@article {2689,
	title = {Local glaciers record delayed peak Holocene warmth in south Greenland},
	journal = {Quaternary Science Reviews},
	volume = {241},
	year = {2020},
	month = {Jan-08-2020},
	pages = {106421},
	abstract = {Local glaciers and ice caps (GICs) respond sensitively and quickly, on the scale of decades to centuries, to climate variations. Continuous records of past fluctuations in GIC size provide information on the timing and magnitude of Holocene climate shifts, and a longer-term perspective on 21st century glacier retreat. Although there is broad-scale agreement on millennial-scale trends in Holocene climate variability and fluctuations in local GICs in Greenland, regional variations are only loosely constrained. Here we present three Holocene proglacial lake sediment records from South Greenland, an area with abundant local glaciers but few Holocene-length paleoclimate records. In addition, we use geospatial analysis to model past equilibrium-line altitudes (ELAs) and thereby constrain the magnitude of ablation-season temperature change during the warmest and coolest periods of the Holocene. Physical and geochemical sedimentary characteristics show that two of the proglacial lakes continued to receive glacial meltwater input until \~{}7.3 and \~{}7.1 ka BP. The survival of local glaciers implies that South Greenland remained relatively cool, and that summer temperatures gradually warmed, but did not warm well beyond 1.2 {\textdegree}C above present in the early Holocene. In the mid-Holocene, from \~{}7.1 to 5.5 ka BP, organic sedimentation at these two sites indicates that local glaciers became very small, or more likely melted away completely. The glaciers within the third lake{\textquoteright}s catchment melted away prior to \~{}5.2 ka BP, as sediments deposited earlier in the Holocene could not be dated at this site. We estimate that summer temperatures increased by at least 1.2{\textendash}1.8 {\textdegree}C above present by \~{}7.3{\textendash}7.1 ka BP. Our results are consistent with other observations that suggest a north-to-south gradient in the timing of Holocene thermal maximum conditions, with southern Greenland experiencing a delayed warming relative to other regions in Greenland. As summer temperatures cooled in the Neoglacial, our records show that sustained glacier regrowth began \~{}3.1 ka BP with glaciers in the southernmost catchment, which at present, receive the most precipitation. In the other two catchments, which host smaller glaciers in a drier environment, regrowth began at \~{}1.3 and \~{}1.2 ka BP, the timing of which is in agreement with other glacial records from the Arctic Atlantic region. Local glaciers reached their maximum late Holocene extents during a cooler, second phase of the Little Ice Age (LIA) \~{}0.2-0.1 ka BP, that we estimate was at least 0.4{\textendash}0.9 {\textdegree}C cooler than present. Overall, these findings improve understanding of the spatio-temporal dynamics of Holocene glacier and climate change in Greenland, potentially yielding valuable information about their future response.},
	keywords = {Equilibrium-line altitudes, Greenland, Holocene thermal maximum, lake sediments, Little ice age, Mountain glaciers, Paleotemperatures},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2020.106421},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379120303838},
	author = {Larocca, Laura J. and Axford, Yarrow and Bj{\o}rk, Anders A. and Lasher, G. Everett and Brooks, Jeremy P.}
}
@article {2708,
	title = {Multiple independent records of local glacier variability on Nuussuaq, West Greenland, during the Holocene},
	journal = {Quaternary Science Reviews},
	volume = {215},
	year = {2019},
	month = {Jan-07-2019},
	pages = {253 - 271},
	abstract = {The sensitivity of mountain glaciers to small-scale climate fluctuations makes records of their past extent among the best proxies for identifying spatio-temporal climate variability. Here we build on the few existing Holocene records of local glacier change in Greenland by using three independent geochronological methods{\textemdash}proglacial lake sediment analysis, cosmogenic 10Be surface-exposure dating, and in situ 14C burial modeling{\textemdash}to reconstruct continuous records of Holocene glacier variability on Nuussuaq, West Greenland. 10Be ages of perched boulders indicate eastern Nuussuaq was deglaciated between \~{}11.0 and 10.5 ka. Radiocarbon-dated sediments from two lakes on Nuussuaq contain mineral-rich layers between \~{}9.6 and 9.0 and \~{}8.7{\textendash}8.0 cal ka BP that may be correlative with nearby ice sheet moraines deposited in the early Holocene. Multiple proxies for glacier size indicate frequent, high-amplitude glacier fluctuations superimposed on net glacier growth during the late Holocene, with significant ice expansion phases at \~{}3.7 ka, 2.8 ka, and throughout the past \~{}2 ka. Mean 10Be ages from five nested moraine crests confirm that local glacier extents on Nuussuaq culminated during both the Little Ice Age [\~{}1470 C.E. (n = 3) and 1750 C.E. (n = 3)] and the preceding centuries (\~{}520{\textendash}1320 C.E.; n = 11). Results reveal that local glaciers on Nuussuaq episodically advanced and retreated at centennial timescales throughout the Holocene, most likely in response to regional climate changes in West Greenland superimposed on the progressive insolation-driven cooling trend in the Northern Hemisphere. Our new 10Be moraine chronologies coupled with other glacier-size proxies corroborate an emerging pattern of significant summer cooling and glacier expansion in the centuries prior to the Little Ice Age in the Arctic.},
	keywords = {Cosmogenic 10Be, Cosmogenic in situ 14C, Greenland, Holocene, lake sediment, Mountain glaciers, Neoglaciation},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2019.05.007},
	url = {https://www.sciencedirect.com/science/article/pii/S0277379118308771},
	author = {Schweinsberg, Avriel D. and Briner, Jason P. and Licciardi, Joseph M. and Bennike, Ole and Lifton, Nathaniel A. and Graham, Brandon L. and Young, Nicol{\'a}s E. and Schaefer, Joerg M. and Zimmerman, Susan H.}
}
