@article {2786,
	title = {Younger-Dryas cooling and sea-ice feedbacks were prominent features of the Pleistocene-Holocene transition in Arctic Alaska},
	journal = {Quaternary Science Reviews},
	volume = {169},
	year = {2017},
	month = {Jan-08-2017},
	pages = {330 - 343},
	abstract = {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 (δ18Owc) (Salix spp.) that have been radiocarbon-dated (14C) to produce a multi-millennial record of climatic change on Alaska{\textquoteright}s North Slope during the Pleistocene-Holocene transition (13,500{\textendash}7500 calibrated 14C years before present; 13.5{\textendash}7.5 ka). We first analyzed the spatial and temporal patterns of δ18Owc in living willows growing at upland sites and found that over the last 30 years δ18Owc values in individual growth rings correlate with local summer temperature and inter-annual variations in summer sea-ice extent. Deglacial δ18Owc values from 145 samples of subfossil willows clearly record the Aller{\o}d warm period (\~{}13.2 ka), the Younger Dryas cold period (12.9{\textendash}11.7 ka), and the Holocene Thermal Maximum (11.7{\textendash}9.0 ka). The magnitudes of isotopic changes over these rapid climate oscillations were \~{}4.5{\textperthousand}, which is about 60\% of the differences in δ18Owc 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 δ18Owc 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.},
	keywords = {alaska, Arctic, Bering Strait, Climate change, dendrochronology, north pacific, oxygen isotopes, Paleoclimate, Sea ice, Younger Dryas},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2017.05.012},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0277379117301713},
	author = {Gaglioti, Benjamin V. and Mann, Daniel H. and Wooller, Matthew J. and Jones, Benjamin M. and Wiles, Gregory C. and Groves, Pamela and Kunz, Michael L. and Baughman, Carson A. and Reanier, Richard E.}
}
@article { ISI:000342993200010,
	title = {Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES},
	volume = {119},
	number = {{8}},
	year = {2014},
	month = {AUG},
	pages = {1630-1651},
	type = {Article},
	abstract = {Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (C-14) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9-11.7ka). In contrast, age-offsets were higher (3.0-5.0ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7-9.0ka) and BOlling-AllerOd periods (14.5-12.9ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were similar to 10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.},
	keywords = {carbon cycling, lake sediment, paleoclimatology, permafrost, radiocarbon, Younger Dryas},
	issn = {2169-8953},
	doi = {10.1002/2014JG002688},
	author = {Gaglioti, Benjamin V. and Mann, Daniel H. and Jones, Benjamin M. and Pohlman, John W. and Kunz, Michael L. and Wooller, Matthew J.}
}
@article {169,
	title = {The detailed palaeoecology of a mid-Wisconsinan interstadial (ca. 32 000 (14)C a BP) vegetation surface from interior Alaska},
	journal = {Journal of Quaternary Science},
	volume = {26},
	year = {2011},
	note = {id: 2131; PT: J; TC: 1; UT: WOS:000296091300010},
	pages = {746-756},
	abstract = {We present a multi-proxy reconstruction from a well-preserved vegetation surface (ca. 32 000 (14)C a BP) from the Fox Permafrost tunnel near Fairbanks, Alaska. A thick litter layer of plant material on the vegetation surface is consistent with the vegetation lacking evidence of disturbance. Plant macrofossils and graminoid cuticle analysis show the presence of a graminoid assemblage consistent with phytolith data. The pollen data indicate that trees were not local to the site and that Artemisia sp. was present in the region. The insect and bryophyte reconstructions are consistent with the vascular plant reconstruction, indicating the site was at least periodically wet. delta(13)C values from the graminoids present show a large range encompassing both the wet and dry range displayed by modern graminoids in Alaska. Sequential delta(13)C analyses conducted along the length of leaves attached to the vegetation surface indicate a seasonal shift towards relatively higher water use efficiency. The lower water use efficiency earlier in the growing season may have stemmed from the use of winter season meltwater by plants at the site - a scenario consistent with the site{\textquoteright}s cryostratigraphy. Our multi-proxy reconstruction contributes to the limited palaeoecological data available for graminoid-dominated vegetation present in Eastern Beringia and particularly the interior of Alaska during the mid-Wisconsinan interstadial. Copyright (C) 2011 John Wiley \& Sons, Ltd.},
	issn = {0267-8179},
	doi = {10.1002/jqs.1497},
	author = {Wooller, Matthew J. and Zazula, Grant D. and Blinnikov, Misha and Gaglioti, Benjamin V. and Bigelow, Nancy H. and Sanborn, Paul and Kuzmina, Svetlana and La Farge, Catherine}
}
@article {213,
	title = {Late Pleistocene paleoecology of arctic ground squirrel (Urocitellus parryii) caches and nests from Interior Alaska{\textquoteright}s mammoth steppe ecosystem, USA},
	journal = {Quaternary Research},
	volume = {76},
	year = {2011},
	note = {id: 2130; PT: J; TC: 0; UT: WOS:000296672100009},
	pages = {373-382},
	abstract = {Botanical analyses of fossil and modern arctic ground squirrel (Urocitellus parryii) caches and nests have been used to reconstruct the past vegetation from some parts of Beringia, but such archives are understudied in Alaska. Five modern and four fossil samples from arctic ground squirrel caches and nests provide information on late Pleistocene vegetation in Eastern Beringia. Modern arctic ground squirrel caches from Alaska{\textquoteright}s arctic tundra were dominated by willow and grass leaves and grass seeds and bearberries, which were widespread in the local vegetation as confirmed by vegetation surveys. Late Pleistocene caches from Interior Alaska were primarily composed of steppe and dry tundra graminoid and herb seeds. Graminoid cuticle analysis of fossil leaves identified Calamagrostis canadensis, Koeleria sp. and Carex albonigra as being common in the fossil samples. Stable carbon isotopes analysis of these graminoid specimens indicated that plants using the C(3) photosynthetic pathways were present and functioning with medium to high water-use efficiency. Fossil plant taxa and environments from ground squirrel caches in Alaska are similar to other macrofossil assemblages from the Yukon Territory, which supports the existence of a widespread mammoth steppe ecosystem type in Eastern Beringia that persisted throughout much of the late Pleistocene. (C) Published by Elsevier Inc. on behalf of University of Washington.},
	issn = {0033-5894},
	doi = {10.1016/j.yqres.2011.08.004},
	author = {Gaglioti, Benjamin V. and Barnes, Brian M. and Zazula, Grant D. and Beaudoin, Alwynne B. and Wooller, Matthew J.}
}
