheric circulation on Holocene hydroclimate in Arctic Alaska

Lookup NU author(s): Dr Andrew Henderson

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This is the authors' accepted manuscript of an article that has been published in its final definitive form by National Academy of Sciences, 2020.

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Abstract

Arctic Alaska lies at a climatological crossroads between the Arctic and North Pacific Oceans. The modern hydroclimate of the region is responding to rapidly diminishing sea ice, driven in part by changes in heat flux from the North Pacific. Paleoclimate reconstructions have improved our knowledge of Alaska’s hydroclimate, but no studies have examined Holocene sea ice, moisture, and ocean-atmosphere circulation in Arctic Alaska, limiting our understanding of the relationship between these phenomena in the past. Here we present a sedimentary diatom assemblage and diatom isotope dataset from Schrader Pond, located ~80 km from the Arctic Ocean, which we interpret alongside synthesized regional records of Holocene hydroclimate and sea ice reduction scenarios modeled by HadCM3. The paleo data synthesis and model simulations suggest the early and middle Holocene in Arctic Alaska were characterized by less sea ice, a greater contribution of isotopically-heavy Arctic-derived moisture, and wetter climate. In the late Holocene, sea ice expanded and regional climate became drier. This climatic transition is coincident with a documented shift in North Pacific circulation involving the Aleutian Low at ~4 ka, suggesting a Holocene teleconnection between the North Pacific and Arctic. The HadCM3 simulations reveal that reduced sea ice leads to a strengthened Aleutian Low shifted west, potentially increasing transport of warm North Pacific water to the Arctic through the Bering Strait. Our findings demonstrate the interconnectedness of the Arctic and North Pacific on multi19 millennial timescales, and are consistent with future projections of less sea ice and more precipitation in Arctic Alaska.


Publication metadata

Author(s): Broadman E, Kaufman DS, Henderson ACG, Malmierca-Vallet I, Leng MJ, Lacey JH

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences

Year: 2020

Volume: 117

Issue: 52

Pages: 33034-33042

Print publication date: 29/12/2020

Online publication date: 07/12/2020

Acceptance date: 12/11/2020

Date deposited: 19/11/2020

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences

URL: https://doi.org/10.1073/pnas.2016544117

DOI: 10.1073/pnas.2016544117


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