Younger-Dryas cooling and sea-ice feedbacks were prominent features of the Pleistocene-Holocene transition in Arctic Alaska

QUATERNARY SCIENCE REVIEWS

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Article

Gaglioti, Benjamin V.¹  Mann, Daniel H.²  Wooller, Matthew J.³  Jones, Benjamin M.⁴  Wiles, Gregory C.⁵  Groves, Pamela⁶  Kunz, Michael L.⁷  Baughman, Carson A.⁴  Reanier, Richard E.⁸ 

[1] Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9w, Palisades, NY 10964 USA

[2] Univ Alaska Fairbanks, Dept Geosci, 900 Yukon Dr, Fairbanks, AK 99775 USA

[3] Univ Alaska Fairbanks, Coll Fisheries & Ocean Sci, Water & Environm Res Ctr, 306 Tanana Dr, Fairbanks, AK 99775 USA

[4] US Geol Survey, Alaska Sci Ctr, 4210 Univ Dr, Anchorage, AK 99508 USA

[5] Coll Wooster, Dept Geol, 1189 Beall Ave, Wooster, OH 44691 USA

[6] Univ Alaska Fairbanks, Inst Arctic Biol, 902 North Koyukuk Dr, Fairbanks, AK 99775 USA

[7] Univ Alaska Fairbanks, Sch Nat Resources & Extens, POB 757140, Fairbanks, AK 99775 USA

[8] Reanier Assoc Inc, 1215 SW 170th St, Seattle, WA 98166 USA

关键词: Arctic Alaska;    Paleoclimate;    Oxygen isotopes;    Climate change;    Sea ice;    Dendrochronology;    Younger Dryas;    North Pacific;    Bering Strait;   

DOI  :  10.1016/j.quascirev.2017.05.012

来源: Elsevier

【 摘 要 】

Declining sea-ice extent is currently amplifying climate warming in the Arctic. Instrumental records at high latitudes are too short-term to provide sufficient historical context for these trends, so paleoclimate archives are needed to better understand the functioning of the sea ice-albedo feedback. Here we use the oxygen isotope values of wood cellulose in living and sub-fossil willow shrubs (delta O-18(wc)) (Salix spp.) that have been radiocarbon-dated (C-14) to produce a multi-millennial record of climatic change on Alaska's North Slope during the Pleistocene-Holocene transition (13,500-7500 calibrated 14C years before present; 13.5-7.5 ka). We first analyzed the spatial and temporal patterns of delta O-18(wc) in living willows growing at upland sites and found that over the last 30 years delta O-18(wc) values in individual growth rings correlate with local summer temperature and inter-annual variations in summer sea-ice extent. Deglacial delta O-18(wc) values from 145 samples of subfossil willows clearly record the Allerod warm period (similar to 13.2 ka), the Younger Dryas cold period (12.9-11.7 ka), and the Holocene Thermal Maximum (11.7-9.0 ka). The magnitudes of isotopic changes over these rapid climate oscillations were similar to 4.5 parts per thousand, which is about 60% of the differences in delta O-18(wc) between those willows growing during the last glacial period and today. Modeling of isotope-precipitation relationships based on Rayleigh distillation processes suggests that during the Younger Dryas these large shifts in 6180,c values were caused by interactions between local temperature and changes in evaporative moisture sources, the latter controlled by sea ice extent in the Arctic Ocean and Bering Sea. Based on these results and on the effects that sea-ice have on climate today, we infer that ocean-derived feedbacks amplified temperature changes and enhanced precipitation in coastal regions of Arctic Alaska during warm times in the past. Today, isotope values in willows on the North Slope of Alaska are similar to those growing during the warmest times of the Pleistocene-Holocene transition, which were times of widespread permafrost thaw and striking ecological changes. (C) 2017 Elsevier Ltd. All rights reserved.

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